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283 Ancient Changes of Level

While the Topographness of Ohio and Michigan are able to trace ancient lake beaches around lake Erie having an elevation of about one hundred and eight feet above he present surface of the water, we cannot find evidence [of illegible, crossed out] about Lake Michigan of such ancient elevation, but on the contrary there are some facts that tend to show that this lake was once lower than at present. The appearances about the mouths of every considerable stream [evince?], that they once were lower, wearing their beds some fifteen or twenty feet below the present surface of the water. The subsequent elevation of the lake has caused the water to set back on these rivers in some cases two or three miles causing deep pools of "back water" and affording convenient basins for the accomodation of shipping. In what other way could these river beds have been excavated to so great a depth? Surely the slight current at present seen could not have been the cause.

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