The Ohio river at Cincinnati, and immediately above and below it, is bounded on its right bank by two terraces, on which the city is built; the streets in the upper and lower part of it standing on different levels. These terraces are composed of sand, gravel, and loam, such as the river, if blocked up by some barrier, might now be supposed to sweep down in its current, and deposit in a lake. The upper terrace, b, (fig. 9.) is bounded by steep hills of ancient fossiliferous rocks, A, the blue, Lower Silurian limestone, mentioned in the last chapter, in horizontal stratification. The higher terrace, b, is about 60 feet above the lower, c, and this again about 60 feet above low water in the Ohio, d The geologists here are convinced that the inferior terrace, c, is of newer origin than b, as shown in the section (fig.9),and proved by excavations, not exposed at the time of my visit.

In sinking a well through c, at the distance of 300 yards from the Ohio, and at the depth of 50 feet from the surface, they found, at e, pieces of wood and many walnuts in a bed of silt.

Near the edge of the higher terrace, in digging a gravel-pit, which I saw open at the end of Sixth street, they discovered lately the teeth of the Elephas primigenius, the same extinct species which is met with in very analogous situations on the banks of the Thames, and the same which was found preserved entire with its flesh in the ice of Siberia.