by a tornado that had passed from west to east, and in its way cleared the ground almost entirely. The largest trees were either torn up by the roots or broken. In the part that I observed, nothing but underwood and the shattered fragments of trees remained. On making inquiries as to the hurricane, I was informed that it swept over the country to the length of several hundred miles; and that, on the Kentucky side of the river, it totally obstructed a road with timber which has not yet been removed.
It is also about thirty miles below the falls that the range of high land, called the knobs, intersects the river. This is the ridge that crosses the lower part of Indiana, and part of Kentucky, which the late M. Volney noticed under the name of the Silver Creek hills; and by him supposed to have once formed a dam, that retained a lake in the valley of the Ohio, extending from the ridge just mentioned, to the place where Pittsburg now stands. That philosopher attempted to show that the higher bottom lands, which are above the level of the present inundations, were deposited in the bottom of the lake; and that, on the water's making a gap in the barrier, the lake was drained, and the Ohio withdrawn into its present lower and less capacious bed. That the knobs once formed a dam I am forced to admit, from having seen marks on a high level on the limestone rocks in the gap, which {258} clearly indicate the action of a cataract: but I am, notwithstanding, led to agree with Dr. Drake's hypothesis, which explains the formation of the higher bottom land, as being the alluvion of the Ohio at a time when that river was much larger than at present. The facts relating to this subject that have come within the reach of my own observation, may perhaps be inserted in
