Geologically this region belongs to the great Canadian Shield of Pre-Cambrian Rock.
"In that part of northern Ontario and Quebec of which Lake Temiskaming is the geographic centre, a series of Pre-Cambrian classic sediments occur which are of peculiar interest to the geologist, not only because they form the country rock of the larger part of the rich silver bearing veins of the Cobalt Mining Camp. Their character are such as to indicate that they are entirely of terrestial origin and have been in part from continental glaciers.
" The Cobalt Series; Its Character and Origin, Morley E. Wilson, The Journal of Geology, Volume 21, No. 2 (Feb.-Mar. 1913); Morley E. Wilson, Canadian Geological Survey, Ottawa.
In geology, ripple marks are sedimentary structures, (i.e.: bed planes of the lower flow regime) and indicate agitation by water (current or waves) or wind. As such, they may be used in statigraphic studies to indicate the original position of strata in geologically complex terrain.
'Ripple Marks', simply defined, are wavy surfaces comprised of regularly alternating ridges of and hollows which commonly form at the contact between water and loose sediment. They are sculptured by current or wave action and can be used to determine the direction of transport and environment of deposition of sediments. These same features can be seen today at most beaches, streams and lake bottoms where waves or currents are active.
The thin claystone and siltstone layers at the base of this cliff are characterized by the presence of many of these near symmetrical ripple marks. These are the gentle curved lines visible on the rock face. The lines represent a slice cut through the ripple. One can see and feel the true shape of these structures on the flat bedding planes also exposed at this location. The ripple marks have been perfectly preserved for over two billion years and suggest that the sediments were transported in two different directions and deposited in a relatively deep lake.
Symetrical ripple marks are often located on beaches. They are created by a two way current. This creates ripple marks with pointed crests and rounded troughs.
Asymetrical ripple marks are created by a one way current. They create ripple marks with still pointed crests and rounded troughs but which are inclined more strongly in the direction of the current.
At this location, there is an opportunity to observe cross bedding in the bedding plane. Cross bedding can include ripples and dunes or any cross stratification caused by currents.
While here, please take the time to visit another Earthcache: GC5XYG8 - Cobalt's Silver Sidewalk.
To claim a find on this earthcache please email your answers to the following questions to me by using the email or message links located at the top of this earthcache description.
1. Using your GPS or a compass, what direction(s) did the ancient lake's currents flow in this area?
2. Estimate the height of the rock face at this location.
3. Describe in your own words the appearance and texture of the rock face and ripple marks.
4. What type of ripple marks do you believe you are viewing at this location.
References: Natural Resources Canada, and Ontario Geological Survey, 2015, 'Heritage Silver Trail, Cobalt Road Tour' -pamphlet.
The Cobalt Series, It's Character and Origin, Morley E. Wilson, The Journal of Geology, Volume 21, No. 2, February-March 1913, Morley E. Wilson, Canadian Geological Survey, Ottawa.
Wikipedia