In the Ohio hill, the granite did not break through, though the force of
the upheaval was such as to rend asunder the Devonian deposits, for we
find them lying torn and broken about the base of the hill; while the
Silurian beds, which should underlie them in their natural position,
form its centre and summit. This accounts for the great profusion of
Silurian organic remains in that neighborhood. Indeed, there is no
locality which forces upon the observer more strongly the conviction of
the profusion and richness of the early creation; for one may actually
collect the remains of Silurian Shells and Crustacea by cart-loads
around the city of Cincinnati. A naturalist would find it difficult to
gather along any modern sea-shore, even on tropical coasts, where marine
life is more abundant than elsewhere, so rich a harvest, in the same
time, as he will bring home from an hour's ramble in the environs of
that city.
These elevations naturally gave rise to depressions between themselves
and the land on either side of them, and caused also so many
counter-slopes dipping toward the uniform southern slope already formed
at the north. Thus between the several new upheavals, as well as between
them all and the land to the north of them, wide basins or troughs were
formed, inclosed on the south, west, and east by low hills, (for these
more recent eruptions were, like all the early upheavals, insignificant
in height,) and bounded on the north by the more ancient shores of the
preceding ages.
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