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