LAKES McGRUTHER & DELL – Muskoka District, Ontario, Canada – “Stratified circular feature”

Type: Stratified Circular Feature
Diameter: ~2.3 Km
Location: East of Parry Sound, Ontario N 45° 22.7’ W 79° 55.5’

The red dot indicates the position of LAKES McGRUTHER & DELL east of Georgian Bay, Ontario. – Google image

LAKES McGRUTHER & DELL – south (looking north) from my bird GOZooM.

An aerial survey for “circular” features was initiated by the Dominion Observatory in the 1950’s as a direct result from the Pingualuit crater study. It discovered many “hidden” impact structures, Brent and Holleford for example.

The study revealed two “semi-circular” lakes near Parry Sound, the largest of which forms a circle approximately 600 metres wide and is 4 to 10 metres deep. The “rib” of rock that divides the two lakes dips sharply to the south. Under a stereoscope the dished nature of the “crater” is striking. (McKean, 1964)

Further geological study revealed that this structure is NOT a meteorite impact crater; rather, it is the result of multiple folding episodes of the Grenville gneiss bedrock with subsequent erosion and glacial modification. It is classified as a “Stratified Circular Feature”. There are many features like this still visible in the Canadian Shield, an example is Lake Mecatina in eastern Quebec, a similar feature and will be a future exploration destination).

Reference

Gerencher, J. J.,(The Mecatina structure, NASA (grant NSF-473)

McKean, F.K. A Meteorite Crater in the Pre-Cambrian Shield Meteoritics, volume 2, number 3, page 243.