422 GEOLOGY or OHIO. 



On the opposite side of the creek, and a mile or two further down, there 

 is a still more extended section of the same elements. It is found on the 

 farm of the Roberts' brothers. It does not deserve to be called a new ex- 

 posure, as the outcrop of the rock is scarcely interrupted from one point 

 to the other. 



A somewhat anomalous fact meets us in this section. There is inter- 

 polated in the Corniferous series a few inches of a very pure, saccarhoidal 

 sandstone. The occurrence of such a deposit at about this point in the 

 scale is not, however, named here for the first time. Rev. H. Herzer 

 reported several years since a similar deposit in the Corniferous at West 

 Liberty, Logan county, and Mr. Franklin C. Hill, in his report for the sur- 

 vey on this county, shows that sandstone holds the same relations there 

 that it has in Madison county. It is not found at the base of the Cornifer- 

 ous series in either instance, but itoccurs in thin beds distributed through 

 five or more feet of the limestone at an elevation of about fifteen feet 

 above the base of the series. It is underlain by undoubted beds of Corni- 

 ferous limestone and can not therefore, in these instances, be considered ' 

 as the southward extension of the Oriskany sandstone. It is rather the 

 counterpart of the Hillsboro sandstone which, in like manner, is inter- 

 jected into the Niagara series — in the southern part of the State. These 

 two aberrant sandstones furthermore agjee very closely in lithological 

 characters. 



The sand from the Roberts quarries has long been known throughout 

 the adjacent country and has even found its way as far as Columbus. 

 Whenever plastering of unusual excellence is attempted in this vicinity, 

 recourse is had to this deposit. The sandstone is nowhere more than six 

 inches in thickness and it lies between ledges of rock so heavy that it 

 can not be profitably obtained except when the quarry is worked for 

 other purposes. Its interest, in other words, if geological rather than 

 economical. 



These are the only known localities in Madison county in which the 

 bedded rock is exposed to view. On the extreme eastern edge of the 

 county, in Jefferson township, it has been ascertained in the driving of 

 wells that the rock lies about forty feet below the surface. There are a few 

 other points in the county in' which the underlying rocky floor has been, in 

 like manner reached, but these oases are of very rare occurrence. Borings 

 of fifty or even sixty feet are often made which do not exhaust the drift 

 beds. 



There is no region of the State in which the basement rock makes a 

 more insignificant show or exerts less infliuence upon the present sur- 

 face of the country. Even the details of th.e topography are seen to 



