GLACIOLOGY: THE IMPACT OF SUBGLACIAL MELTWATER AT THE END OF THE ICE AGE
The sculpted bedrock landscape of the French River area of Georgian Bay, Ontario has attracted attention for many years. The suite of sculpted “s-forms” have been described individually in many locations and attributed to glacial erosion because they were closely associated with glaciated bedrock. However, the beautifully preserved Georgian Bay sites showed that these forms are analogous to erosional forms created by flow separations in fast moving water and are elements making up an integrated landscape (P. S. G. Kor, J. Shaw, D. R. Sharpe, 1991. Erosion of bedrock by subglacial meltwater, Georgian Bay, Ontario: a regional view. Canadian Journal of Earth Sciences, 1991, 28(4): 623-642). The role of the glacier is now seen to be as a confining medium generating extremely high velocity pressurised floods rather than a primary agent of erosion. Geodoxa has captured UAV (drone) imagery of the French River Delta providing unprecedented perspectives on the suite of landforms.
Fly over the sites with videos
KEY RIVER GIANT POTHOLES
HENVEY INLET POTHOLES
KEY PLUCKING ISLAND NORTH OF GERMAIN ISLAND
ISLAND EAST OF PUDDICK ISLAND
HENVEY INLET FLAT ISLAND
How to navigate 3D models:
- Mouse cursor: rotates the model
- Mouse wheel: moves away in/out
- Hold shift + mouse: side shifts
- Use full screen & wait for the HD rez.
In Summer 2017 we started a drone survey to study the geomorphology at a greater scales. We are glad to share some of our aerial imageries and photogrammetry 3D models.
A field trip to a small island, North of Germain island, was a key to interpret the hydraulic erosion on the lee side of rock drumlins. The presence of the conchoidal fracturing might reveal the existence of a process unknown til this day.
Photo by David Sharp
Rock Drumlins view from South - Lee side
High relief S-forms from vertical view
Giant sichelwannen looking at toss side
Looking southn - Rock drumlins topped by a giant sichelwanne - Notice de crest courge in the toss side of the drumlin
Rock drumlins - looking Norhward
Cavettos on a vertical wall - looking Southward
East of Puddick Island - Nadir view10
Vertical view of the very toss side of Germain Island - Notice the conchoidal shapes of the plucking on the lee side
Toss side of Germain Island - Notice the conchoidal shapes of the plucking on the lee side
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The island North of Germain Island had no name. Colleges are now calling it *Key Plucking Island*. Indeed this island shows clearly the traces of hydraulic plucking/hammering found mainly on the lee side of the rock drumlins. The site was a sort of "key" to comprehend this process.
East of Puddick Island - Nadir view
East of Puddick Island - A careful analysis of this image reveals how the subglacial water continues to smooth out the bedrock even after its fracturing or/and plucking.
East of Puddick Island
East of Puddick Island - Small cavitation few centimetres long
East of Puddick Island
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