horizontal position. Through these comparatively horizontal strata the Ohio River has worn a gorge of remarkable uniformity, and several hundred feet in depth. Even to the ordinary observer it is clear that this trough is one of erosion; for the strata of rock upon one side of the river match those upon the other as precisely as do the two ends of a board which has been sawed apart. The seams of sandstone, coal, and lime rock upon one side correspond to similar seams upon the other; while the river does not pursue a straight course, but follows, throughout, a very tortuous channel, such as is begun by the meandering of a stream over a nearly level surface.
The width of this rocky gorge is from a quarter of a mile, where the rocks are peculiarly hard, to a mile or over, where they are more easily disintegrated. For the most part, also, the tributaries occupy corresponding gorges, with a width contracted to the proportion of the individual drainage basins. At the junction of the main stream with the tributaries there is usually an enlargement of the gorge such as would naturally follow from the combination of erosive forces which there occurs. These features of the trough of the Ohio and its tributaries give character to the scenery throughout its course. Nowhere from the decks of the steamer does one get an extended view on either side. Everywhere the vision is circumscribed by the hills, more or less precipitous, which rise close at hand upon both the right and the left; while the windings of the channel are such that no very distant views are obtained either before or behind. The railroads which connect the cities in the valley are compelled either to hug the side of the gorge between the river and the precipitous ledges, or to strike up some one of the tributaries, and then, after crossing the country for a while, follow down another to the level of the main stream. The land a little back from the trough of the river is very broken and hilly, since all the affluents of any size have eroded channels for themselves down to the depth of the principal gorge.
Above Louisville, Ky.,the large cities upon the Ohio strikingly reveal the limitations imposed upon them by the character of the river valley. Having begun as a cluster of houses upon the river's bank, they have gradually spread back upon it, until reaching the base of the rocky precipices. With the rapid growth both of population and of improvements in later years, Cincinnati and Pittsburg have literally overflowed their banks and risen to the summit of the hills on either side, the inhabitants being transported from their places of business to their residences by long inclines up which the street cars are drawn at a steep angle to a height of from three to five hundred feet, from which positions extended views are given in every direction over the
