"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 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.
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.
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.
+++++++++++++++++++++++
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
+++++++++++++++++++++++
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
