Geology Along the Lewis & Clark Trail

Geologic Points of Interest

Legacy of Ice

The route that was followed by Lewis and Clark was determined long before any human set foot in North America. The courses of the present Ohio and Missouri Rivers were dictated by the maximum extent of continental glaciers during the Pleistocene Epoch. Ancestral Missouri and Ohio tributary rivers predominately flowed northward into Canada, but when the glaciers moved southward during the ice ages, these rivers were re-routed to their approximate current paths flowing towards the Gulf of Mexico. It is these paths that dictated the route that the Corps of Discovery would ultimately follow.

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