GKEENE COUNTY. 663 



hundred and twenty-five feet, making the total section of the rocks of 

 the county four hundred and twenty-five feet. 



The best general section for the study of the strata of the county— and 

 there is no better one for the same geological elements in the State— is 

 found in the valley of the Little Miami River and its tributaries, between 

 Goe's Station and Yellow Springs. At the first named point, Goe's Sta- 

 tion, the Little Miami is bedded in the limestones and shales of the Cin- 

 cinnati series. Fifty feet, at least, of this formation' are here shown on 

 the western side of the valley. The Xenia turnpike, the Little Miami 

 Railroad, and the race for the Powder Mills have all required rock-cut- 

 tings. The streams, also, that descend from the uplands have their 

 channels in the rock, so that the constitution and contents of the beds 

 can be fully studied. The fossils of this portion of the series abound in 

 these outcrops and sections. Among them are to be named Rhynchonella 

 capax, Trematospira modesta, Orthis occidentalis (upper variety), Stropho- 

 mena planumborta, and several of the corals. 



The termination of the Cincinnati series is very distinctly shown in 

 the ravine to the south of Mr. Goe's residence. This may, indeed, be 

 considered a typical locality, for it is from this very point that the phe- 

 nomena of the line of junction between the Lower and Upper Silurian 

 formations have, in part, been described. Between the fossiliferous beds 

 of the Cincinnati group and the overlying Clinton limestone there oc- 

 cur twenty to thirty feet of fine-grained shales in color, light blue or 

 red, and destitute of fossils. Occupying as do these shales the place held 

 by the Medina group to the eastward and northward, it has been sug- 

 gested that they are a representative of that period. They are not, 

 however, found at all sections of this horizon, the Clinton sometimes 

 resting directly upon the fossiliferous beds of the Cincinnati series. 



A fine display of the Clinton limestone is shown in the wall of rock 

 that immediately overhangs the shales above described. The same lime- 

 stone occurs in bold cliffs along the river valley, near Grinnell's Mill. 



From this last named point the section is prolonged by the Yellow 

 Springs branch, which shows, in the course of two miles, at least one 

 hundred feet of rock. The artificial sections of the Yellow Springs 

 quarries are now reached, which constitute, on the whole, the best point 

 in the county at which to study the Niagara series. 



There are other fine natural sections of the rocks of the county, but 

 the one now described may be taken as a fair sample of them all. 



The separate elements in the geological scale above given will now be 



briefly treated. 



1. The uppermost two hundred and fifty feet, or thereabouts, of the 



