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Abstract:
The remarks here submitted will be confined chiefly to that part of the Western States of North America watered by the rivers Ohio, Wabash, Illinois, Rock, Wisconsin, Cumberland and Tennessee, lying between the 35th and 43rd degree of N. latitude and the 81st and 91st of W. longitude. The district includes the states of Illinois, Indiana, Ohio, Kentucky, Tennessee, and the Du Buque and Mineral Point districts of Iowa and Wisconsin. This territory occupies an area of about half a million of square miles, but its geological features are remarkably uniform, belonging, with a few partial exceptions, to the periods of the bituminous coal and carboniferous limestone as found in Europe, and the Silurian rocks as described by Sir R. Murchison; the exceptions are the superficial deposits which occasionally cover up these from view over considerable tracts, and these must either be referred to the age of gigantic mammalia and formations of a much newer date, or belong to a marl and greensand found in the western district of Tennessee, probably a portion of the greensand and other members of the cretaceous group. A general idea of the geological formations of the whole tract may be obtained from the annexed diagram. ... This 250-word extract was created in the absence of an abstract