14 GEOLOGY OF OHIO. 
the trough has not been reached. The falls of the Ohio, formed by a 
rocky barrier across the stream, though at first sight seeming to disprove 
the theory of a deep continuous channel, really affords no argument 
against it; for here, as in many other instances, the present river does 
not follow accurately the line of the old channel, but runs along one 
side of it. At the Louisville falls, the Ohio flows over a rocky point 
which projects from the north side into the old valley, while the deep 
channel passes on the south side, under the lowlands on which the city 
of Louisville is built. | 
The tributaries of the Ohio exhibit the same phenomena. At New 
Philadelphia, Tuscarawas county, the borings for salt wells show that 
the Tuscarawas is running 175 feet above its ancient bed. The Beaver, 
at the junction of the Mahoning and Chenango, is flowing 150 feet above 
the bottom of its old trough, as is demonstrated by a large number of oil 
wells bored in the vicinity. Oil creek is shown by the same proofs to 
run from 75 to 100 feet above its old channel, and that channel had some- 
times vertical and even overhanging walls. 
An old channel of Mad river, now completely filled up, has been brought. 
to light by the railroad cutting at Springfield. It is described by Prof. 
Orton in his report on Clarke county, and I here reproduce his notes upon 
it, and the figure which illustrates them : 
** An old valley of Mad river is disclosed in the heavy cut of the Atlantic and Great 
Western Railway, from the river bridge westward to Col. Peter Sinz’s crossing. A 
sketch of the course of the river, and also of the railroads that cross it, is appended, 
by which the facts can be more readily understood. The tongue of land that occupies 
this bend of the river has an elevation of 100 feet to 125 feet above the level of the 
stream, and gives no hint in its contour of any break in the rocky floor underlying it. 
The Sandusky railroad (C. 8. & C.), which was first in order of construction, cuts 
across this tongue, as will be observed in the figure. A considerable portion of this 
cut is wrought in solid cliff rock, the maximum depth of the stone cutting being 18 
feet. With these facts before them, and guided also by the contour of the land, the 
Atlantic and Great Western Company, whose line crosses the river half a mile higher 
and on a grade of ten feet below the first road, expected also to find rock, and made 
arrangements for tunneling the hill. The route that they selected, however, chanced 
to be a buried channel of the river, which allowed an open cut of 65 feet through clay 
and sand, instead of a rock tunnel. Soundings that have since been made from the 
track to the level of the river show Drift materials through this whole extent. The 
dotted lines in the figure indicate the buried channel, whose general limits can be as- 
signed with a good degree of accuracy from the cliffs that remain and the soundings 
that have been made. 
‘“‘Tt will be observed that the old channel was much shorter and more direct than 
that which the river has since wrought out for itself, accomplishing in three-fourths 
of a mile the same advance that is now gained by two and one-half miles.” 
