Gowgonda Formation - The
formation outcrops in Canada, just north of Michigan. This rock
is called a tillite, it was deposited many millions of years ago
as a glacial till. Millions of years later, when the glaciers
moved south during the last ice age, they picked up chunks of
Gowgonda rock and carried them into lower Michigan. This is a
good example of how the rock cyles works. First, the original
till was deposited, buried, and became lithified. Then the rock
was uplifted, exposed, and incorporated into another glacial till.
Gowganda rocks are quite easy to find in the glacial till deposits
(any gravel pit) around Grand Rapids.
