Dr. Easton’s Sandstone Outcrop at Gillies Corners, Lanark County - Part 2

 I dropped over to look at Dr. Easton’s outcrop this week.  Below are two photographs (347 and 351) of the rounded, nodular pseudomorphs of evaporite minerals.  The nodules originally could have been any of gypsum, anhydrite, halite, barite, phosphate.

Below is a better photograph of Dr. Easton’s outcrop (356) showing the March formation at the top and the underlying Nepean formation.    

In addition below is a photograph (366) of a piece of the fine grained  buff sandstone that is arguably wind blown (aeolian erg) sandstone.  I wetted the sample so that the layering is visible.  The numbers on the blue ruler record centimeters.  

 

Another Outcrop on Malcolms Way

I also looked at an outcrop that is about 150 meters to the east along Malcolms Way.  Below are two photographs (359 and 362) showing the darker March formation on top and the underlying Nepean formation.  The  silver ruler is a meter stick with inches and centimeters numbered.

Christopher Brett
Ottawa

Addendum (September 15, 2020):  Another interpretation of the outcrops is that all of the rock is March (Theresa) formation.  This is because interbedded with typical March sandy dolomites and dolomites one finds beds of  siliceous sandstone identical to Nepean sandstone.   This can be seen in outcrops of the March (Theresa) formation at the outskirts of Smith Falls heading north on Highway 15. 

Interestingly, Keith’s map 1946-9 of the distribution of Potsdam sandstone in Eastern Ontario (which was in part based on mapping by Morley E. Wilson and by Alice E. Wilson)  shows an area of Potsdam sandstone where “Calcareous and argillaceous sandstone predominate”extending to Gilles Corners.  Some areas on Keith’s map where “Calcareous and argillaceous sandstone predominate” are now mapped as Potsdam Group sandstone and some as the March formation. 

SUGGESTED READING -  SABKHA NODULES

Bréhéret, Jean-Gabriel and Brumsack, Hans-J., 2000
Barite concretions as evidence of pauses in sedimentation in the Marnes Bleues Formation of the Vocontian Basin (SE France).  Sedimentary Geology 130(3):205-228  February 2000  
https://doi.org/10.1016/S0037-0738(99)00112-8
 
Butrenchuk, S., 1996
Phosphate Deposits  in British Columbia.  British Columbia  Geological Survey Branch., Bulletin 98, 136 pages
http://cmscontent.nrs.gov.bc.ca/geoscience/PublicationCatalogue/Bulletin/BCGS_B098.pdf
 
Fryberger, Steven G.; Abdulkader M. Al-Sari; Thomas J. Clisham, 1983 

Eolian Dune, Interdune, Sand Sheet, and Siliciclastic Sabkha Sediments of an Offshore Prograding Sand Sea, Dhahran Area, Saudi Arabia
AAPG Bulletin (1983) 67 (2): 280–312.
https://doi.org/10.1306/03B5ACFF-16D1-11D7-8645000102C1865D
 
Garden,U.R.; S.C.Guscott, S.D.Burley , K.A. Foxford, J. J. Walsh and J. Marshall, 2001
An exhumed palaeo-hydrocarbon migration fairway in a faulted carrier system, Entrada Sandstone of SE Utah.  Geofluids (2001)1, 195 -213
https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.1468-8123.2001.00018.x

Ge, Y.,  C. L. Pederson, S. W. Lokier, J. P. Traas, G. Nehrke, R. D. Neuser, K. E. Goetschl,
A, Immenhauser,  2020
Late Holocene to Recent aragonite-cemented transgressive lag deposits in the Abu Dhabi lagoon and intertidal sabkha.  Sedimentalogy, Volume67, Issue 5, Pages 2426-2454
https://doi.org/10.1111/sed.12707

Keith, M. L.,1946
Sandstone as a  source of silica sands in southeastern Ontario; Ontario Dept. Mines, Vol.55, pt.5, 36p. (published 1949). Accompanied by Map 1946-9, scale l inch to 2  miles

McMackin, Matthew and William Godwin, 2016
Sabkha, in Encyclopedia of Engineering Geology (pp.1-2),Editors: P.  T. Bobrowsky, B. Marker
DOI: https://doi.org/10.1007/978-3-319-73568-9_26
DOI: 10.1007/978-3-319-12127-7_248-1

West, Ian M., Y. A. Ali; M. E. Hilmy, 1979
Primary gypsum nodules in a modern sabkha on the Mediterranean coast of Egypt.
Geology (1979) 7 (7): 354–358.
https://doi.org/10.1130/0091-7613(1979)7<354:PGNIAM>2.0.CO;2

Zhou, X.,  D. Chen, S. Dong, Y. Zhang,  Z. Guo, H.Wei, H.Yue, 2015
Diagenetic barite deposits in the Yurtus Formation in Tarim Basin, NW China: Implications for barium and sulfur cycling in the earliest Cambrian. Precambrian Research  Volume 263, July 2015, Pages 79-87 https://doi.org/10.1016/j.precamres.2015.03.006 See Figure 3.