Geology of Cincinnati. 29 



gory, for in many places its valley is too wide and too deep to 

 have been excavated by the volume of water now flowing at ordi- 

 nary stages. In fact there seems little doubt but that the Ohio 

 flows in a channel which was cut long previous to the glacial 

 period. This old channel has been largely filled up, and the river 

 now flows from thirty five to forty feet above its ancient bed. 

 This seems to be conclusively proven by the discovery at that 

 depth below the present surface of the ground of an extensive bed 

 of carbonaceous material consisting of stumps of trees, leaves, 

 seeds, and other vegetable remains. This layer doubtless once 

 formed a sort of bottom land, and the material overlying it must 

 be referred to a later epoch and one which seems contemporan- 

 eous with the period of the glaciers. 



This superposed material, forming in main the terrace upon 

 which the city stands, is composed, according to Prof. Orton,* 

 " Of distinctly stratified gravel and sand of varying degrees of 

 fineness and purity. The gravel stones are all water-worn. In 

 weight they seldom reach ten pounds. The upper tributaries of 

 the Ohio supply the materials in part, but a much larger propor- 

 tion in the vicinity of Cincinnati is derived from the limestone 

 rocks of Western Ohio and the crystalline beds of Canada." "The 

 leading facts in the structure of the terraces show that their history 

 is not to be explained by the present conditions of the continent. 

 They must have been formed under water at a time when the face 

 of the country held a lower level than it does now by one hundred 

 or more feet." 



The gravel and sand of the terraces varies greatly in different 

 quarters. In some places, as has been revealed in excavations in 

 different quarters of the city, it is coarse and mostly composed of 

 large pebbles mixed with a small quantity of clay and sand. 

 Fourth street, Broadway, and many other streets are on gravelly 

 foundations. Again, the gravel is replaced by fine sand, as for 

 example on West Eighth street, near Mound, Vine, near Fifteenth, 

 and others ; while in still other places the subsoil is a heavy, stiff 

 clay, very close and fine grained and exceedingly difficult to work. 

 One pocket, as it seems to be of this material, is in the vicinity of 

 Pike and Pearl streets. It goes by the name of " Springfield clay." 

 It is this clay, so Prof. Orton states, which was used in paving the 

 floor of Eden Park Reservoir. These various deposits, sometimes 

 extremely local, show varying conditions existed ; in one place a 



*Ohio Geol., 1., p. 431. 



