Actually, quite a lot. For those with a keen interest in the Potsdam sandstone of Eastern Ontario, Quebec and Northern New York State, the following articles, abstracts and field trip guides are worth a look. They are arranged from the most recent dating back to 2010.
The first article is instructive, as it explains how to recognize the differences between braided fluvial strata and ephemeral fluvial strata that are found in the Potsdam Group Sandstones, but you will want to read it numerous times. (I did.) Interestingly, the abstract for the first article mentions: “Two fluvial facies associations, braided and ephemeral fluvial, are recognized in strata of the Cambrian–Ordovician Potsdam Group in the Ottawa Embayment and Quebec Basin in northeastern North America. ... [I]n the upper part of the Potsdam two regional ephemeral fluvial units are interstratified with two braided fluvial units, providing evidence for shifts in regional climate. ... These changes are correlated with documented Late Cambrian to Earliest Ordovician global climate fluctuations, with semiarid conditions and related ephemeral fluvial systems corresponding to global cooling events at ca. 491 and 487 Ma.”
What I found most useful in Lowe and Arnott’s (2016a) article are the figures and the summary of the Potsdam Group which “is now recognized as a group comprising three formations that range in age from uppermost Lower Cambrian to Lower Ordovician. The oldest is the Altona Formation, which consists of arkose, siltstone, mudstone, and dolostone and records a marine transgression during the Early to Middle Cambrian in the Quebec Basin . The marine Altona Formation is overlain by the Middle Cambrian Ausable Formation, made up of braided fluvial arkose and conglomerate that are thickest in the eastern Ottawa Embayment and Quebec Basin, and overlain by redbed eolian quartz arenites present mainly in the southwestern part of the Ottawa Embayment. An unconformity, in places angular, separates the Ausable Formation from the overlying Upper Cambrian–Lower Ordovician Keeseville Formation The Keeseville Formation consists of quartz arenites and minor conglomerate of fluvial, eolian, marginal marine, and shallow marine origin. The contact between the Potsdam Group and overlying Theresa Formation is defined by a change from marine siliciclastic to mixed siliciclastic–carbonate strata associated with the epeiric Sauk transgression. Age and contact relationships indicate that this contact is locally an erosional discontinuity but elsewhere conformable, ” [citations omitted]. That summary should be compared with their Figure 3, a regional correlation of cross-sections from three locations showing interstratified ephemeral units, braided fluvial units and the marginal to fully marine units, and with the cross-sections in Lowe, Arnott, and Sanford (2013) and in Lowe (2014).
Lowe (2014) reports that “new biostratigraphic analyses from this study (Nowlan, 2013) indicate that an interval stratigraphically below the uppermost Potsdam Group (the Riviere Aux Outardes Mb of the Covey Hill Fm) is Lowermost Ordovician (Early Tremadocian) (Figure 3). We therefore consider the uppermost Potsdam in the western Ottawa Embayment to be of Lower Ordovician age”. Lowe (2014) also notes that “Existing and new ages of the basal Theresa Formation indicate that the switch from pure siliciclastic (Potsdam) to mixed siliciclastic-carbonate (Theresa) was diachronous, younging from the southwest to the northeast”.
In Ontario, from about 1982, we had been dividing the Potsdam Group into (a) a lower Covey Hill formation (feldspathic sandstone and conglomerate); and (b) an upper Nepean Formation (fluvial gravels and sandstone; eolian sandstone; and shallow marine facies sandstone). Sanford and Arnott (2010) added numerous refinements, including noting the presence of a regional uncomformity within the Potsdam Group separating the underlying Covey Hill (Ontario and Quebec)/Ausable (New York) from the overlying Nepean (Ontario)/Keeseville (New York)/Cairnside (Quebec), and subdividing the Covey Hill into four units – the Jericho/Altona, overlain by the Hannawa Falls, Chippewa Bay and Edwardsville members.
David Lowe (2014) uses allostratigraphy (correlation of unconformity-bound units) to subdivide and correlate the Potsdam Group and has proposed lithostratigraphic revisions. He proposes (starting at the oldest, and using mostly his words):
Allomember 1: Altona Formation: uppermost Early Cambrian to Middle Cambrian: only recognized in the Quebec basin... It consists of wave/stormdominated marine shoreface/shelf deposits.
Allomember 2: Ausable Formation (proposed revision): Middle to lower Upper Cambrian:
consists of fluvial arkose that reach a thickness of ~600 m along the axis of the Oka-Beauharnois Arch and is exposed as outliers elsewhere (the Covey Hill Member, proposed) and of red bed aeolian quartz arenites (Hannawa Falls Member, proposed),
Allomember 3: Chippewa Bay and Riviere Aux Outardes Members of the Keeseville Formation
(proposed revision): Upper Cambrian to Lowermost Ordovician: consists of widespread but thin quartz arenites and quartz cobble-boulder conglomerates of fluvial origin (Chippewa Bay Member, proposed) overlain in the northern Ottawa Embayment by marine sandstones with local mudstone and carbonate interbeds (Riviere Aux Outardes Member, proposed). The fluvial Chippewa Bay member of allomember 3 makes up the thickest part of the Potsdam [in upper NY State], and consists of braided perennial and ephemeral depositional facies associations.
Allomember 4: Nepean Member of Keeseville Formation (proposed): Lower Ordovician: consists of basal terrestrial and overlying marginal marine and tide-dominated shallow marine quartz arenite that forms the uppermost Potsdam. Allomember 4 is locally conformably but abruptly overlain or unconformably overlain by the mixed carbonate and siliciclastic Theresa Formation. [T]he switch from pure siliciclastic (Potsdam) to mixed siliciclastic-carbonate (Theresa) was diachronous, younging from the southwest to the northeast.
Jaret (2015) reports on U-Pb ages of zircons from the Potsdam at Alexandria Bay, NY, which yielded concordant ages of two populations: 1100 Ma and 2500 Ma. Only the first can be Grenville sourced. Allaz, Selleck, Williams and Jercinovic (2013) dated monazite from the Potsdam Formation, New York and reported that “Monazite core ages yield Proterozoic ages between 1.17 and 0.90 Ga (Shawinigan and Ottawan orogeny). Monazite overgrowth and xenotime ages indicate four to five major overgrowth events between ca. 500 Ma (shortly after the time of deposition) and ca. 200 Ma.”
Christopher Brett
Perth, Ontario
++++++++++++++++++++++++++++++++++++++++++++++++++++++++
David G. Lowe, R.W.C. Arnott, 2016a
Composition and Architecture of Braided and Sheetflood-Dominated Ephemeral Fluvial Strata In the Cambrian–Ordovician Potsdam Group: A Case Example of the Morphodynamics of Early Phanerozoic Fluvial Systems and Climate Change
Journal of Sedimentary Research, v. 86, i. 6, p. 587-612, Published in June 2016, doi:10.2110/jsr.2016.39
David G. Lowe and Bill Arnott, 2016b
Paleotopographic Controls on Fluvial Architecture of Pre-Vegetated Braided Fluvial Strata in a Basal Cambrian-Ordovician Sandstone: Potsdam Group of the Ottawa Embayment and Quebec Basin; Abstract with program, Article #90259, AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 22, 2016
www.searchanddiscovery.com/abstracts/html/2016/90259ace/abstracts/2382851.html
Tadeusz Bartek Splawinski, J Patterson, M Kwiatkowski, 2016
The late Cambrian interface of sea and land: paleoecology and paleoenvironment of the Upper Cairnside Formation, Potsdam Group, near Beauharnois, Quebec, Canada. Northeastern Geoscience, Volume 34, pages 13 – 22
https://www.researchgate.net/publication/304952493_
David G. Lowe and Bill Arnott, 2015a
Supercritical strata in Lower Paleozoic fluvial rocks: a super critical link to upper flow regime processes and preservation in nature. EGU General Assembly 2015, held 12-17 April, 2015 in Vienna, Austria. id.7279
meetingorganizer.copernicus.org/EGU2015/EGU2015-7279.pdf
David G. Lowe and Bill Arnott, 2015b
Supercritical strata in Lower Paleozoic fluvial rocks: a super critical link to upper flow regime processes and preservation in nature. Dirt Talk, Department of Earth Sciences, Dalhousie University, April 10, 2015
http://www.dal.ca/faculty/science/earth-sciences/news-events/events/2015/04/10/dirt_talk___david_lowe.html
David Lowe, Charlotte Mehrtens and Ryan Brink, 2015
Sedimentology and Stratigraphy of the Cambrian Potsdam Group (Altona, Ausable and. Keeseville Formations), Northeastern New York. Field Trip, New York State Geological Association, 87th Annual Meeting, State University of New York at Plattsburgh, Plattsburgh, NY, 12–13 September 2015
Ryan A Brink, 2015
Sedimentologic Comparison Of The Late/lower Early Middle Cambrian Altona Formation And The Lower Cambrian Monkton Formation; M.Sc. Thesis, University of Vermont, 134 p.
http://scholarworks.uvm.edu/graddis/370
http://scholarworks.uvm.edu/cgi/viewcontent.cgi?article=1369&context=graddis
Mángano, M.G. and Buatois, L.A., 2015,
The trace-fossil record of tidal flats through the Phanerozoic: Evolutionary innovations and faunal turnover, in McIlroy, D., ed., ICHNOLOGY: Papers from ICHNIA III: Geological Association of Canada, Miscellaneous Publication 9, p. 157-177 at 159-161, Figure 7 and 171.
Steven Jaret, 2015
Provenance of the Potsdam Sandstone from laser ablation U-Pb ages of detrital Zircons. Geological Society of America Abstracts with Programs. Vol. 47, No. 3, p.80
https://gsa.confex.com/gsa/2015NE/webprogram/Paper252725.html
MacNaughton, R.B., Hagadorn, J.W., Lacelle, M., and Groulx, P., 2014
The perils of Protichnites: The checkered history of an iconic ichnotaxon.
Alberta Palæontological Society, Paleo 2014, Annual Symposium, Abstracts and Short Papers, Mount Royal University, Calgary, Alberta, p. 34. http://www.academia.edu/8412586/The_perils_of_Protichnites_the_checkered_history_of_an_iconic_ichnogenus_ABSTRACT_
MacNaughton, R.B., and Hagadorn, J.W., 2014
The perils of Protichnites: Revisiting the earliest-named arthropod trackways.
GAC-MAC Joint Annual Meeting, Fredericton, 2014, Abstracts, Volume 37, page 170
http://www.mineralogicalassociation.ca/doc/AbstractVolume2014Final.pdf
David G. Lowe and Bill Arnott, 2014a
Variations in Braided Fluvial Styles Related to Topography and Climate in the Cambrian-Ordovician Potsdam Group, Ottawa Embayment and Quebec Basin
AAPG Annual Convention and Exhibition, Houston, TX, April 8, 2014
http://www.searchanddiscovery.com/pdfz/documents/2014/51004lowe/ndx_lowe.pdf.html
http://www.searchanddiscovery.com/abstracts/html/2014/90189ace/abstracts/1840976.html
David G. Lowe and Bill Arnott, 2014b
Coeval Tectonism and Epeiric Transgression on the Early Paleozoic Laurentian Platform Recorded by Strata of the Potsdam Group in the Northwestern Ottawa Embayment
AAPG Annual Convention and Exhibition, Houston, TX, April 7, 2014
http://www.searchanddiscovery.com/abstracts/html/2014/90189ace/abstracts/1840946.html
David G. Lowe, 2014
Stratigraphy and Terrestrial to Shallow Marine Environments the Potsdam Group in the Southwestern Ottawa Embayment ; New York State Geological Association 86th Annual Meeting, Field Trip B-4, 183
https://www.researchgate.net/publication/280924108_
Sören Jensen, Luis A. Buatois and M. Gabriela Mángano , 2013,
Testing for palaeogeographical patterns in the distribution of Cambrian trace fossils, Chapter 5 in Early Palaeozoic Biogeography and Palaeogeography, Geological Society, London, Memoirs 2013, volume 38, p. 45-58
doi: 10.1144/M38.5
Seamus Magnus, Dave Lowe, Jamie Cutts, and Travis McCarron, 2013,
OCGC Field Trip – September 27th to 29th 2013
earthsci.carleton.ca/sites/default/files/Field%20Guide%202013.pdf
Julien Allaz, Bruce Selleck, Michael L. Williams, Michael J. Jercinovic 2013
Microprobe analysis and dating of monazite from the Potsdam Formation, New York: A progressive record of chemical reaction and fluid interaction. American Mineralogist, 98 (7) 1106-1119 http://dx.doi.org/10.2138/am.2013.4304
Lowe, David G., Arnott, R.W.C., Chiarenzelli, Jeffrey R., and Sanford, B.V., 2013
Cratonic arch activity and basin dissection in early Paleozoic southeast Laurentia recorded by pre- and syn-transgressive strata of the Potsdam Group. The Geological Society of America, 125th Annual Meeting, Abstracts with Programs, Vol. 45, No. 7, p. 475, Paper 195-1
https://gsa.confex.com/gsa/2013AM/webprogram/Paper232272.html
David G. Lowe, Robert W. C. Arnott, and Bruce V. Sanford, 2013,
Before the Great North American Carbonate Bank: A Complex Cambrian-Lower Ordovician Transgressive History Recorded in Siliciclastic Strata of the Potsdam Group, Southeast Laurentia
Adapted from extended abstract prepared in conjunction with oral presentation at AAPG Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19 -22, 2013
http://www.searchanddiscovery.com/pdfz/documents/2013/50859lowe/ndx_lowe.pdf.html
Mario Lacelle, James W. Hagadorn and Pierre Groulx, 2012
Prolific Potsdam Protichnites: Giant euhycarcinoid trackways from Beauharnois, Québec
Canadian Paleontology Conference, University of Toronto 2012, Proceedings No. 10: 43.
www.mpe-fossiles.org/resources/Lacelle_etal_2012.pdf
James W. Hagadorn, Mario Lacelle, and Pierre Groulx, 2012
Mirabel's ancient surfers: Insights from Cambrian trace fossils and sedimentology of the Potsdam Group, Québec; Canadian Paleontology Conference, University of Toronto 2012, Abstract Volume, page 37
http://www.mpe-fossiles.org/resources/Hagadorn_etal_2012.pdf
D. Lowe and R.W.C. Arnott, 2012
The Potsdam Group in New York State, Ontario and Quebec: stratigraphic relationships and character of continental and shallow marine sedimentation in a tectonically active continental basin. GAC-MAC Joint Annual Meeting, Volume 35, pages 80-81
James W. Hagadorn, Joseph H. Collette, and Edward S. Belt, 2011
Eolian-aquatic deposits and faunas of the Middle Cambrian Potsdam Group
Palaios 26(5):314-334 May 2011
DOI: 10.2307/25835633
Anonymous, 2010
[Attributed to Selleck, B., Arnott, R.W.C. and Sanford, B. V.] Potsdam Formation Field Excursion, July 22-25, 2010, Thousand Island Region and St. Lawrence Lowlands. Colgate University.
www.colgate.edu/.../Field%20trip%20Information%20July%2022%202010.pdf
Bruce V. Sanford and Robert W.C. Arnott, 2010
Stratigraphic and structural framework of the Potsdam Group in eastern Ontario, western Quebec, and northern New York State. Geological Survey of Canada, Bulletin 597, 85 pages
publications.gc.ca/collections/collection_2010 /nrcan/M42-597
Friday, 5 August 2016
Tuesday, 5 July 2016
Mark your calendars for a Guided Quarry Tour on September 10, 2016
One of Lanark County’s claims to fame is the high quality maple syrup that is produced at the maple sugar bushes that are located throughout Lanark County. Each year Perth celebrates with a Festival of the Maples held the last Saturday in April. (This year was the 40th annual Festival of the Maples.) I’d swear that half the county attends. At this year’s Maple Fest I noted that one of the booths selling maple syrup was operated by Tom Lalonde & Family Farm and manned by Tom and his wife. Those with an interest in geology in Lanark County will know that Tom is a geologist who is the Quarry Manager at OMYA’s Tatlock marble quarry. My wife and I stopped to buy some maple syrup and maple butter and while there I told Tom that both my wife and I had really enjoyed the tour of OMYA’s marble quarry last fall. I was pleasantly surprised to learn that OMYA will be hosting another tour this year on Saturday, September 10th. Mark your calendars for an enjoyable tour.
Last year OMYA provided buses (thankfully, not school buses) to transport visitors around and down into the quarry. In addition it provided a refreshment tent with cold drinks, burgers and hotdogs available. The refreshment tent also served to provide a history of the quarry told through posters mounted on the inside walls of the tent.
OMYA is a world leader in the production of calcium carbonate which it mines from quarries located throughout the world. In Lanark County it operates a quarry at Tatlock which is said to be the largest calcium carbonate mine in Canada and to produce the purest calcium carbonate in the world. OMYA mines and crushes the calcium carbonate at the Tatlock quarry and processes the product at its plant west of Perth along Highway 7. OMYA’s calcium carbonate products have many applications including being used in paints, plastics, construction materials, paper and packaging materials.
The Tatlock quarry is about 900 meters long, 400 meters wide and 110 meters deep. It is located about 30 km north of Perth up Highway 511, turning right on McIlraith Road. There is more than ample parking available in the fields opposite the quarry entrance. A Google satellite view of the quarry can be obtained by typing 45.145370, -76.497971 into the Google search engine and searching under MAPS, and switching to SatelliteView, or by going to:
http://wikimapia.org/95877/Tatlock-Quarry-OMYA
Last year the guided bus tour of the Tatlock quarry was advertised for Saturday September 12th, 2015 from 10am til 2pm, rain or shine. I expect the tour will operate over similar hours this year. Below are two photographs that I took last year while on the tour. In the first photo, at the bottom of the quarry, is a bus for scale.
Christopher Brett
Perth, Ontario
++++++++++++++++
Update: On August 22, 2016 I phoned OMYA in Perth and confirmed that the quarry tour is still scheduled for September 10th. I was told that advertisements for the tour will appear in the local papers over the next two weeks.
Last year OMYA provided buses (thankfully, not school buses) to transport visitors around and down into the quarry. In addition it provided a refreshment tent with cold drinks, burgers and hotdogs available. The refreshment tent also served to provide a history of the quarry told through posters mounted on the inside walls of the tent.
OMYA is a world leader in the production of calcium carbonate which it mines from quarries located throughout the world. In Lanark County it operates a quarry at Tatlock which is said to be the largest calcium carbonate mine in Canada and to produce the purest calcium carbonate in the world. OMYA mines and crushes the calcium carbonate at the Tatlock quarry and processes the product at its plant west of Perth along Highway 7. OMYA’s calcium carbonate products have many applications including being used in paints, plastics, construction materials, paper and packaging materials.
The Tatlock quarry is about 900 meters long, 400 meters wide and 110 meters deep. It is located about 30 km north of Perth up Highway 511, turning right on McIlraith Road. There is more than ample parking available in the fields opposite the quarry entrance. A Google satellite view of the quarry can be obtained by typing 45.145370, -76.497971 into the Google search engine and searching under MAPS, and switching to SatelliteView, or by going to:
http://wikimapia.org/95877/Tatlock-Quarry-OMYA
Last year the guided bus tour of the Tatlock quarry was advertised for Saturday September 12th, 2015 from 10am til 2pm, rain or shine. I expect the tour will operate over similar hours this year. Below are two photographs that I took last year while on the tour. In the first photo, at the bottom of the quarry, is a bus for scale.
Christopher Brett
Perth, Ontario
++++++++++++++++
Update: On August 22, 2016 I phoned OMYA in Perth and confirmed that the quarry tour is still scheduled for September 10th. I was told that advertisements for the tour will appear in the local papers over the next two weeks.
Sunday, 26 June 2016
Perthite from Near Perth, Ontario; Part 3
I’ve previously written about Perthite from Perth, Ontario. In my posting from Monday, January 14, 2013 I mention two outcrops south of Perth where it is believed that Dr. James Wilson found the original specimens, that Dr. Thomas Thomson at the University of Glasgow performed the initial chemical analysis and named Perthite, that T. Sterry Hunt of the Geological Survey of Canada subsequently published a better description of the Perthite and better chemical analysis to correct Dr. Thomson’s "unfortunate want of precision in his mineralogical description" and problems with Dr. Thomson’s reported chemical composition.
I also provided a link to The Hunterian Museum and Art Gallery, University of Glasgow, which has a photograph on its web site of what is likely the original specimen of Perthite sent by Dr. Wilson to Dr. Thomson (Hunterian catalogue number M2361 ). See:
http://www.huntsearch.gla.ac.uk/cgi-bin/foxweb/huntsearch/LargeImage.fwx?collection=all&catno=M2361&mdaCode=GLAHM&filename=M2361a.jpg#caption
In my posting from Wednesday, June 12, 2013 I mentioned a visit by Luis Sánchez-Muñoz and Professor Martin to Perth, discussed Sánchez-Muñoz’s 2012 paper entitled The Evolution of Twin Patterns in Perthitic K-Feldspar from Granitic Pegmatites, and referred to an article by Charles H Warren entitled A Quantitative Study of Certain Perthitic Feldspars, that was published in 1915, which provided a description and analysis of Perthite from the type locality near Perth which Warren estimated contained 51.9% Microcline by weight and 47.3% Albite by weight.
There has been a recent article published on Perthite from the type locality near Perth, Ontario by two Scottish professors: Martin R. Lee of the School of Geographical and Earth Sciences, University of Glasgow, and Ian Parsons of the Grant Institute of Earth Science, University of Edinburgh. The citation for the article follows:
Martin R. Lee, Ian Parsons (2015)
Diffusion-controlled and replacement microtextures in alkali feldspars from two pegmatites: Perth, Ontario and Keystone, South Dakota,
Mineralogical Magazine, December 2015, 79 (7) 1711-1735
DOI: 10.1180/minmag.2015.079.7.21,
http://minmag.geoscienceworld.org/content/79/7/1711
Published online on February 09, 2016
Lee and Parsons compared perthitic microcline from Perth, Ontario (Wards catalogue 46 E 0510) and perthitic microcline from Keystone, South Dakota (Wards 46 E 5125) with the sample of the type perthite from Perth, Ontario (Hunterian Museum, Glasgow, M2361). The two Wards samples were studied using light and electron microscopy while the type perthite from the Hunterian Museum was compared using light microscopy.
Lee and Parsons report that the type specimen differs in bulk composition and microtexture from the Wards sample from Perth (and from the Keystone sample) and conclude that although the Wards sample from Perth and type specimen likely come from the same general locality, the Wards sample described in their paper is not the type material.
Interestingly, they did not analyze the bulk composition of the type specimen or the Wards sample from Perth. They noted that Hunt's two analyses (1851) correspond with a bulk composition of Or41.2Ab55.5An3.4, which they use for the composition of the type specimen M2361. For the bulk composition of the Wards sample from Perth they rely on an analysis conducted by Holdren and Speyer, 1987 which yielded a bulk composition of Or57.4Ab42.0An0.6. They note that the type is more albitic than the Wards’ sample. They don’t mention Warren’s 1915 analysis of Perthite from the type locality (mentioned above), which appears to be in the middle of their two bulk compositions.
Lee and Parsons make some interesting observations on the type specimen: “In thin section ... M2361 is a vein perthite with albite forming periodically distributed lenticular sheets, overall parallel to b , but locally slightly oblique. At low power, lamellae appear relatively smooth-sided, although in detail the interfaces are serrated. ... The average periodicity of the lenses is ~0.5 mm. The albite has a pronounced {110} cleavage , and in places a second feldspar, presumably microcline, forms thin{110} plates partially outlining albite subgrains . In some regions the lenses adopt a more nearly equidimensional, globular shape, and there are also regions in which thick albite lamellae are missing. Fine-scale, film microperthite occurs in these regions. Most of the microcline has very regular, straight-sided tartan twinning, with occasional regions of coarser twinning. It forms a matrix to the albite films, and is crowded with tiny euhedral plates of orange-brown biotite, most abundant in the central parts of the microcline lamellae. This suggests that the formation of biotite was related to the replacement process that produced the macroperthite. The plates of biotite have no visible effect, at the LM scale, on the tartan twinning. The biotite presumably accounts for the dark brown colour of the microcline in this sample and also the golden schiller noted by Hunt and visible in our fragment. The albite has fine-scale Albite twinning, varying in thickness, and sometimes showing lateral off-sets suggesting deformation or the presence of subgrains.”
[References to their figures omitted]
I find it interesting that the golden schiller noted by Hunt (1851) was noted by Lee and Parsons in the thin section of the type specimen M2361 in the Hunterian Museum, Glasgow and attributed to plates of biotite. Charles Warren (1915) for perthite from the type locality near Perth, attributed the red color of the dark reddish-brown microcline “to the presence of exceedingly minute crystal scales of hematite which are chiefly contained to the microcline. They are usually arranged along definite crystallographic directions.”
I’ve collected a number of specimens of Perthite from the outcrop on the west side of Elm Grove Road looking for – but not finding – a golden schiller in any specimens. While it is possible that the Wards specimens of Perthite from Perth also come from this outcrop (I’ve been told by a friend who was born and raised in Lanark County not far from the outcrop that a tremendous volume of Perthite was collected from the outcrop on Elm Grove Road when the road was widened), Lee and Parsons' comment on the Wards specimen that it is "less obviously perthitic" than the type specimen does not accord with the outcrop.
The outcrop on Elm Grove Road is one of the two outcrops of pegmatite containing perthite that are found approximately 8.5 kilometers (five miles) south of the Town of Perth, in the third lot of Concession VI, North Burgess Township, Lanark County. The second outcrop is about 200 metres to the north of the outcrop on Elm Grove Road, on the northeast side of Glenn Drive. I do have one specimen from that location. In my specimen of perthite from the Glenn Drive outcrop the microcline does have a dark brown colour, darker than the microcline from Elm Grove Road, but I attributed it to the fact that the specimen is more weathered and not as fresh as the samples from Elm Grove Road. It would be interesting to have my specimen of Perthite from Glenn Drive analyzed to see if it matches Hunt’s composition. Perhaps Glenn Drive is the type location rather than off Elm Grove Road?
Christopher Brett
Perth, Ontario
I also provided a link to The Hunterian Museum and Art Gallery, University of Glasgow, which has a photograph on its web site of what is likely the original specimen of Perthite sent by Dr. Wilson to Dr. Thomson (Hunterian catalogue number M2361 ). See:
http://www.huntsearch.gla.ac.uk/cgi-bin/foxweb/huntsearch/LargeImage.fwx?collection=all&catno=M2361&mdaCode=GLAHM&filename=M2361a.jpg#caption
In my posting from Wednesday, June 12, 2013 I mentioned a visit by Luis Sánchez-Muñoz and Professor Martin to Perth, discussed Sánchez-Muñoz’s 2012 paper entitled The Evolution of Twin Patterns in Perthitic K-Feldspar from Granitic Pegmatites, and referred to an article by Charles H Warren entitled A Quantitative Study of Certain Perthitic Feldspars, that was published in 1915, which provided a description and analysis of Perthite from the type locality near Perth which Warren estimated contained 51.9% Microcline by weight and 47.3% Albite by weight.
There has been a recent article published on Perthite from the type locality near Perth, Ontario by two Scottish professors: Martin R. Lee of the School of Geographical and Earth Sciences, University of Glasgow, and Ian Parsons of the Grant Institute of Earth Science, University of Edinburgh. The citation for the article follows:
Martin R. Lee, Ian Parsons (2015)
Diffusion-controlled and replacement microtextures in alkali feldspars from two pegmatites: Perth, Ontario and Keystone, South Dakota,
Mineralogical Magazine, December 2015, 79 (7) 1711-1735
DOI: 10.1180/minmag.2015.079.7.21,
http://minmag.geoscienceworld.org/content/79/7/1711
Published online on February 09, 2016
Lee and Parsons compared perthitic microcline from Perth, Ontario (Wards catalogue 46 E 0510) and perthitic microcline from Keystone, South Dakota (Wards 46 E 5125) with the sample of the type perthite from Perth, Ontario (Hunterian Museum, Glasgow, M2361). The two Wards samples were studied using light and electron microscopy while the type perthite from the Hunterian Museum was compared using light microscopy.
Lee and Parsons report that the type specimen differs in bulk composition and microtexture from the Wards sample from Perth (and from the Keystone sample) and conclude that although the Wards sample from Perth and type specimen likely come from the same general locality, the Wards sample described in their paper is not the type material.
Interestingly, they did not analyze the bulk composition of the type specimen or the Wards sample from Perth. They noted that Hunt's two analyses (1851) correspond with a bulk composition of Or41.2Ab55.5An3.4, which they use for the composition of the type specimen M2361. For the bulk composition of the Wards sample from Perth they rely on an analysis conducted by Holdren and Speyer, 1987 which yielded a bulk composition of Or57.4Ab42.0An0.6. They note that the type is more albitic than the Wards’ sample. They don’t mention Warren’s 1915 analysis of Perthite from the type locality (mentioned above), which appears to be in the middle of their two bulk compositions.
Lee and Parsons make some interesting observations on the type specimen: “In thin section ... M2361 is a vein perthite with albite forming periodically distributed lenticular sheets, overall parallel to b , but locally slightly oblique. At low power, lamellae appear relatively smooth-sided, although in detail the interfaces are serrated. ... The average periodicity of the lenses is ~0.5 mm. The albite has a pronounced {110} cleavage , and in places a second feldspar, presumably microcline, forms thin{110} plates partially outlining albite subgrains . In some regions the lenses adopt a more nearly equidimensional, globular shape, and there are also regions in which thick albite lamellae are missing. Fine-scale, film microperthite occurs in these regions. Most of the microcline has very regular, straight-sided tartan twinning, with occasional regions of coarser twinning. It forms a matrix to the albite films, and is crowded with tiny euhedral plates of orange-brown biotite, most abundant in the central parts of the microcline lamellae. This suggests that the formation of biotite was related to the replacement process that produced the macroperthite. The plates of biotite have no visible effect, at the LM scale, on the tartan twinning. The biotite presumably accounts for the dark brown colour of the microcline in this sample and also the golden schiller noted by Hunt and visible in our fragment. The albite has fine-scale Albite twinning, varying in thickness, and sometimes showing lateral off-sets suggesting deformation or the presence of subgrains.”
[References to their figures omitted]
I find it interesting that the golden schiller noted by Hunt (1851) was noted by Lee and Parsons in the thin section of the type specimen M2361 in the Hunterian Museum, Glasgow and attributed to plates of biotite. Charles Warren (1915) for perthite from the type locality near Perth, attributed the red color of the dark reddish-brown microcline “to the presence of exceedingly minute crystal scales of hematite which are chiefly contained to the microcline. They are usually arranged along definite crystallographic directions.”
I’ve collected a number of specimens of Perthite from the outcrop on the west side of Elm Grove Road looking for – but not finding – a golden schiller in any specimens. While it is possible that the Wards specimens of Perthite from Perth also come from this outcrop (I’ve been told by a friend who was born and raised in Lanark County not far from the outcrop that a tremendous volume of Perthite was collected from the outcrop on Elm Grove Road when the road was widened), Lee and Parsons' comment on the Wards specimen that it is "less obviously perthitic" than the type specimen does not accord with the outcrop.
The outcrop on Elm Grove Road is one of the two outcrops of pegmatite containing perthite that are found approximately 8.5 kilometers (five miles) south of the Town of Perth, in the third lot of Concession VI, North Burgess Township, Lanark County. The second outcrop is about 200 metres to the north of the outcrop on Elm Grove Road, on the northeast side of Glenn Drive. I do have one specimen from that location. In my specimen of perthite from the Glenn Drive outcrop the microcline does have a dark brown colour, darker than the microcline from Elm Grove Road, but I attributed it to the fact that the specimen is more weathered and not as fresh as the samples from Elm Grove Road. It would be interesting to have my specimen of Perthite from Glenn Drive analyzed to see if it matches Hunt’s composition. Perhaps Glenn Drive is the type location rather than off Elm Grove Road?
Christopher Brett
Perth, Ontario
Friday, 29 April 2016
A specimen of Eozoon Canadense at the Matheson House Museum in Perth, Ontario
Eozoön (ē-o-zō’on) a supposed gigantic fossil foraminifer found in marble of the Laurentian
rocks of Canada , whence the name Eozoön Canadense; so called from the Greek ēōs,
dawn, and zōon, an animal, as being the oldest life traceable in the past history of
the globe. Now generally regarded of mineral origin (Charles Morris, 1917)
Below is a photograph of a slabbed and polished specimen of Eozoon Canadense that is in a display cabinet on the third floor of the Matheson House Museum in Perth, Ontario. The specimen is said to be from North Burgess Township, Lanark County, Ontario. The specimen is about 7 inches (17 cm) wide. Eozoon Canadense, shown in the middle to upper half of the specimen, consists of the thin 1 mm thick alternating bands of green serpentine (with grains of spinel) and bands of grey dolomite.
The banding appears as raised ridges on one weathered edge of the specimen that is in the display cabinet. I suspect that most people, if they stumbled across a rock containing Eozoon would identify it as marble containing green serpentine, and might collect it for a rock garden.
What most who look at the specimen will not realize is that this rock has quite the history, and the one page commentary at the museum that describes the specimen and briefly sets out the controversy surrounding whether Eozoon is of organic origin or is inorganic and results from metamorphism, does not and cannot convey the magnitude of the controversy that surrounds Eozoon Canadense. Hundreds of scholarly articles in scientific journals (most published in the period from 1863 to 1899), numerous letters to the editor and four books have been devoted to Eozoon. It is hard to believe the controversy that Eozoon caused. Not just the leading geologists, paleontologists and mineralogists were involved. Leading biologists from England and Germany entered the fray. Besides the obstinance of the opposing parties, and their distinct lack of tact when attacking and dissecting opposing views and when questioning the qualifications of those asserting opposite views, there are various reasons for the controversy. The most important factor that led to the controversy is that Eozoon is found in Precambrian rocks that before the finding of Eozoon had been considered azoic – devoid of life.
A further factor that fueled the controversy is that Eozoon is found only in crystalline limestone showing varying degrees of metamorphism. Did metamorphism create the structure or modify an existing structure?
In addition there are five main types of Eozoon Canadense (all from the Precambrian rocks of the Grenville province of the Canadian Shield):
- the Burgess type, alternating bands of dark green serpentine with grains of spinel and thinner bands of grey dolomite, from North Burgess, south of Perth, Ontario
- the Calumet type, alternating bands of a light grey clinopyroxene and bands of calcite, from Grand Calumet along the Ottawa River
- the Côte St. Pierre type, alternating layers of white calcite and light green serpentine, from near Grenville, Quebec
- the Tudor type, parallel crescentic bands of calcite, from Tudor township in Hastings County, Ontario about 45 miles inland from the shore of Lake Ontario, in comparatively unaltered crystalline limestone
- the Huntingdon type, quartz bands alternating with bands of tremolite and calcite, from the Henderson Talc mine a few miles southeast of Madoc, in Huntingdon Township, Hastings County, Ontario
Further, not everyone that commented believed that the Tudor type and the Huntingdon type should even be classified as Eozoon. In addition, not everyone looked at all of the five main types of specimens, and few of the commentators looks at the specimens in the field. Most relied on thin sections and hand specimens provided by others.
The story started innocently enough. A few years before 1858 Dr. James Wilson, a physician and amateur geologist in Perth collected specimens from North Burgess township (just south of Perth) that he sent to his friend William E. Logan, Provincial Geologist for the Geological Survey of Canada. In 1858 somewhat similar banded specimens were collected by John McMullen of the Geological Survey from the Grand Calumet, an island along the Ottawa River, upstream from Ottawa. Logan thought the specimens strongly resembled fossils and displayed them at scientific meetings in the USA in 1859 and in England in 1862 as evidence of organic structures in Precambrian rocks, but met with little acceptance.
Logan (1863) in the Geology of Canada speculated that the Grand Calumet specimens “present parallel or apparently concentric layers, resembling the Stomatopora rugosa”, a common fossil, recognized the similar appearance between the specimens from North Burgess and Grand Calumet, and the differences in mineral composition between the specimens, and commented that “If both are to be regarded as the results of unaided mineral arrangements, it would seem strange that identical forms should be derived from such different compositions.” Below is the drawing of the “Supposed fossil from the Laurentian limestone, Grand Calumet” that appeared in Logan’s (1863) the Geology of Canada:
Below is a drawing of a specimen of Eozoon collected by Dr. Wilson of Perth, that appeared in Dawson’s 1875 book Life’s Dawn on Earth: Being the History of the Oldest Known Fossil Remains, And Their Relations to Geological Time and to the Development of the Animal Kingdom.
In 1863 members of the Geological Survey of Canada found further specimens of Eozoon at Grenville, Quebec and nearby at Côte St. Pierre. Logan tried to get Elkanah Billings involved, but he declined, and the microscopic slides of the specimens were passed to J. William Dawson at McGill to study. Dawson arrived at the conclusion that they were “of animal nature”, a foraminifer which he named Eozoon Canadense, the dawn animal of Canada. Dawson and Logan enlisted the aid of Professor William Carpenter, an English naturalist and expert on marine zoology, notably in the lower organisms–foraminifera and crinoids. Carpenter agreed with Logan and Dawson. In 1865 each of Logan, Dawson and Carpenter, with a contribution from Sterry Hunt, published papers in the Journal of the Geological Society of London stating that Eozoon Canadense were giant fossil foraminifer.
The controversy started when William King and Thomas Rowney, mineralogy and chemistry professors at Queen’s College, Galway, Ireland, published on June 10, 1865 a letter to the editor of the London Reader, a weekly journal, asserting that Eozoon was “nothing more than the effect of crystallization and segregation.” Carpenter responded in the next issue of the London Reader questioning the qualifications and competence of both King and Rowney. King responded by letter published in the London Reader with a personal attack on Carpenter. So began a series of letters to the editor and articles in scientific journals by Logan, Dawson and Carpenter on one side and King and Rowney (and numerous others) on the other, each side attacking and dissecting opposing views (and the qualifications of those asserting opposite views).
In 1866 King and Rowney published an article in the Journal of the Geological Society of London setting out their investigations and why they believed Eozoon was of mineralogical origin.
In 1867 both Logan and Dawson reported on new specimens of Eozoon from (a) Tudor township in Hastings County, Ontario, that had been found in fairly unaltered crystalline limestone without serpentine, and (b) from southeast of Madoc. I suspect that Logan and Dawson expected that these new specimens would answer King and Rowney’s objections, but they merely added fuel to an acrimonious debate.
Notable articles opposing an organic origin were written by H. J. Carter, a marine zoologist, Otto Hahn and Karl Möbius, two German zoologists, and J. W. Gregory, a geologist with the British museum. Logan and Dawson did receive support (for example, Darwin, G.F. Matthews, Bigsby and Rupert Jones expressed support for their views), but there were many more people opposed to their views than supported them.
The debate raged until 1894 when specimens that were clearly formed by the metamorphism of limestone were found as blocks ejected from Mount Somma near Mount Vesuvius in Italy. These specimens were said to be identical to Eozoon. Limestone altered by magma and ejected from a volcano is not a fossil, and most geologists were convinced that the structure of Eozoon was therefore not a fossil. This did not deter Dawson, who, until he died, kept asserting Eozoon was of organic origin, denying that the specimens from Somma resembled in composition, mode of occurrence, or form and structure, the Eozoon of Canada.
The above is but a summary of the controversy. Charles F. O’Brien (1970) provides an entertaining eighteen page summary of the controversy, while Hofmann (1971) provides a seven page summary of the controversy, plus three plates showing specimens. Both are worth reading. O’Brien concentrates on the arguments made by the various parties, while Hofmann concentrates on the differences between the type specimens. O’Brien concluded that “Little doubt remains of the inorganic origin of Eozoon”, mentioning that “The active Eozoonist cause died with Dawson”. Hofmann concludes that Eozoon is inorganic, mentioning that the problem of the origin of the Burgess and Huntingdon types lies within the realms of metamorphic petrology and mineralogy, that for the Côte St. Pierre type, a “convincing case for an origin by contact metamorphism” was made, that the Grand Calumet type “appears to be a fracture-filling phenomenon” as does the Tudor type. Hofmann does note that the Huntingdon type has “a certain resemblance to lamellar stromatolites ...[but] this resemblance is only superficial... and the individual mineral bands are considerably thicker than in stromatolites”.
Despite both O’Brien and Hofmann concluding that Eozoon is inorganic, that is not the end of the tale. Fenton and Fenton (1952) provide an eight page summary of the Eozoon controversy and conclude “most mineralogists maintain the conservative view that the supposed fossil is the product of metamorphism; lumps of minerals and nothing more. A growing number of paleontologists conclude that the slightly metamorphosed masses are stromatolites of algal origin. ” In a later book Fenton and Fenton (1958) provide a two page summary of the Eozoon controversy and mention that “Dawson found fossils resembling Eozoon in rocks in Hastings County, Ontario. Not only were these eozoons virtually unmodified by heat, steam, or compression: they were undeniably related to structures that have come to be know as stromatolites... This relationship, however, did not immediately establish the eozoons as fossils.” This was because stromatolites at that time were not considered fossils, but inorganic concretions.
It was left to work in the early 1980's by Marika S. Bourque and other members of the Ontario Geological Survey to recognize and promote the Huntingdon type Eozoon, namely quartz bands alternating with bands of tremolite and calcite, from a few miles southeast of Madoc, and found in surrounding townships, as being of biogenic origin– silicified and recrystallized algal colonies. Bartlett and DeKemp (1987) comment “Eozoon canadense comprises several similar, but distinct morphologies. A biogenic origin for one of these forms, the “huntingdon” type, has recently gained general acceptance, largely due to the contribution of M.S. Bourque to the present study. This does not, however, imply an organic origin for the other Eozoon canadense forms...” R. M. Easton (1992), relying on Bourque and deKemp, commented “Eozoon canadense huntingdon is an algal-laminate stromatolite. Other E. canadense types, however, may not be biosedimentary in origin and should be regarded for the moment as pseudofossils...”
One is left to wonder whether the Tudor type and the other more metamorphosed types are also stromatolites. Fenton and Fenton (1952) comment:
“A few radicals– or are they true conservatives?– suspect that even the most highly metamorphosed masses are also fossils, but have been changed so greatly that their true nature appears only when banks or reefs are examined in the original rock. All factions agree on just one point: Eozoon is not a foraminifer, as Dawson and Carpenter tried to prove."
Christopher Brett
Perth, Ontario
++++++++++++++++++++++++++++++++++++++++++++++++++++
Bartlett, J .R. and DeKemp , E. A., 1987
Lithofacies, Stromatolite Localities, Metallic Mineral Occurrences, and Geochemical Anomalies associated with Carbonate Metasediments of the Burleigh Falls-Bancroft-Madoc Area, Southern Ontario. Ontario Geological Survey, Map. P.3079
Bourque, Marika S., 1981
Stratigraphy and Sedimentation of Carbonate Metasediments Within the Grenville Supergroup, Ontario Geological Survey, Summary of Field Work, 1981 , Miscellaneous Paper 100, 77-79
Bourque, Marika S., 1982
Stratigraphy and Sedimentation of Carbonate Metasediments within the Grenville Supergroup
in the Havelock-Madoc-Bancroft Area, Ontario Geological Survey, Summary of Field Work, 1982, Miscellaneous Paper 106, 89-91
Easton, R. M., 1992
The Grenville Province and Proterozoic History of Central and Southern Ontario, Chapter 19 in Geology of Ontario, Ontario Geological Survey Special Volume 4, Part 1, pages 715-904 at 796-797
Fenton, Carroll Lane and Fenton, Mildred Adams, 1952
Giants of Geology, Doubleday & Company, Inc., Garden City, New York
Fenton, Carroll Lane and Fenton, Mildred Adams, 1958
The Fossil Book: A Record of Prehistoric Life, Doubleday, New York
Hofmann, H. J., 1971
Precambrian Fossils, Pseudofossils and Problematica in Canada,
Geological Survey of Canada, Bulletin 189, 146 pages
Logan, W. E, 1863
Geology of Canada, Geological Survey of Canada, Report of Progress from its Commencement to 1863, Montreal, Dawson Brothers, 983 pages
O’Brien, Charles F., 1970
Eozoon Canadense “The Dawn animal of Canada”, ISIS, A Journal of the History of Science Society, Volume 61, No. 2, 206-223
Dawson, J. William, 1875,
The Dawn of Life: Being the History of the Oldest Known Fossil Remains, And Their Relations to Geological Time and to the Development of the Animal Kingdom
Dawson Brothers, Montreal, 239 pages
This book was also released in 1875 in a second edition of two thousand as:
Life’s Dawn on Earth: Being the History of the Oldest Known Fossil Remains, And Their Relations to Geological Time and to the Development of the Animal Kingdom
Hodder and Stoughton, London, England, 239 pages
https://books.google.ca/books?id=mQrWjgEACAAJ
Dawson, Sir J. William, 1888,
On Specimens of Eozoon Canadense and Their Geological and Other Relations.
Peter Redpath Museum, McGill University, Montreal, 106 pages
King, William and Rowney, Thomas Henry, 1881
An Old Chapter of the Geological Record with a New Interpretation: Or, Rock-metamorphism (especially the Methylosed Kind) and Its Resultant Imitations of Organisms: With an Introduction Giving an Annotated History of the Controversy on the So-called "Eozoon Canadense," and an Appendix
London: John Van Voorst, https://books.google.ca/books?id=ocq7AAAAIAAJ
Preface and introduction: pages i-lvii, plus 142 Pages of text and plates;
Pages ix - lvii summarize King and Rowney’s views of the papers on Eozoon written from 1858 to 1880
Hauer, Max, 1885,
Das Eozoon canadense. Eine micro-geologische Studis, 55 pages with 18 photographic plates. Leipzig, Germany.
rocks of Canada , whence the name Eozoön Canadense; so called from the Greek ēōs,
dawn, and zōon, an animal, as being the oldest life traceable in the past history of
the globe. Now generally regarded of mineral origin (Charles Morris, 1917)
Below is a photograph of a slabbed and polished specimen of Eozoon Canadense that is in a display cabinet on the third floor of the Matheson House Museum in Perth, Ontario. The specimen is said to be from North Burgess Township, Lanark County, Ontario. The specimen is about 7 inches (17 cm) wide. Eozoon Canadense, shown in the middle to upper half of the specimen, consists of the thin 1 mm thick alternating bands of green serpentine (with grains of spinel) and bands of grey dolomite.
The banding appears as raised ridges on one weathered edge of the specimen that is in the display cabinet. I suspect that most people, if they stumbled across a rock containing Eozoon would identify it as marble containing green serpentine, and might collect it for a rock garden.
What most who look at the specimen will not realize is that this rock has quite the history, and the one page commentary at the museum that describes the specimen and briefly sets out the controversy surrounding whether Eozoon is of organic origin or is inorganic and results from metamorphism, does not and cannot convey the magnitude of the controversy that surrounds Eozoon Canadense. Hundreds of scholarly articles in scientific journals (most published in the period from 1863 to 1899), numerous letters to the editor and four books have been devoted to Eozoon. It is hard to believe the controversy that Eozoon caused. Not just the leading geologists, paleontologists and mineralogists were involved. Leading biologists from England and Germany entered the fray. Besides the obstinance of the opposing parties, and their distinct lack of tact when attacking and dissecting opposing views and when questioning the qualifications of those asserting opposite views, there are various reasons for the controversy. The most important factor that led to the controversy is that Eozoon is found in Precambrian rocks that before the finding of Eozoon had been considered azoic – devoid of life.
A further factor that fueled the controversy is that Eozoon is found only in crystalline limestone showing varying degrees of metamorphism. Did metamorphism create the structure or modify an existing structure?
In addition there are five main types of Eozoon Canadense (all from the Precambrian rocks of the Grenville province of the Canadian Shield):
- the Burgess type, alternating bands of dark green serpentine with grains of spinel and thinner bands of grey dolomite, from North Burgess, south of Perth, Ontario
- the Calumet type, alternating bands of a light grey clinopyroxene and bands of calcite, from Grand Calumet along the Ottawa River
- the Côte St. Pierre type, alternating layers of white calcite and light green serpentine, from near Grenville, Quebec
- the Tudor type, parallel crescentic bands of calcite, from Tudor township in Hastings County, Ontario about 45 miles inland from the shore of Lake Ontario, in comparatively unaltered crystalline limestone
- the Huntingdon type, quartz bands alternating with bands of tremolite and calcite, from the Henderson Talc mine a few miles southeast of Madoc, in Huntingdon Township, Hastings County, Ontario
Further, not everyone that commented believed that the Tudor type and the Huntingdon type should even be classified as Eozoon. In addition, not everyone looked at all of the five main types of specimens, and few of the commentators looks at the specimens in the field. Most relied on thin sections and hand specimens provided by others.
The story started innocently enough. A few years before 1858 Dr. James Wilson, a physician and amateur geologist in Perth collected specimens from North Burgess township (just south of Perth) that he sent to his friend William E. Logan, Provincial Geologist for the Geological Survey of Canada. In 1858 somewhat similar banded specimens were collected by John McMullen of the Geological Survey from the Grand Calumet, an island along the Ottawa River, upstream from Ottawa. Logan thought the specimens strongly resembled fossils and displayed them at scientific meetings in the USA in 1859 and in England in 1862 as evidence of organic structures in Precambrian rocks, but met with little acceptance.
Logan (1863) in the Geology of Canada speculated that the Grand Calumet specimens “present parallel or apparently concentric layers, resembling the Stomatopora rugosa”, a common fossil, recognized the similar appearance between the specimens from North Burgess and Grand Calumet, and the differences in mineral composition between the specimens, and commented that “If both are to be regarded as the results of unaided mineral arrangements, it would seem strange that identical forms should be derived from such different compositions.” Below is the drawing of the “Supposed fossil from the Laurentian limestone, Grand Calumet” that appeared in Logan’s (1863) the Geology of Canada:
Below is a drawing of a specimen of Eozoon collected by Dr. Wilson of Perth, that appeared in Dawson’s 1875 book Life’s Dawn on Earth: Being the History of the Oldest Known Fossil Remains, And Their Relations to Geological Time and to the Development of the Animal Kingdom.
In 1863 members of the Geological Survey of Canada found further specimens of Eozoon at Grenville, Quebec and nearby at Côte St. Pierre. Logan tried to get Elkanah Billings involved, but he declined, and the microscopic slides of the specimens were passed to J. William Dawson at McGill to study. Dawson arrived at the conclusion that they were “of animal nature”, a foraminifer which he named Eozoon Canadense, the dawn animal of Canada. Dawson and Logan enlisted the aid of Professor William Carpenter, an English naturalist and expert on marine zoology, notably in the lower organisms–foraminifera and crinoids. Carpenter agreed with Logan and Dawson. In 1865 each of Logan, Dawson and Carpenter, with a contribution from Sterry Hunt, published papers in the Journal of the Geological Society of London stating that Eozoon Canadense were giant fossil foraminifer.
The controversy started when William King and Thomas Rowney, mineralogy and chemistry professors at Queen’s College, Galway, Ireland, published on June 10, 1865 a letter to the editor of the London Reader, a weekly journal, asserting that Eozoon was “nothing more than the effect of crystallization and segregation.” Carpenter responded in the next issue of the London Reader questioning the qualifications and competence of both King and Rowney. King responded by letter published in the London Reader with a personal attack on Carpenter. So began a series of letters to the editor and articles in scientific journals by Logan, Dawson and Carpenter on one side and King and Rowney (and numerous others) on the other, each side attacking and dissecting opposing views (and the qualifications of those asserting opposite views).
In 1866 King and Rowney published an article in the Journal of the Geological Society of London setting out their investigations and why they believed Eozoon was of mineralogical origin.
In 1867 both Logan and Dawson reported on new specimens of Eozoon from (a) Tudor township in Hastings County, Ontario, that had been found in fairly unaltered crystalline limestone without serpentine, and (b) from southeast of Madoc. I suspect that Logan and Dawson expected that these new specimens would answer King and Rowney’s objections, but they merely added fuel to an acrimonious debate.
Notable articles opposing an organic origin were written by H. J. Carter, a marine zoologist, Otto Hahn and Karl Möbius, two German zoologists, and J. W. Gregory, a geologist with the British museum. Logan and Dawson did receive support (for example, Darwin, G.F. Matthews, Bigsby and Rupert Jones expressed support for their views), but there were many more people opposed to their views than supported them.
The debate raged until 1894 when specimens that were clearly formed by the metamorphism of limestone were found as blocks ejected from Mount Somma near Mount Vesuvius in Italy. These specimens were said to be identical to Eozoon. Limestone altered by magma and ejected from a volcano is not a fossil, and most geologists were convinced that the structure of Eozoon was therefore not a fossil. This did not deter Dawson, who, until he died, kept asserting Eozoon was of organic origin, denying that the specimens from Somma resembled in composition, mode of occurrence, or form and structure, the Eozoon of Canada.
The above is but a summary of the controversy. Charles F. O’Brien (1970) provides an entertaining eighteen page summary of the controversy, while Hofmann (1971) provides a seven page summary of the controversy, plus three plates showing specimens. Both are worth reading. O’Brien concentrates on the arguments made by the various parties, while Hofmann concentrates on the differences between the type specimens. O’Brien concluded that “Little doubt remains of the inorganic origin of Eozoon”, mentioning that “The active Eozoonist cause died with Dawson”. Hofmann concludes that Eozoon is inorganic, mentioning that the problem of the origin of the Burgess and Huntingdon types lies within the realms of metamorphic petrology and mineralogy, that for the Côte St. Pierre type, a “convincing case for an origin by contact metamorphism” was made, that the Grand Calumet type “appears to be a fracture-filling phenomenon” as does the Tudor type. Hofmann does note that the Huntingdon type has “a certain resemblance to lamellar stromatolites ...[but] this resemblance is only superficial... and the individual mineral bands are considerably thicker than in stromatolites”.
Despite both O’Brien and Hofmann concluding that Eozoon is inorganic, that is not the end of the tale. Fenton and Fenton (1952) provide an eight page summary of the Eozoon controversy and conclude “most mineralogists maintain the conservative view that the supposed fossil is the product of metamorphism; lumps of minerals and nothing more. A growing number of paleontologists conclude that the slightly metamorphosed masses are stromatolites of algal origin. ” In a later book Fenton and Fenton (1958) provide a two page summary of the Eozoon controversy and mention that “Dawson found fossils resembling Eozoon in rocks in Hastings County, Ontario. Not only were these eozoons virtually unmodified by heat, steam, or compression: they were undeniably related to structures that have come to be know as stromatolites... This relationship, however, did not immediately establish the eozoons as fossils.” This was because stromatolites at that time were not considered fossils, but inorganic concretions.
It was left to work in the early 1980's by Marika S. Bourque and other members of the Ontario Geological Survey to recognize and promote the Huntingdon type Eozoon, namely quartz bands alternating with bands of tremolite and calcite, from a few miles southeast of Madoc, and found in surrounding townships, as being of biogenic origin– silicified and recrystallized algal colonies. Bartlett and DeKemp (1987) comment “Eozoon canadense comprises several similar, but distinct morphologies. A biogenic origin for one of these forms, the “huntingdon” type, has recently gained general acceptance, largely due to the contribution of M.S. Bourque to the present study. This does not, however, imply an organic origin for the other Eozoon canadense forms...” R. M. Easton (1992), relying on Bourque and deKemp, commented “Eozoon canadense huntingdon is an algal-laminate stromatolite. Other E. canadense types, however, may not be biosedimentary in origin and should be regarded for the moment as pseudofossils...”
One is left to wonder whether the Tudor type and the other more metamorphosed types are also stromatolites. Fenton and Fenton (1952) comment:
“A few radicals– or are they true conservatives?– suspect that even the most highly metamorphosed masses are also fossils, but have been changed so greatly that their true nature appears only when banks or reefs are examined in the original rock. All factions agree on just one point: Eozoon is not a foraminifer, as Dawson and Carpenter tried to prove."
Christopher Brett
Perth, Ontario
++++++++++++++++++++++++++++++++++++++++++++++++++++
References
Bartlett, J .R. and DeKemp , E. A., 1987
Lithofacies, Stromatolite Localities, Metallic Mineral Occurrences, and Geochemical Anomalies associated with Carbonate Metasediments of the Burleigh Falls-Bancroft-Madoc Area, Southern Ontario. Ontario Geological Survey, Map. P.3079
Bourque, Marika S., 1981
Stratigraphy and Sedimentation of Carbonate Metasediments Within the Grenville Supergroup, Ontario Geological Survey, Summary of Field Work, 1981 , Miscellaneous Paper 100, 77-79
Bourque, Marika S., 1982
Stratigraphy and Sedimentation of Carbonate Metasediments within the Grenville Supergroup
in the Havelock-Madoc-Bancroft Area, Ontario Geological Survey, Summary of Field Work, 1982, Miscellaneous Paper 106, 89-91
Easton, R. M., 1992
The Grenville Province and Proterozoic History of Central and Southern Ontario, Chapter 19 in Geology of Ontario, Ontario Geological Survey Special Volume 4, Part 1, pages 715-904 at 796-797
Fenton, Carroll Lane and Fenton, Mildred Adams, 1952
Giants of Geology, Doubleday & Company, Inc., Garden City, New York
Fenton, Carroll Lane and Fenton, Mildred Adams, 1958
The Fossil Book: A Record of Prehistoric Life, Doubleday, New York
Hofmann, H. J., 1971
Precambrian Fossils, Pseudofossils and Problematica in Canada,
Geological Survey of Canada, Bulletin 189, 146 pages
Logan, W. E, 1863
Geology of Canada, Geological Survey of Canada, Report of Progress from its Commencement to 1863, Montreal, Dawson Brothers, 983 pages
O’Brien, Charles F., 1970
Eozoon Canadense “The Dawn animal of Canada”, ISIS, A Journal of the History of Science Society, Volume 61, No. 2, 206-223
Books Written on Eozoon
Dawson, J. William, 1875,
The Dawn of Life: Being the History of the Oldest Known Fossil Remains, And Their Relations to Geological Time and to the Development of the Animal Kingdom
Dawson Brothers, Montreal, 239 pages
This book was also released in 1875 in a second edition of two thousand as:
Life’s Dawn on Earth: Being the History of the Oldest Known Fossil Remains, And Their Relations to Geological Time and to the Development of the Animal Kingdom
Hodder and Stoughton, London, England, 239 pages
https://books.google.ca/books?id=mQrWjgEACAAJ
Dawson, Sir J. William, 1888,
On Specimens of Eozoon Canadense and Their Geological and Other Relations.
Peter Redpath Museum, McGill University, Montreal, 106 pages
King, William and Rowney, Thomas Henry, 1881
An Old Chapter of the Geological Record with a New Interpretation: Or, Rock-metamorphism (especially the Methylosed Kind) and Its Resultant Imitations of Organisms: With an Introduction Giving an Annotated History of the Controversy on the So-called "Eozoon Canadense," and an Appendix
London: John Van Voorst, https://books.google.ca/books?id=ocq7AAAAIAAJ
Preface and introduction: pages i-lvii, plus 142 Pages of text and plates;
Pages ix - lvii summarize King and Rowney’s views of the papers on Eozoon written from 1858 to 1880
Hauer, Max, 1885,
Das Eozoon canadense. Eine micro-geologische Studis, 55 pages with 18 photographic plates. Leipzig, Germany.
Thursday, 17 March 2016
When Stromatolites Were called Concretions, Devil’s Pots, Snow-shoe Tracks and Cannon Balls
"The paradox presented by stromatolites is conveyed by Ginburg’s (1991, p. 25) impish comment that “few observers have any difficulty identifying archetypical stromatolites... yet defining stromatolites is controversial”. This is like saying that everyone knows what stromatolites look like, but no one can agree what they are.”
Robert Riding, 2011, The Nature of Stromatolites: 3,500 Years of History and a Century of Research
The premise for this posting is that while most current geologists can put the name stromatolite to a layered structure, either domal or columnar in form, that they realize was formed by sediment trapped and precipitated by algae, those structures were initially identified as concretions (or by a descriptive name) and the identification of the structure as a concretion (or by another name) carried the implication that it was inorganic rather than organic.
Below I mention a number of early papers which identified structures as concretions, and mention a few with interesting names for the structures. I also mention a few early papers that have been overlooked. I deal first with references to structures in Precambrian rocks of the Canadian Shield and then with structures found in Paleozoic rocks in the Ottawa Embayment. The only concretions mentioned that I cannot confirm are stromatolites are the ones reported from near Vermilion Lake.
The stromatolites in the Thunder Bay area of Northern Ontario have been written about extensively. The Gunflint stromatolites (also known as, the Animikie stromatolites) are deservedly well known, as are stromatolites from the nearby Sibley Formation. In addition, the discovery of microbial nanofossils in cherts associated with the Gunflint formation stromatolites advanced our understanding of life in the Precambrian.
Below is a photograph of small (6 cm x 5 cm) slab showing stromatolites from the Gunflint formation. The specimen is comprised of red, white and black chert.
This slab and other specimens were obtained on a collecting trip to Northern Ontario last year by Ed Hinchey and his wife – the proprietors of the Rox Rock Shop on Bedford Street in Westport, Ontario – and are being sold in their shop (along with slabbed specimens displaying stromatolites from Minnesota and Australia). (https://www.facebook.com/ROXRockShop/)
The above specimen was obtained from a locality in an old mining district just south of Kakabeka Falls, which is on the Kaministiquia River, about 20 kilometers west of Thunder Bay.
Ed Hinchey told me that he collected numerous specimens from this locality that he will be cutting into slabs with a rock saw and selling through his shop. By chance, the locality where Ed Hinchey and his wife collected the specimen shown in the above photograph would be within twenty-five kilometers of where W.E. Logan, Alexander Murray and Robert Bell reported structures that are mentioned below.
A leading paper on the Gunflint stromatolites and Sibley stromatolites was written by Dr. Hans J. Hofmann of the Geological Survey of Canada:
Hofmann, H. J., 1969, Stromatolites from the Proterozoic Animikie and Sibley Groups, Ontario,
Geological Survey of Canada, Paper 68-69. 85 pages, including 9 figures and 22 plates.
http://wmsmir.cits.rncan.gc.ca/index.html/pub/geott/ess_pubs/102/102252/pa_68_69.pdf
In that paper Dr. Hofmann mentions (at page 5) that:
“Nearly a century has passed since Robert Bell of the Geological Survey of Canada reported “small coral-like siliceous concretions and vertical cylinders of chalcedony, transverse sections of which shew fine concentric rings resembling agate” from an area just west of Fort William (Bell, 1870, p. 324). He was referring to structures now called stromatolites, in rocks presently identified as part of the Gunflint Formation.”
Authors relying on Hofmann have understood his reference to Bell’s paper as being the first written on the Gunflint stromatolites. However, over two decades earlier W.E. Logan and Alexander Murray of the Geological Survey of Canada had examined the British Shores of Lake Superior and described structures that we now call stromatolites. Mr. Murray’s attention was devoted to the examination of the Kamanitiquia River and Michipicoten River, while Mr. Logan examined the mining claims and the coast generally. Both reported on the structures that we now call the Gunflint stromatolites.
Here is part of Mr. Logan’s report:
“In the vicinity of disturbed parts the chert sometimes passes into chalcedony and agate, and small cracks are filled with what appears to be anthracite. Some of the chert bands appear to be made up of a multitude of minute, irregular, closely aggregated sub-globular bodies, floating as it were in the silicious matrix. Anthracite seems to be present in the centre of some of these, leading to the supposition that the color of the black chert, even where these shapes are not detected, may be owing to the presence of carbon. In some parts of these oolitic chert layers, small blood-red jaspery spots occasionally become interstratified with the black ; ...
Higher in the formation, argillaceous slates become interstratified with argillaceous sandstones in such an altered condition that it is often difficult at first sight to say whether the latter may not be trap layers. The sandstones are sometimes slightly micaceous, and they are rather lighter
in color than the slates or shales; and while the slates sometimes exhibit the structure called cone in cone, the harder bands display spherical concretions varying from a few inches to two and even six feet in diameter. In some parts of the vertical thickness calcareous layers are occasionally interstratified among the slates, but few of them are pure enough to be entitled to the appellation of limestone.”
Logan, W. E., 1847, Geological Survey of Canada, Report of Progress for the Year 1846-47, at pages 13 and 14.
Here is part of Mr. Murray’s report on a calcareous, hard argillaceous slate alternating with beds of chert along the Kamanitiquia River :
“Spheroidal concretions of singular uniformity, and sometimes of large size, are disseminated
through all that part of the formation over which the river passes, and they are more conspicuously displayed among the more shaly portions of the rock. A little above the lowest rapids there is a great accumulation of these concretions, which have been known to the fur-traders for many years under the title of the Devil's Pots. Some of these are six feet in
diameter, with a thickness of two feet, and they are found of all sizes down to that of a pigeon's egg. They are usually more convex on the top than on the bottom, bearing a strong resemblance to the stones used in the game of curling. The lines of lamination are distinctly visible in these
concretions; and in some instances, when not removed from the parent bed, the lines could be traced from the concretion to the partially enclosing rock. They are always highly charged with iron pyrites, and their weight, when they are moderate in size, is in great consequence.”
Alexander Murray, 1847, Report of Andrew Murray, Assistant Provincial Geologist, Addressed to W. E. Logan, Provincial Geologist, in Logan, W. E., 1847, Geological Survey of Canada, Report of Progress for the Year 1846-47, at page 54
Both of those reports were repeated verbatim in Logan, W. E., 1863, Geology of Canada, Geological Survey of Canada, Report of Progress from its Commencement to 1863, 983 pages,
at pages 68 and 69.
Logan’s and Murray’s reports of concretions do not appear to have been widely circulated.
A very brief summary of Murray’s report appeared under the heading “The Kaministiquia to the Height of Land. Mr. Murray on the Valley of the Kaministiquia,” in Papers Relative to the Exploration of the Country between Lake Superior and the Red River Settlement, Presented to Both Houses of Parliament in 1859, where it was mentioned of the slates at the Grand Falls, the rock “shows many of the spheroidal concretions charged with iron pyrites noticed by Mr. Murray in his report.”
Robert Bell of the Geological Survey of Canada appears to have been the next to remark on the Gunflint Stromatolites. In his geological report of the country lying on the north-western side of Lake Superior Robert Bell made three references to the Gunflint Stromatolites:
“The shaly portions hold regularly formed spheroidal concretions of various sizes. ... The shales are seen on the lower part of the Kaminitiquia River, especially at the Grand Falls, and along the coast of Lake Superior, between Fort William and Pigeon River...” [Page 319]
“At about twelve miles south-west of Fort William, and two or three miles north-west of the Shore of Lake Superior, opposite Pie Island, a lake occurs, called Ka-zee-zee-kitchi-wa-ga-mog. ... Sucker Brook, which discharges its waters into the lake, rushes down over underlying almost horizontal shales. These contain numbers of singular spherical concretions, similar those observed by Sir W. E. Logan in the shales of the same formation, in the bed of the Kaminitiquia.” [Page 322]
“three-fourths of a mile north of the town-line of Neebing, nearly horizontal calcareous beds occur, containing small coral-like silicious concretions and vertical cylinders of chalcedony, transverse sections of which shew fine concentric rings resembling agate.” [page 324]
Bell, R. 1870, Report of Mr. Robert Bell, Geological Survey of Canada, Report of Progress from 1866 to 1869, 313-364 at pages 319, 322 and 324. Dated at Montreal, May 23, 1870.
http://archive.org/stream/annualreportgeo15canagoog#page/n10/mode/2up
Interestingly, H.J. Hofmann, who wrote the seminal paper on the Gunflint stromatolites, referred only to Robert Bell and not to Logan and only to Bell’s above third quote mentioning coral-like silicious concretions.
In 1889 Dr. Robert Bell authored a report of a royal commission that was later released as a separate publication, in which he discussed the Animikie strata, mentioning that “Lenticular and spheroidal concretions of various sizes, called also bombs, boulders and kettles, are common throughout the black shales of this division.”
Bell, Robert, 1889, The Geology of Ontario, with Special Reference to Economic Minerals, published at Toronto by Warwick & Sons, 72 pages, a reprint of the Ontario Royal Commission on the Mineral Resources and Measures for their Development.
It is possible that there is an even earlier reference to the Gunflint Formation stromatolites than Logan (1847). Many will be aware that both John Jeremiah Bigsby, M.D., and Commander H. W. Bayfield, Royal Navy, had explored the geology of the Thunder Bay area two decades before Logan, and that each published written reports of their findings. Bayfield reported on outcrops on islands at the east end of “Neepigon Bay” and mentioned greenstone that becomes more or less slaty, sometimes showing signs of stratification, and that it “sometimes contains globular concretions not unlike those observed in the greywacke of the St. Lawrence.” It is hard to tell what he meant by ‘globular concretions’. Interestingly, Hoffman (1969) included a map in his paper on which he plotted the location of Animikie (Gunflint) stromatolites and Sibley Formation stromatolites, and shows Gunflint stromatolites at the east end of Nipigon Bay. Bayfield’s ‘globular concretions’ could be stromatolites.
Bayfield, H. W., 1829, Outlines of the Geology of Lake Superior, Transactions of the Literary and Historical Society of Quebec, Volume 1, pages 1-43 at pages 20-21
John Jeremiah Bigsby, M.D.(1792-1881) – Geologist, Physician, Entomologist, Author and Artist– is no stranger to those with an interest in the geology of Canada. Before Sir William Logan and before Elkanah Billings arrived on the scene, John Jeremiah Bigsby was considered the person most knowledgeable on the subjects of geology and paleontology in the two Canadas. In the years 1820 -1826 he was the medical officer attached to the British party settling the boundary between the United States and British North America, and studied the land surrounding Lake Huron and Lake Superior. While Bigsby reported on the geology at the outlet of the Kaministiquia River into Lake Superior I’ve not been able to find that he reported concretions near Thunder Bay or that he reported on the geology along the Kaministiquia . This may have been because during the summer or 1823 the Americans were instructed to go out from Fort William and up the Kaministiquia River to Lake of the Woods, while the British party (including Bigsby) took the Pigeon River- Grand Portage route from Fort William. (See Epic Wanderer: David Thompson and the Mapping of the Canadian West, By D'Arcy Jenish, 2009, Bison Books, at page 228)
However, Bigsby may have been one of the first to promote what we now call stromatolites as evidence of life in the Precambrian, when he reported on an interesting structure in metamorphic rocks of what we now call the Grenville Province, Canadian Shield. In an article published in 1864 Bigsby reported that he had found on the North shore of the St. Lawrence, at the base of Cape Tourment, 36-40 miles below Quebec City, in close-grained quartzose gneiss, “a circular, cup-like, organic (?) body, two or three inches in diameter, with much the look, as well as the size, of a Maclurea [a large gastropod], not, however, with gyrations, but with concentric rings, one within another; the summits are rounded and not sharp-ridged; no radiating striae nor reticulations were observed in it, but they may exist. It might be very loosely compared to Spongarium interlineatum, or to a Chaetetes ... It is probably organic; and Sir W. Logan intends to examine the locality carefully. Near this fossil (?) And for some hundred yards around, the gneiss....” Unfortunately, I’ve found no further reference to this structure.
Bigsby, J. J., 1864, On the Laurentian Formation, Part II, The Geological Magazine, Volume 1, pages 200 -206 at page 205 http://www.biodiversitylibrary.org/item/97056#page/238/mode/1up
The main thrust of Bigsby’s article on the Laurentian Formation is that because there is evidence of carbon, phosphorus, lime etc. in Precambrian rocks there should be evidence of life, noting for carbon that “This substance is indispensable to organic structure, and is in very great quantity in the Canadas, almost always near to, or imbedded in, marble, which is often at the same time high in phosphate of lime, and contiguous to deposits of magnetic oxide of iron. ... Four of the principal constituents of life are thus brought together in the Laurentian Group; and with every probability that they have been employed as such.” His article has been largely ignored.
In the 1870 field season Mr. James Richardson of the Geological Survey of Canada explored the country north of Lake St. John, Quebec and described the geology from Lake Abatagomaw to Lake Wakinitchie, including near Lake Chibougamau. Today we would call the rocks that Mr. James Richardson examined the Superior Province of the Canadian Shield. Near a bay at the north end of Lake Abatagomaw he mentioned “there are considerable exposures of flattened spheroidal or reniform masses, from a few inches to upwards of a foot in diameter. They are made up of an indurated greenish and purplish argillaceous rock, which is jaspery in its texture. When sections of these spheroids have been exposed to the weather, they present a concentric arrangement of various shades of colour, becoming lighter towards the center.” Past Lake Chibougamau Mr. Richardson reported on “a blackish limestone, about a foot thick, interstratified with serpentine. Dr. Hunt, while examining these rocks, had a portion of the limestone sliced for examination under the microscope, which revealed a structure resembling that of some coral....This Mr. Billings thinks, is a coral, but not determinable generically.”
Richardson, James, 1872, Report on the Country North of Lake St. John, in Geological Survey of Canada, Report of Progress, 1870-1871 at pages 292 and 293
In the 1884 field season A. P. Low of the Geological Survey of Canada examined the rocks near Lake Chibougamau that has been examined by Mr. Richardson and the rocks around Lakes Mistassini and Mistassinis. He reported: “The lower beds resting unconformably on the gneiss, at the western end of Lake Mistassini, are made up of a dark bluish-grey limestone, holding concretionary masses of dark blue chert, with thin bands of black argillaceous shale. Above this are thin beds of light blue fine-grained dolomitic limestone, weathering yellow, interbedded with thin layers of a gritty limestone, containing large quantities of sand. .... Although closely examined, none of the above beds gave any evidence of fossil remains, the supposed fossils found by Mr. Richardson having, on closer examination, proved to be only mineral concretions.”
Low A. P., 1885, Report of the Mistassini expedition, 1884-5, Geological and Natural History Survey of Canada, Annual Report, Volume 1, (1885), Part D, at page 32D
Over a century after Mr. Richardson’s report, H.J. Hofmann commented: “Stromatolites were first reported from the Lake Mistassini area of Central Quebec more than a hundred years ago (Richardson 1872) and most subsequent geological reports make mention of them.... Illustrations accompanying a few of these reports show stratiform, nodular, domal and short columnar types...”
Hofmann H. J., 1978, New stromatolites from the Aphebian Mistassini Group, Quebec; Canadian Journal of Earth Sciences, v. 15, no 4, 571-585, at page 571.
www.nrcresearchpress.com/doi/abs/10.1139/e78-062
keratose sponge, found near Thompson, Minnesota. Some of these masses are two feet in diameter, with rounded outlines, presenting on the weathered or glaciated natural surface a striking contrast with the rock that encloses them. They are locally designated “snow-shoe tracks”.” While true concretions have been reported from the Chelmsford Formation along Highway 144 about 4 kilometers north of Vermilion Lake, I believe that Winchell’s concretions/snow-shoe tracks are stromatolites from the Onwatin Formation or Vermilion Formation, in part because of his comments below.
Winchell, N. H., 1889, Further Observations on the Typical Huronian, and on the Rocks About Sudbury, Ontario, in Report for 1889, Eighteenth Annual Report, Geological and Natural History Society of Minnesota, at page 54
In 1890 field season Dr. Winchell reported his examination of slates near Northern Pacific Junction, Minnesota and reported finding structures similar to those that he had observed at Vermilion Lake near Sudbury. This time he remarked on the prevalence of the “dark calcareous lumps or secretions. These are the same that Drs. Hunt and Dawson supposed to contain traces of a keratose sponge, and which Dr. Selwyn pointed out as “snow-shoe tracks” – so called by the Indians– where their weathered contour- appear on the slates of the Vermilon River. ... When these lumps are fresh they are gray, crystalline apparently consisting essentially of lime, in which, in some parts, the small crystals of calcite are visible in compacted marmorized structure. But there is a layered, concentric, rather coarse structure reminding one of Cryptozoon, across which perpendiculary there is a transverse jointage...”.
Winchell, N. H., 1893, Field Notes of N. H. Winchell, in Report for the year 1891, Twentieth Annual Report, Geological and Natural History Society of Minnesota, at page 29-30.
Harvey, Arthur, 1889, Broad Outlines of the Geology of the Northwest of Lake Superior, Proceedings of the Canadian Institute, Third Series, Volume VI, 218-225 at 235
In November, 1889 Arthur Harvey delivered a paper before The Canadian Institute in which he mentions the Animikie formation’s locally called “cannon-balls”, which he named “Pelotechthen Balanoides– an acorn-shaped thing, grown in or from mud.” He commented “The uniformity of shape proves these things to be a growth; they are sometimes like an orange, often ovoid, and they so often have a slight protuberance on the upper side that I compare them rather to acorn than to an orange or an egg. Their internal structure, too, proves them a growth... [T]here is a very regular layer of pyrites around the nodule... This pyritous ring I have never failed to notice.... I submit that no mere mineral nodule would attain the size of many of these spheroids. I would have thought this growth a protospongia, except for the conditions under which it seems to have lived, that is if it be a zoophyte. .... [T]hey are from the bigness of a hen’s egg to that of a coal scuttle.”
Harvey, Arthur, 1891, Pelotechthen Balanoides, Transactions of the Canadian Institute, Volume 1, pages 213-215
I’ve found no reference where anyone else mentions Pelotechthen Balanoides.
“Immediately beneath the two-feet bed of limestone there is a singular and extensively spread concretionary layer, in some exposures of which, surfaces of half an acre shew the concretions, consisting of concentric layers, cut in half and closely packed together, some of them being two to three feet in diameter.”
Logan, W. E., 1852, Geological Survey of Canada, Report of Progress for the Year 1851-52, at page 19.
Here is part of Mr. Murray’s report:
“At Battle Windmill, a little over a mile below Prescott, the following descending section was measured:--
Pale grey arenaceous impure limestone, weathering bright yellow, and rapidly disintegrating on exposed surface; the bed is filled with concentric concretionary balls, the concentric layers of which are frequently interlined with white calc-spar... 1 ft, 2 inches”
Alexander Murray, 1852, Report of Andrew Murray, Assistant Provincial Geologist, Addressed to W. E. Logan, Provincial Geologist, in Logan, W. E., 1852, Geological Survey of Canada, Report of Progress for the Year 1851-52, pages 58 - 91, at pages 67-68.
Both of those reports were repeated in Logan, W. E., 1863, Geology of Canada, Geological Survey of Canada, Report of Progress from its Commencement to 1863, 983 pages, in his discussion of the Calciferous Formation (in Lanark county, now the March and Oxford) and Chazy Formations. When discussing the Calciferous, Logan mentions (at pages 112-113) that “On this part of the Ottawa [River at Rigaud] the middle portion of the formation is concealed; but the summit is met with on the bank of the river above Carillon, where about a hundred feet of arenaceous limestone and bituminous calcareous clay-stone terminate in a singular and extensively spread concretionary layer, like that noticed in the section below Prescott. In some of the exposures of it on the Grenville canal, about a mile below Grenville village, surfaces of half an acre shew the concretions, consisting of concentric layers seemingly cut horizontally in half and packed closely together, some of them being two to three feet in diameter.”
When discussing the Chazy formation Logan mentions (at page 134) “ Yellowish-grey concretionary limestone, weathering yellowish-brown; the concretionary masses are from six to 18 inches in diameter, and the concentric layers of the concretions thin” and (at page 174) “Black shale supplied in abundance with a coral, of which the specimens have been lost; the upper part holds large concentric concretionary nodules of fine grained black limestone, passing in parts into a bed of black limestone eight inches thick.”
Bernstein (1992) provides the most easily understood analysis of Logan’s Calciferous formation (breaking it into Theresa, a middle Beauharnois, and an upper Carillon), and includes a schematic cross-section, Figure 2, entitled “Generalized lithostratigraphy of the Beekmantown Group in the St. Lawrence Lowlands, Quebec and Ontario” showing the location of domal and columnar stromatolites in the various formations. He also includes a photograph with the caption “Geologist stands on exhumed, large domal stromatolites similar to those described by Logan (1852, 1863) and referred to as Cryptozoon by Grabau (1936).”
Bernstien, L, 1992, A revised lithostratigraphy of the Lower-Middle Ordovician Beekmantown Group, St. Lawrence Lowlands, Quebec and Ontario, Canadian Journal of Earth Sciences 29, 2677-2694 (1992)
Wilson, Morley E., 1924, Arnprior-Quyon and Maniwaki Areas, Ontario and Quebec, Geological Survey of Canada, Memoir 136, 152 pages.
Wilson, Alice E., 1946, Geology of the Ottawa-St. Lawrence Lowland, Ontario and Quebec,
Geological Survey of Canada, Memoir 241, 66 pages.
Both publications provide photographs of what we now call stromatolites. Interestingly, while Dr. Morley Wilson wrote the earlier paper, he was the one more willing to consider the structures as being algal growths. Dr. Alice E. Wilson was in doubt as to whether the structures were concretions or algal growths.
Below is Dr. Morley Wilson’s a photograph of outcrop of Beekmantown dolomite exhibiting Cryptozoon, lot 21, Concession X, Fitzroy Township, Carleton County, Ontario – his plate VIII.
That photograph was taken in 1917 by Dr. Morley Wilson when he conducted field work in the Arnprior-Quyon area. Dr. Morley Wilson commented (at page 45) that “Most of the typical Cryptozoon are a few inches to 18 inches in diameter, but in places somewhat similar, flat, concentrically domed masses are present that attain a diameter of several feet. As seen in horizontal cross-section on the surface of an outcrop the Cryptozoon are circular in form (Plate VIII), but where they are exposed in vertical section they are generally considered flattened and dome-shaped.”
Below is photograph 81893 that Dr. Alice E. Wilson included in Memoir 241 published in 1946.
The caption to the photo, which is Plate II B, is “Oxford dolomite containing crytozoons and showing the characteristic weathering along joint planes.” In the text of the memoir Dr. Alice E. Wilson names the Beekmantown dolomite as the Oxford formation “after Oxford township, Grenville county, Ontario, where it is widely exposed.” She also mentions that “Many of the dolomitic beds contain hard spherical masses, from six inches to 2 feet in diameter, that weather concentrically (Plate II B). They have been considered variously as concretions or as algal growths called ‘cryptozoons’. Natural Resources Canada provides an online searchable database of photographs taken by field officers of the Geological Survey of Canada. In the database Photo Number 81893 has the Caption “Lot 15, Con. viii, Osgoode Twp. Ont. Concretionary Structures In Beekmantown Dolomite”, and mentions that the Photographer is “Wilson, A. E.” and that the photo is dated 1936.
In my November 4, 2015 blog posting I mentioned that in 1924 Dr. Morley E. Wilson of the Geological Survey of Canada had reported that an outcrop of Nepean Sandstone northwest of Ottawa “exhibits concentric ridge forms up to 8 inches in diameter, somewhat similar in appearance to the Cryptozoon structure seen in the Beekmantown dolomite farther to the eastward.” I also mentioned that within the last two decades numerous authors have reported stromatolites in the Potsdam Group sandstone (the upper formation of which is the Nepean).
There were many early reports of concretions in the Potsdam sandstone. Many are associated with the cylindrical structures that are considered to be dewatering structures resulting from springs. The concretions associated with the cylindrical dewatering structures (e.g., those reported at Rossie, New York by Franklin Hough (1853), or those that Dr. Selwyn looked at near Kingston –see Anglin, Boyle and James (1888)) could easily have formed by water circulating from the dewatering structures. However, there are many other early reports of concretions in the Potsdam from Ontario and New York State. For example, Logan (1863) mentions (at page 92) a two foot layer of “Blood-red coarse sandstone with concretionary nodules” near Charleston village. I suspect that some of the early reports of concretions could be stromatolites.
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I found it interesting to look back to see how stromatolites were first identified by early geologists and to see how many different common names were used before the term stromatolite was settled on. I have not mentioned all of the names that my research uncovered, as I’ve restricted this posting to localities in Canada or in the Canadian Shield. I have also not covered the proliferation of scientific names that erupted following Hall naming Cryptozoon in 1883.
Christopher Brett
Perth, Ontario
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1. In 1847 Logan and Murray spelt the river’s name as Kamanitiquia; in 1863, Logan spelt it as Kaministiquia. Bell spelt it Kaminitiquia. It is now spelt Kaministiquia. Murray, Logan and Bell refer to the falls on the Kaministiquia River as the Grand Falls. It is now called the Kakabeka Falls. Bell’s Lake Ka-zee-zee-kitchi-wa-ga-mog is now the pedestrian Loch Lomond. I have not been able to determine the current name for Sucker Brook.
2. Photographs of stromatolites in the Thunder Bay area can be found on the following web pages:
http://www.jon-nelson.com/stromatolites-in-thunder-bay-area#more-344
http://www.mindat.org/sitegallery.php?loc=222478
http://www.mindat.org/sitegallery.php?loc=222731
https://www.geocaching.com/geocache/GC31G74_kakabekia-a-living-fossil
Robert Riding, 2011, The Nature of Stromatolites: 3,500 Years of History and a Century of Research
The premise for this posting is that while most current geologists can put the name stromatolite to a layered structure, either domal or columnar in form, that they realize was formed by sediment trapped and precipitated by algae, those structures were initially identified as concretions (or by a descriptive name) and the identification of the structure as a concretion (or by another name) carried the implication that it was inorganic rather than organic.
Below I mention a number of early papers which identified structures as concretions, and mention a few with interesting names for the structures. I also mention a few early papers that have been overlooked. I deal first with references to structures in Precambrian rocks of the Canadian Shield and then with structures found in Paleozoic rocks in the Ottawa Embayment. The only concretions mentioned that I cannot confirm are stromatolites are the ones reported from near Vermilion Lake.
The Gunflint Stromatolites
The stromatolites in the Thunder Bay area of Northern Ontario have been written about extensively. The Gunflint stromatolites (also known as, the Animikie stromatolites) are deservedly well known, as are stromatolites from the nearby Sibley Formation. In addition, the discovery of microbial nanofossils in cherts associated with the Gunflint formation stromatolites advanced our understanding of life in the Precambrian.
Below is a photograph of small (6 cm x 5 cm) slab showing stromatolites from the Gunflint formation. The specimen is comprised of red, white and black chert.
This slab and other specimens were obtained on a collecting trip to Northern Ontario last year by Ed Hinchey and his wife – the proprietors of the Rox Rock Shop on Bedford Street in Westport, Ontario – and are being sold in their shop (along with slabbed specimens displaying stromatolites from Minnesota and Australia). (https://www.facebook.com/ROXRockShop/)
The above specimen was obtained from a locality in an old mining district just south of Kakabeka Falls, which is on the Kaministiquia River, about 20 kilometers west of Thunder Bay.
Ed Hinchey told me that he collected numerous specimens from this locality that he will be cutting into slabs with a rock saw and selling through his shop. By chance, the locality where Ed Hinchey and his wife collected the specimen shown in the above photograph would be within twenty-five kilometers of where W.E. Logan, Alexander Murray and Robert Bell reported structures that are mentioned below.
Hofmann, 1969, Stromatolites from the Proterozoic Animikie and Sibley Groups
A leading paper on the Gunflint stromatolites and Sibley stromatolites was written by Dr. Hans J. Hofmann of the Geological Survey of Canada:
Hofmann, H. J., 1969, Stromatolites from the Proterozoic Animikie and Sibley Groups, Ontario,
Geological Survey of Canada, Paper 68-69. 85 pages, including 9 figures and 22 plates.
http://wmsmir.cits.rncan.gc.ca/index.html/pub/geott/ess_pubs/102/102252/pa_68_69.pdf
In that paper Dr. Hofmann mentions (at page 5) that:
“Nearly a century has passed since Robert Bell of the Geological Survey of Canada reported “small coral-like siliceous concretions and vertical cylinders of chalcedony, transverse sections of which shew fine concentric rings resembling agate” from an area just west of Fort William (Bell, 1870, p. 324). He was referring to structures now called stromatolites, in rocks presently identified as part of the Gunflint Formation.”
In 1847 Logan and Murray Report Concretions on the Kamanistiquia River and along the Shores of Lake Superior: – an early Report of the Gunflint Stromatolites
Authors relying on Hofmann have understood his reference to Bell’s paper as being the first written on the Gunflint stromatolites. However, over two decades earlier W.E. Logan and Alexander Murray of the Geological Survey of Canada had examined the British Shores of Lake Superior and described structures that we now call stromatolites. Mr. Murray’s attention was devoted to the examination of the Kamanitiquia River and Michipicoten River, while Mr. Logan examined the mining claims and the coast generally. Both reported on the structures that we now call the Gunflint stromatolites.
Here is part of Mr. Logan’s report:
“In the vicinity of disturbed parts the chert sometimes passes into chalcedony and agate, and small cracks are filled with what appears to be anthracite. Some of the chert bands appear to be made up of a multitude of minute, irregular, closely aggregated sub-globular bodies, floating as it were in the silicious matrix. Anthracite seems to be present in the centre of some of these, leading to the supposition that the color of the black chert, even where these shapes are not detected, may be owing to the presence of carbon. In some parts of these oolitic chert layers, small blood-red jaspery spots occasionally become interstratified with the black ; ...
Higher in the formation, argillaceous slates become interstratified with argillaceous sandstones in such an altered condition that it is often difficult at first sight to say whether the latter may not be trap layers. The sandstones are sometimes slightly micaceous, and they are rather lighter
in color than the slates or shales; and while the slates sometimes exhibit the structure called cone in cone, the harder bands display spherical concretions varying from a few inches to two and even six feet in diameter. In some parts of the vertical thickness calcareous layers are occasionally interstratified among the slates, but few of them are pure enough to be entitled to the appellation of limestone.”
Logan, W. E., 1847, Geological Survey of Canada, Report of Progress for the Year 1846-47, at pages 13 and 14.
Here is part of Mr. Murray’s report on a calcareous, hard argillaceous slate alternating with beds of chert along the Kamanitiquia River :
“Spheroidal concretions of singular uniformity, and sometimes of large size, are disseminated
through all that part of the formation over which the river passes, and they are more conspicuously displayed among the more shaly portions of the rock. A little above the lowest rapids there is a great accumulation of these concretions, which have been known to the fur-traders for many years under the title of the Devil's Pots. Some of these are six feet in
diameter, with a thickness of two feet, and they are found of all sizes down to that of a pigeon's egg. They are usually more convex on the top than on the bottom, bearing a strong resemblance to the stones used in the game of curling. The lines of lamination are distinctly visible in these
concretions; and in some instances, when not removed from the parent bed, the lines could be traced from the concretion to the partially enclosing rock. They are always highly charged with iron pyrites, and their weight, when they are moderate in size, is in great consequence.”
Alexander Murray, 1847, Report of Andrew Murray, Assistant Provincial Geologist, Addressed to W. E. Logan, Provincial Geologist, in Logan, W. E., 1847, Geological Survey of Canada, Report of Progress for the Year 1846-47, at page 54
Both of those reports were repeated verbatim in Logan, W. E., 1863, Geology of Canada, Geological Survey of Canada, Report of Progress from its Commencement to 1863, 983 pages,
at pages 68 and 69.
Logan’s and Murray’s reports of concretions do not appear to have been widely circulated.
A very brief summary of Murray’s report appeared under the heading “The Kaministiquia to the Height of Land. Mr. Murray on the Valley of the Kaministiquia,” in Papers Relative to the Exploration of the Country between Lake Superior and the Red River Settlement, Presented to Both Houses of Parliament in 1859, where it was mentioned of the slates at the Grand Falls, the rock “shows many of the spheroidal concretions charged with iron pyrites noticed by Mr. Murray in his report.”
The 1870 Report of Dr. Robert Bell
Robert Bell of the Geological Survey of Canada appears to have been the next to remark on the Gunflint Stromatolites. In his geological report of the country lying on the north-western side of Lake Superior Robert Bell made three references to the Gunflint Stromatolites:
“The shaly portions hold regularly formed spheroidal concretions of various sizes. ... The shales are seen on the lower part of the Kaminitiquia River, especially at the Grand Falls, and along the coast of Lake Superior, between Fort William and Pigeon River...” [Page 319]
“At about twelve miles south-west of Fort William, and two or three miles north-west of the Shore of Lake Superior, opposite Pie Island, a lake occurs, called Ka-zee-zee-kitchi-wa-ga-mog. ... Sucker Brook, which discharges its waters into the lake, rushes down over underlying almost horizontal shales. These contain numbers of singular spherical concretions, similar those observed by Sir W. E. Logan in the shales of the same formation, in the bed of the Kaminitiquia.” [Page 322]
“three-fourths of a mile north of the town-line of Neebing, nearly horizontal calcareous beds occur, containing small coral-like silicious concretions and vertical cylinders of chalcedony, transverse sections of which shew fine concentric rings resembling agate.” [page 324]
Bell, R. 1870, Report of Mr. Robert Bell, Geological Survey of Canada, Report of Progress from 1866 to 1869, 313-364 at pages 319, 322 and 324. Dated at Montreal, May 23, 1870.
http://archive.org/stream/annualreportgeo15canagoog#page/n10/mode/2up
Interestingly, H.J. Hofmann, who wrote the seminal paper on the Gunflint stromatolites, referred only to Robert Bell and not to Logan and only to Bell’s above third quote mentioning coral-like silicious concretions.
The 1889 Report of Dr. Robert Bell - Bombs, Boulders and Kettles
In 1889 Dr. Robert Bell authored a report of a royal commission that was later released as a separate publication, in which he discussed the Animikie strata, mentioning that “Lenticular and spheroidal concretions of various sizes, called also bombs, boulders and kettles, are common throughout the black shales of this division.”
Bell, Robert, 1889, The Geology of Ontario, with Special Reference to Economic Minerals, published at Toronto by Warwick & Sons, 72 pages, a reprint of the Ontario Royal Commission on the Mineral Resources and Measures for their Development.
Commander H. W. Bayfield, Royal Navy, and Globular Concretions
It is possible that there is an even earlier reference to the Gunflint Formation stromatolites than Logan (1847). Many will be aware that both John Jeremiah Bigsby, M.D., and Commander H. W. Bayfield, Royal Navy, had explored the geology of the Thunder Bay area two decades before Logan, and that each published written reports of their findings. Bayfield reported on outcrops on islands at the east end of “Neepigon Bay” and mentioned greenstone that becomes more or less slaty, sometimes showing signs of stratification, and that it “sometimes contains globular concretions not unlike those observed in the greywacke of the St. Lawrence.” It is hard to tell what he meant by ‘globular concretions’. Interestingly, Hoffman (1969) included a map in his paper on which he plotted the location of Animikie (Gunflint) stromatolites and Sibley Formation stromatolites, and shows Gunflint stromatolites at the east end of Nipigon Bay. Bayfield’s ‘globular concretions’ could be stromatolites.
Bayfield, H. W., 1829, Outlines of the Geology of Lake Superior, Transactions of the Literary and Historical Society of Quebec, Volume 1, pages 1-43 at pages 20-21
Was John Jeremiah Bigsby, M.D., the first to promote what we now call stromatolites as evidence of life in the Precambrian?
John Jeremiah Bigsby, M.D.(1792-1881) – Geologist, Physician, Entomologist, Author and Artist– is no stranger to those with an interest in the geology of Canada. Before Sir William Logan and before Elkanah Billings arrived on the scene, John Jeremiah Bigsby was considered the person most knowledgeable on the subjects of geology and paleontology in the two Canadas. In the years 1820 -1826 he was the medical officer attached to the British party settling the boundary between the United States and British North America, and studied the land surrounding Lake Huron and Lake Superior. While Bigsby reported on the geology at the outlet of the Kaministiquia River into Lake Superior I’ve not been able to find that he reported concretions near Thunder Bay or that he reported on the geology along the Kaministiquia . This may have been because during the summer or 1823 the Americans were instructed to go out from Fort William and up the Kaministiquia River to Lake of the Woods, while the British party (including Bigsby) took the Pigeon River- Grand Portage route from Fort William. (See Epic Wanderer: David Thompson and the Mapping of the Canadian West, By D'Arcy Jenish, 2009, Bison Books, at page 228)
However, Bigsby may have been one of the first to promote what we now call stromatolites as evidence of life in the Precambrian, when he reported on an interesting structure in metamorphic rocks of what we now call the Grenville Province, Canadian Shield. In an article published in 1864 Bigsby reported that he had found on the North shore of the St. Lawrence, at the base of Cape Tourment, 36-40 miles below Quebec City, in close-grained quartzose gneiss, “a circular, cup-like, organic (?) body, two or three inches in diameter, with much the look, as well as the size, of a Maclurea [a large gastropod], not, however, with gyrations, but with concentric rings, one within another; the summits are rounded and not sharp-ridged; no radiating striae nor reticulations were observed in it, but they may exist. It might be very loosely compared to Spongarium interlineatum, or to a Chaetetes ... It is probably organic; and Sir W. Logan intends to examine the locality carefully. Near this fossil (?) And for some hundred yards around, the gneiss....” Unfortunately, I’ve found no further reference to this structure.
Bigsby, J. J., 1864, On the Laurentian Formation, Part II, The Geological Magazine, Volume 1, pages 200 -206 at page 205 http://www.biodiversitylibrary.org/item/97056#page/238/mode/1up
The main thrust of Bigsby’s article on the Laurentian Formation is that because there is evidence of carbon, phosphorus, lime etc. in Precambrian rocks there should be evidence of life, noting for carbon that “This substance is indispensable to organic structure, and is in very great quantity in the Canadas, almost always near to, or imbedded in, marble, which is often at the same time high in phosphate of lime, and contiguous to deposits of magnetic oxide of iron. ... Four of the principal constituents of life are thus brought together in the Laurentian Group; and with every probability that they have been employed as such.” His article has been largely ignored.
James Richardson’s 1872 Report of Spheroidal Masses and a Structure Resembling Coral
In the 1870 field season Mr. James Richardson of the Geological Survey of Canada explored the country north of Lake St. John, Quebec and described the geology from Lake Abatagomaw to Lake Wakinitchie, including near Lake Chibougamau. Today we would call the rocks that Mr. James Richardson examined the Superior Province of the Canadian Shield. Near a bay at the north end of Lake Abatagomaw he mentioned “there are considerable exposures of flattened spheroidal or reniform masses, from a few inches to upwards of a foot in diameter. They are made up of an indurated greenish and purplish argillaceous rock, which is jaspery in its texture. When sections of these spheroids have been exposed to the weather, they present a concentric arrangement of various shades of colour, becoming lighter towards the center.” Past Lake Chibougamau Mr. Richardson reported on “a blackish limestone, about a foot thick, interstratified with serpentine. Dr. Hunt, while examining these rocks, had a portion of the limestone sliced for examination under the microscope, which revealed a structure resembling that of some coral....This Mr. Billings thinks, is a coral, but not determinable generically.”
Richardson, James, 1872, Report on the Country North of Lake St. John, in Geological Survey of Canada, Report of Progress, 1870-1871 at pages 292 and 293
In the 1884 field season A. P. Low of the Geological Survey of Canada examined the rocks near Lake Chibougamau that has been examined by Mr. Richardson and the rocks around Lakes Mistassini and Mistassinis. He reported: “The lower beds resting unconformably on the gneiss, at the western end of Lake Mistassini, are made up of a dark bluish-grey limestone, holding concretionary masses of dark blue chert, with thin bands of black argillaceous shale. Above this are thin beds of light blue fine-grained dolomitic limestone, weathering yellow, interbedded with thin layers of a gritty limestone, containing large quantities of sand. .... Although closely examined, none of the above beds gave any evidence of fossil remains, the supposed fossils found by Mr. Richardson having, on closer examination, proved to be only mineral concretions.”
Low A. P., 1885, Report of the Mistassini expedition, 1884-5, Geological and Natural History Survey of Canada, Annual Report, Volume 1, (1885), Part D, at page 32D
Over a century after Mr. Richardson’s report, H.J. Hofmann commented: “Stromatolites were first reported from the Lake Mistassini area of Central Quebec more than a hundred years ago (Richardson 1872) and most subsequent geological reports make mention of them.... Illustrations accompanying a few of these reports show stratiform, nodular, domal and short columnar types...”
Hofmann H. J., 1978, New stromatolites from the Aphebian Mistassini Group, Quebec; Canadian Journal of Earth Sciences, v. 15, no 4, 571-585, at page 571.
www.nrcresearchpress.com/doi/abs/10.1139/e78-062
Calcareous Bunches, Keratose Sponge and Snow-shoe Tracks at Vermilion Lake near Sudbury, and Similar Rocks in Minnesota that Remind one of Cryptozoon
During the summer of 1889 the Toronto meeting of the Geological Association of America afforded Professor N. H. Winchell, state geologist for Minnesota, the opportunity to look at the rocks of Northern Ontario with Dr. Bell and Dr. Selwyn of the Geological Survey of Canada. At Vermilion Lake, at the crossing of the Vermilion river, about 30 km west of Sudbury, Winchell (1889) reported of a fine grained black slate that “In it are some curious calcareous bunches, or “concretions”, which recall the soft masses in which Dr. T. Sterry Hunt reported evidence of
keratose sponge, found near Thompson, Minnesota. Some of these masses are two feet in diameter, with rounded outlines, presenting on the weathered or glaciated natural surface a striking contrast with the rock that encloses them. They are locally designated “snow-shoe tracks”.” While true concretions have been reported from the Chelmsford Formation along Highway 144 about 4 kilometers north of Vermilion Lake, I believe that Winchell’s concretions/snow-shoe tracks are stromatolites from the Onwatin Formation or Vermilion Formation, in part because of his comments below.
Winchell, N. H., 1889, Further Observations on the Typical Huronian, and on the Rocks About Sudbury, Ontario, in Report for 1889, Eighteenth Annual Report, Geological and Natural History Society of Minnesota, at page 54
In 1890 field season Dr. Winchell reported his examination of slates near Northern Pacific Junction, Minnesota and reported finding structures similar to those that he had observed at Vermilion Lake near Sudbury. This time he remarked on the prevalence of the “dark calcareous lumps or secretions. These are the same that Drs. Hunt and Dawson supposed to contain traces of a keratose sponge, and which Dr. Selwyn pointed out as “snow-shoe tracks” – so called by the Indians– where their weathered contour- appear on the slates of the Vermilon River. ... When these lumps are fresh they are gray, crystalline apparently consisting essentially of lime, in which, in some parts, the small crystals of calcite are visible in compacted marmorized structure. But there is a layered, concentric, rather coarse structure reminding one of Cryptozoon, across which perpendiculary there is a transverse jointage...”.
Winchell, N. H., 1893, Field Notes of N. H. Winchell, in Report for the year 1891, Twentieth Annual Report, Geological and Natural History Society of Minnesota, at page 29-30.
Arthur Harvey – Animikie Cannon balls and Pelotechthen Balanoides
In April, 1889 Arthur Harvey delivered a paper before The Canadian Institute on the geology northwest of Lake Superior in which he mentioned that the rocks in the Lake Superior country “seem to contain no fossils, unless the “cannon balls” of the Animikie slates be such.” He did note that “the presence of particles of graphite and phosphate and the collection of iron into enormous beds seem to lead to the belief that the epoch of their formation was not anterior to the existence of life upon the world.”
Harvey, Arthur, 1889, Broad Outlines of the Geology of the Northwest of Lake Superior, Proceedings of the Canadian Institute, Third Series, Volume VI, 218-225 at 235
In November, 1889 Arthur Harvey delivered a paper before The Canadian Institute in which he mentions the Animikie formation’s locally called “cannon-balls”, which he named “Pelotechthen Balanoides– an acorn-shaped thing, grown in or from mud.” He commented “The uniformity of shape proves these things to be a growth; they are sometimes like an orange, often ovoid, and they so often have a slight protuberance on the upper side that I compare them rather to acorn than to an orange or an egg. Their internal structure, too, proves them a growth... [T]here is a very regular layer of pyrites around the nodule... This pyritous ring I have never failed to notice.... I submit that no mere mineral nodule would attain the size of many of these spheroids. I would have thought this growth a protospongia, except for the conditions under which it seems to have lived, that is if it be a zoophyte. .... [T]hey are from the bigness of a hen’s egg to that of a coal scuttle.”
Harvey, Arthur, 1891, Pelotechthen Balanoides, Transactions of the Canadian Institute, Volume 1, pages 213-215
I’ve found no reference where anyone else mentions Pelotechthen Balanoides.
PALEOZOIC ROCKS
Logans and Murray’s 1852 Reports on Concretions in the Paleozoic Rocks of Eastern Ontario
In the 1851 field season W.E. Logan and Alexander Murray of the Geological Survey of Canada examined the Paleozoic rocks comprising the country lying between the Ottawa River and the St. Lawrence River, from the junction of the two rivers (just west of Montreal) “to the neighborhood of Bytown on the one and Kingston on the other.” They reported on numerous concretions–structures that we would now identify as stromatolites. Here is part of Mr. Logan’s report on the Calciferous beds from Carillon to Grenville:“Immediately beneath the two-feet bed of limestone there is a singular and extensively spread concretionary layer, in some exposures of which, surfaces of half an acre shew the concretions, consisting of concentric layers, cut in half and closely packed together, some of them being two to three feet in diameter.”
Logan, W. E., 1852, Geological Survey of Canada, Report of Progress for the Year 1851-52, at page 19.
Here is part of Mr. Murray’s report:
“At Battle Windmill, a little over a mile below Prescott, the following descending section was measured:--
Pale grey arenaceous impure limestone, weathering bright yellow, and rapidly disintegrating on exposed surface; the bed is filled with concentric concretionary balls, the concentric layers of which are frequently interlined with white calc-spar... 1 ft, 2 inches”
Alexander Murray, 1852, Report of Andrew Murray, Assistant Provincial Geologist, Addressed to W. E. Logan, Provincial Geologist, in Logan, W. E., 1852, Geological Survey of Canada, Report of Progress for the Year 1851-52, pages 58 - 91, at pages 67-68.
Both of those reports were repeated in Logan, W. E., 1863, Geology of Canada, Geological Survey of Canada, Report of Progress from its Commencement to 1863, 983 pages, in his discussion of the Calciferous Formation (in Lanark county, now the March and Oxford) and Chazy Formations. When discussing the Calciferous, Logan mentions (at pages 112-113) that “On this part of the Ottawa [River at Rigaud] the middle portion of the formation is concealed; but the summit is met with on the bank of the river above Carillon, where about a hundred feet of arenaceous limestone and bituminous calcareous clay-stone terminate in a singular and extensively spread concretionary layer, like that noticed in the section below Prescott. In some of the exposures of it on the Grenville canal, about a mile below Grenville village, surfaces of half an acre shew the concretions, consisting of concentric layers seemingly cut horizontally in half and packed closely together, some of them being two to three feet in diameter.”
When discussing the Chazy formation Logan mentions (at page 134) “ Yellowish-grey concretionary limestone, weathering yellowish-brown; the concretionary masses are from six to 18 inches in diameter, and the concentric layers of the concretions thin” and (at page 174) “Black shale supplied in abundance with a coral, of which the specimens have been lost; the upper part holds large concentric concretionary nodules of fine grained black limestone, passing in parts into a bed of black limestone eight inches thick.”
Bernstein (1992) provides the most easily understood analysis of Logan’s Calciferous formation (breaking it into Theresa, a middle Beauharnois, and an upper Carillon), and includes a schematic cross-section, Figure 2, entitled “Generalized lithostratigraphy of the Beekmantown Group in the St. Lawrence Lowlands, Quebec and Ontario” showing the location of domal and columnar stromatolites in the various formations. He also includes a photograph with the caption “Geologist stands on exhumed, large domal stromatolites similar to those described by Logan (1852, 1863) and referred to as Cryptozoon by Grabau (1936).”
Bernstien, L, 1992, A revised lithostratigraphy of the Lower-Middle Ordovician Beekmantown Group, St. Lawrence Lowlands, Quebec and Ontario, Canadian Journal of Earth Sciences 29, 2677-2694 (1992)
Wilson and Wilson - Cryptozoon and Concretions in the Oxford Formation of Eastern Ontario
In earlier blog postings I mentioned the following two publications of the Geological Survey of Canada:
Wilson, Morley E., 1924, Arnprior-Quyon and Maniwaki Areas, Ontario and Quebec, Geological Survey of Canada, Memoir 136, 152 pages.
Wilson, Alice E., 1946, Geology of the Ottawa-St. Lawrence Lowland, Ontario and Quebec,
Geological Survey of Canada, Memoir 241, 66 pages.
Both publications provide photographs of what we now call stromatolites. Interestingly, while Dr. Morley Wilson wrote the earlier paper, he was the one more willing to consider the structures as being algal growths. Dr. Alice E. Wilson was in doubt as to whether the structures were concretions or algal growths.
Below is Dr. Morley Wilson’s a photograph of outcrop of Beekmantown dolomite exhibiting Cryptozoon, lot 21, Concession X, Fitzroy Township, Carleton County, Ontario – his plate VIII.
That photograph was taken in 1917 by Dr. Morley Wilson when he conducted field work in the Arnprior-Quyon area. Dr. Morley Wilson commented (at page 45) that “Most of the typical Cryptozoon are a few inches to 18 inches in diameter, but in places somewhat similar, flat, concentrically domed masses are present that attain a diameter of several feet. As seen in horizontal cross-section on the surface of an outcrop the Cryptozoon are circular in form (Plate VIII), but where they are exposed in vertical section they are generally considered flattened and dome-shaped.”
Below is photograph 81893 that Dr. Alice E. Wilson included in Memoir 241 published in 1946.
Cryptozoon Structures in the Nepean Sandstone/Potsdam Sandstone
In my November 4, 2015 blog posting I mentioned that in 1924 Dr. Morley E. Wilson of the Geological Survey of Canada had reported that an outcrop of Nepean Sandstone northwest of Ottawa “exhibits concentric ridge forms up to 8 inches in diameter, somewhat similar in appearance to the Cryptozoon structure seen in the Beekmantown dolomite farther to the eastward.” I also mentioned that within the last two decades numerous authors have reported stromatolites in the Potsdam Group sandstone (the upper formation of which is the Nepean).
There were many early reports of concretions in the Potsdam sandstone. Many are associated with the cylindrical structures that are considered to be dewatering structures resulting from springs. The concretions associated with the cylindrical dewatering structures (e.g., those reported at Rossie, New York by Franklin Hough (1853), or those that Dr. Selwyn looked at near Kingston –see Anglin, Boyle and James (1888)) could easily have formed by water circulating from the dewatering structures. However, there are many other early reports of concretions in the Potsdam from Ontario and New York State. For example, Logan (1863) mentions (at page 92) a two foot layer of “Blood-red coarse sandstone with concretionary nodules” near Charleston village. I suspect that some of the early reports of concretions could be stromatolites.
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I found it interesting to look back to see how stromatolites were first identified by early geologists and to see how many different common names were used before the term stromatolite was settled on. I have not mentioned all of the names that my research uncovered, as I’ve restricted this posting to localities in Canada or in the Canadian Shield. I have also not covered the proliferation of scientific names that erupted following Hall naming Cryptozoon in 1883.
Christopher Brett
Perth, Ontario
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1. In 1847 Logan and Murray spelt the river’s name as Kamanitiquia; in 1863, Logan spelt it as Kaministiquia. Bell spelt it Kaminitiquia. It is now spelt Kaministiquia. Murray, Logan and Bell refer to the falls on the Kaministiquia River as the Grand Falls. It is now called the Kakabeka Falls. Bell’s Lake Ka-zee-zee-kitchi-wa-ga-mog is now the pedestrian Loch Lomond. I have not been able to determine the current name for Sucker Brook.
2. Photographs of stromatolites in the Thunder Bay area can be found on the following web pages:
http://www.jon-nelson.com/stromatolites-in-thunder-bay-area#more-344
http://www.mindat.org/sitegallery.php?loc=222478
http://www.mindat.org/sitegallery.php?loc=222731
https://www.geocaching.com/geocache/GC31G74_kakabekia-a-living-fossil
Tuesday, 26 January 2016
Fluvio-glacial Sculpted Forms in Outcrops Near Newboro, Eastern Ontario
Geologists and geographers who study glacial eroded features in bedrock can distinguish between: (a) features which are formed by boulders, gravel and sand trapped under the glacial ice that abrade the bedrock as the glacier pushes and pulls the boulders, gravel and sand along; and (b) grooves and sculpted forms that have been cut into the bedrock by sediment laden, subglacial, meltwater flow. Glacial striae and chatter marks are examples of the former, while cavettos, potholes, spindles, v-shaped grooves, Sichelwannen, and Muschelbrüche are examples of the latter.
Below are photographs that I took of outcrops of sandstone a few kilometers east of Newboro, Eastern Ontario along the north side of County Road 42. The first three photos show spindle flutes and possibly Cavettos cut into the bedrock. Also of interest is the sharp rim (or ridge) at the top of the outcrop that is visible in the third photo. The fourth photo shows potholes or troughs.
I believe that these eroded features were caused by sediment laden, subglacial, meltwater flow, rather than by abrasion caused by boulders, gravel and sand trapped under and carried along by the glacier.
Below I’ve provided a number of articles that are worth a look if you are interested in meltwater eroded sculpted forms.
Christopher Brett
Perth, Ontario
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John Shaw, 1988
Subglacial erosional marks, Wilton Creek, Ontario
Canadian Journal of Earth Sciences, 1988, 25(8): 1256-1267
http://www.nrcresearchpress.com/doi/pdf/10.1139/e88-121
David R. Sharpe and John Shaw, 1989
Erosion of Bedrock by subglacial meltwater, Cantley, Quebec;
Geological Society of America Bulletin, Volume 101, p. 1011-1020
http://mysite.science.uottawa.ca/idclark/quat2333/labs/cantley/cantley_sharpe.pdf
Philip S.G. Kor, David R. Sharpe and John Shaw, 1991
Erosion of bedrock by subglacial meltwater, Georgian Bay, Ontario: a regional view;
Canadian Journal of Earth Sciences, volume 28, 623-642. DOI: 10.1139/e91-054
http://www.nrcresearchpress.com/doi/pdf/10.1139/e91-054
John Shaw, 1994
Stop 6: Large-scale bedrock fluting, Elginburg; Stop 7: Meltwater erosional marks, Wilton Creek (Thorpe Pit); Stop 12: Meltwater erosional marks, Marysville; in A field guide to the glacial and postglacial landscape of southeastern Ontario and part of Quebec, Robert Gilbert, compiler, 1994
Geological Survey of Canada Bulletin 453, 80 pages; doi:10.4095/194483
http://geoscan.nrcan.gc.ca/starweb/geoscan/servlet.starweb?path=geoscan/fulle.web&search1=R=194483
Philip S.G. Kor and Daryl W. Cowell, 1998
Evidence for catastrophic subglacial meltwater sheetflood events on the Bruce Peninsula, Ontario
Canadian Journal of Earth Sciences, 35(10): 1180-1202, 10.1139/e98-067
http://www.nrcresearchpress.com/doi/abs/10.1139/e98-067#.VqFFyk9c9K0
Mandy J. Munro-Stasiuk, Timothy G. Fisher and , Christopher R. Nitzsche, 2005
The origin of the western Lake Erie grooves, Ohio: implications for reconstructing the subglacial hydrology of the Great Lakes sector of the Laurentide Ice Sheet; Quaternary Geology Reviews, vol. 24, 2392-2409
http://www.eeescience.utoledo.edu/Faculty/fisher/Fisher/Publications_files/MunroStasiuk_etal_QSR05.pdf
Below are photographs that I took of outcrops of sandstone a few kilometers east of Newboro, Eastern Ontario along the north side of County Road 42. The first three photos show spindle flutes and possibly Cavettos cut into the bedrock. Also of interest is the sharp rim (or ridge) at the top of the outcrop that is visible in the third photo. The fourth photo shows potholes or troughs.
I believe that these eroded features were caused by sediment laden, subglacial, meltwater flow, rather than by abrasion caused by boulders, gravel and sand trapped under and carried along by the glacier.
Below I’ve provided a number of articles that are worth a look if you are interested in meltwater eroded sculpted forms.
Christopher Brett
Perth, Ontario
+++++++++++++++++++++++++
John Shaw, 1988
Subglacial erosional marks, Wilton Creek, Ontario
Canadian Journal of Earth Sciences, 1988, 25(8): 1256-1267
http://www.nrcresearchpress.com/doi/pdf/10.1139/e88-121
David R. Sharpe and John Shaw, 1989
Erosion of Bedrock by subglacial meltwater, Cantley, Quebec;
Geological Society of America Bulletin, Volume 101, p. 1011-1020
http://mysite.science.uottawa.ca/idclark/quat2333/labs/cantley/cantley_sharpe.pdf
Philip S.G. Kor, David R. Sharpe and John Shaw, 1991
Erosion of bedrock by subglacial meltwater, Georgian Bay, Ontario: a regional view;
Canadian Journal of Earth Sciences, volume 28, 623-642. DOI: 10.1139/e91-054
http://www.nrcresearchpress.com/doi/pdf/10.1139/e91-054
John Shaw, 1994
Stop 6: Large-scale bedrock fluting, Elginburg; Stop 7: Meltwater erosional marks, Wilton Creek (Thorpe Pit); Stop 12: Meltwater erosional marks, Marysville; in A field guide to the glacial and postglacial landscape of southeastern Ontario and part of Quebec, Robert Gilbert, compiler, 1994
Geological Survey of Canada Bulletin 453, 80 pages; doi:10.4095/194483
http://geoscan.nrcan.gc.ca/starweb/geoscan/servlet.starweb?path=geoscan/fulle.web&search1=R=194483
Philip S.G. Kor and Daryl W. Cowell, 1998
Evidence for catastrophic subglacial meltwater sheetflood events on the Bruce Peninsula, Ontario
Canadian Journal of Earth Sciences, 35(10): 1180-1202, 10.1139/e98-067
http://www.nrcresearchpress.com/doi/abs/10.1139/e98-067#.VqFFyk9c9K0
Mandy J. Munro-Stasiuk, Timothy G. Fisher and , Christopher R. Nitzsche, 2005
The origin of the western Lake Erie grooves, Ohio: implications for reconstructing the subglacial hydrology of the Great Lakes sector of the Laurentide Ice Sheet; Quaternary Geology Reviews, vol. 24, 2392-2409
http://www.eeescience.utoledo.edu/Faculty/fisher/Fisher/Publications_files/MunroStasiuk_etal_QSR05.pdf
Tuesday, 29 December 2015
More Evidence of Microbial Mats in Potsdam Sandstone near Newboro, Eastern Ontario
Winter has arrived in Eastern Ontario. Eight centimeters of snow fell last night and more is forecast for today. I’m glad that on December 26th I took the opportunity offered by the absence of snow to revisit the area around Newboro and to look at outcrops near Westport. I’d wanted to check for glacial meltwater eroded outcrops (and found some) and wanted to look again for further evidence of microbial mats. Below I report on three outcrops near Newboro. The first two outcrops are mapped as Potsdam Group sandstone. All of the outcrops are about four kilometers south of the Rideau Lakes Fault.
The silver ruler in the following photographs is one meter (39 inches long). The blue ruler is 12 inches (30 cm) long.
This is one of the outcrops from my last blog posting, the one mentioned under the subheading
‘Biofilm Structures’ where I provided two photographs showing a bedding parallel view of distorted laminations in quartz sandstone. Below are photographs of additional distorted sandstone laminations visible at this outcrop. The structures are difficult to envisage in sandstone unless the beds were bound by microbial mats. The first photograph may show a mat roll up structure.
Below are photographs showing a distorted bed that is up to about 12 inches (30 cm) thick contained within a sequence of flat lying beds of sandstone.
This distorted bed contains broken, folded and crinkled layers, plus layers that appear to have been thrust over or under other layers. I believe that this distorted bed represents pre-lithification distortion of biomats and stromatolitic layers in the sandstone, probably caused by seismic activity along the Rideau Lakes Fault. Seismic activity caused rupturing and folding of the unconsolidated sediment, but the biofilms preserved the laminations in the strata.
The mechanism that I have proposed to account for the 30 cm wide distorted bed near Newboro is analogous to the model proposed by Donaldson and Chiarenzelli (2004) to account for the meter thick convoluted layer in the Nepean sandstone outcrops in Kanata, Ontario, photographs of which were included in my November 4, 2015 blog posting. Both outcrops display soft-sediment deformation in sandstone, where seismic activity is the likely cause of the deformation.
I’ve included this outcrop because it has weathered in such a manner that it looks like the outcrop in Kanata, in a field off the Old Quarry Trail, photographs of which were included in my November 4, 2015 blog posting. It is missing the convoluted folds shown at the outcrop in Kanata, but otherwise the pattern of weathering is the same. Both the outcrop in Kanata and this outcrop show repetitive, weathered out, thin layers in sandstone. Below are photographs of the side view and the top view of the outcrop near Newboro.
I did not have my rock pick or sledgehammer with me on the 26th, but pulled a piece off the third outcrop, took it home, and cracked it with a small sledge. It’s sandstone, badly weathered sandstone, but sandstone.
Christopher Brett
Perth, Ontario
+++++++++++++++++++++++++++++++++++++++++
Addendum (January 5, 2016):
In the comment below Howard Allen of Calgary has suggested that the second outcrop may represent evaporite accumulation, subsequent solution and collapse. Others have reported on evaporites in Potsdam sandstone, and have suggested that they are responsible for observed structures in the sandstone.
Wolf and Dalrymple (1984) mention that “At one locality near Phillipsville, a zone of disrupted laminae caps the burrowed beds. The nature of the laminae suggests collapse into small cavities. .... The disrupted laminae which cap the cycle at the Phillipsville locality may represent the collapse of overlying sand into cavities formed by the dissolution of evaporites, such as gypsum or halite (B.W. Selleck, Colgate University, personal communication, 1983).”
Wolf and Dalrymple (1985) mention that “the tops of cycles are disrupted by soft-sediment deformation, due either to the leaching of evaporites or to (earthquake induced?) liquifaction. ....Evaporite moulds in one outcrop of this facies near Gananoque... give evidence of elevated salinities, a finding that is compatible with an evaporite-solution origin of the soft-sediment deformation features.”
Donaldson and Hilowle (2002) report for an outcrop of quartz arenites of the Nepean Formation in Kanata that they observed “evaporite pseudomorphs, including silica-replaced rosettes of barite and/or gypsum” and “a distinctive unit of synsedimentary breccia inferred to have formed in response to dissolution of a layer of bedded evaporites”.
Donaldson and Chiarenzelli (2004) suggest, for one of the outcrops of Potsdam sandstone (Nepean Formation) at Kanata, that “a few beds that stand out as glassy markers display abrupt truncations (Figure 6), suggesting that they may have been penecontemporaneously cemented, and then locally disrupted by erosional undercutting of unconsolidated substrate, localized upwards pressure associated with dewatering, or dissolution of intercalated evaporites.”
Sanford and Arnott (2010) reported that the “Imperial Oil Ltd., Laggan No.1 borehole encountered numerous gypsum interbeds throughout the upper half of the Nepean Formation.” In addition they noted that “Fairly extensive brecciation in the GSC Lebreton No.1 borehole, and to a lesser extent in the GSC Russell No.1 borehole, might also suggest the initial presence of minor halite in those areas, with subsequent dissolution and collapse.” Further, “The widespread paucity of normal marine fossils, except for local occurrences of trace fossils, represents evidence of elevated salinity throughout the Ottawa embayment. The occurrence of stromatolites, which can survive and even thrive in hypersaline conditions, is also a good indicator of evaporitic conditions.”
(Added: September 28, 2016)
David Lowe (2015, 2016), in his work on the Potsdam strata has recognized six siliciclastic paleoenvironments: (a) braided fluvial, (b) ephemeral fluvial, (c) aeolian erg, (d) coastal sabkha, (e) tide-dominated marine and (f) open-coast tidal flat. Wikipedia mentions that “Sabkhas are supratidal, forming along arid coastlines and are characterized by evaporite-carbonate deposits with some siliciclastics. Sabkhas form subaerial, prograding and shoaling-upward sequences .” The sabkha facies of the Potsdam Group are found in sandstone that in Ontario we call the Nepean Formation, in Quebec they call the Cairnside and in New York State they call the Keeseville.
The silver ruler in the following photographs is one meter (39 inches long). The blue ruler is 12 inches (30 cm) long.
First: An Outcrop Revisited
This is one of the outcrops from my last blog posting, the one mentioned under the subheading
‘Biofilm Structures’ where I provided two photographs showing a bedding parallel view of distorted laminations in quartz sandstone. Below are photographs of additional distorted sandstone laminations visible at this outcrop. The structures are difficult to envisage in sandstone unless the beds were bound by microbial mats. The first photograph may show a mat roll up structure.
Second: Distorted Layers in Flat Lying Beds of Potsdam Sandstone
Below are photographs showing a distorted bed that is up to about 12 inches (30 cm) thick contained within a sequence of flat lying beds of sandstone.
This distorted bed contains broken, folded and crinkled layers, plus layers that appear to have been thrust over or under other layers. I believe that this distorted bed represents pre-lithification distortion of biomats and stromatolitic layers in the sandstone, probably caused by seismic activity along the Rideau Lakes Fault. Seismic activity caused rupturing and folding of the unconsolidated sediment, but the biofilms preserved the laminations in the strata.
The mechanism that I have proposed to account for the 30 cm wide distorted bed near Newboro is analogous to the model proposed by Donaldson and Chiarenzelli (2004) to account for the meter thick convoluted layer in the Nepean sandstone outcrops in Kanata, Ontario, photographs of which were included in my November 4, 2015 blog posting. Both outcrops display soft-sediment deformation in sandstone, where seismic activity is the likely cause of the deformation.
Third: A Badly Weathered Outcrop
I’ve included this outcrop because it has weathered in such a manner that it looks like the outcrop in Kanata, in a field off the Old Quarry Trail, photographs of which were included in my November 4, 2015 blog posting. It is missing the convoluted folds shown at the outcrop in Kanata, but otherwise the pattern of weathering is the same. Both the outcrop in Kanata and this outcrop show repetitive, weathered out, thin layers in sandstone. Below are photographs of the side view and the top view of the outcrop near Newboro.
Christopher Brett
Perth, Ontario
+++++++++++++++++++++++++++++++++++++++++
Addendum (January 5, 2016):
In the comment below Howard Allen of Calgary has suggested that the second outcrop may represent evaporite accumulation, subsequent solution and collapse. Others have reported on evaporites in Potsdam sandstone, and have suggested that they are responsible for observed structures in the sandstone.
Wolf and Dalrymple (1984) mention that “At one locality near Phillipsville, a zone of disrupted laminae caps the burrowed beds. The nature of the laminae suggests collapse into small cavities. .... The disrupted laminae which cap the cycle at the Phillipsville locality may represent the collapse of overlying sand into cavities formed by the dissolution of evaporites, such as gypsum or halite (B.W. Selleck, Colgate University, personal communication, 1983).”
Wolf and Dalrymple (1985) mention that “the tops of cycles are disrupted by soft-sediment deformation, due either to the leaching of evaporites or to (earthquake induced?) liquifaction. ....Evaporite moulds in one outcrop of this facies near Gananoque... give evidence of elevated salinities, a finding that is compatible with an evaporite-solution origin of the soft-sediment deformation features.”
Donaldson and Hilowle (2002) report for an outcrop of quartz arenites of the Nepean Formation in Kanata that they observed “evaporite pseudomorphs, including silica-replaced rosettes of barite and/or gypsum” and “a distinctive unit of synsedimentary breccia inferred to have formed in response to dissolution of a layer of bedded evaporites”.
Donaldson and Chiarenzelli (2004) suggest, for one of the outcrops of Potsdam sandstone (Nepean Formation) at Kanata, that “a few beds that stand out as glassy markers display abrupt truncations (Figure 6), suggesting that they may have been penecontemporaneously cemented, and then locally disrupted by erosional undercutting of unconsolidated substrate, localized upwards pressure associated with dewatering, or dissolution of intercalated evaporites.”
Sanford and Arnott (2010) reported that the “Imperial Oil Ltd., Laggan No.1 borehole encountered numerous gypsum interbeds throughout the upper half of the Nepean Formation.” In addition they noted that “Fairly extensive brecciation in the GSC Lebreton No.1 borehole, and to a lesser extent in the GSC Russell No.1 borehole, might also suggest the initial presence of minor halite in those areas, with subsequent dissolution and collapse.” Further, “The widespread paucity of normal marine fossils, except for local occurrences of trace fossils, represents evidence of elevated salinity throughout the Ottawa embayment. The occurrence of stromatolites, which can survive and even thrive in hypersaline conditions, is also a good indicator of evaporitic conditions.”
(Added: September 28, 2016)
David Lowe (2015, 2016), in his work on the Potsdam strata has recognized six siliciclastic paleoenvironments: (a) braided fluvial, (b) ephemeral fluvial, (c) aeolian erg, (d) coastal sabkha, (e) tide-dominated marine and (f) open-coast tidal flat. Wikipedia mentions that “Sabkhas are supratidal, forming along arid coastlines and are characterized by evaporite-carbonate deposits with some siliciclastics. Sabkhas form subaerial, prograding and shoaling-upward sequences .” The sabkha facies of the Potsdam Group are found in sandstone that in Ontario we call the Nepean Formation, in Quebec they call the Cairnside and in New York State they call the Keeseville.
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