3. CENTRE TO WIS SHIP. F 2 . 185 



sandstones. It usually shows itself as a ridge of rocks upon 

 the surface. The frosts and storms, the suns and rains of 

 the ages have split the solid rock into pieces and the same 

 process is still going on. The larger fragments are being 

 broken into smaller ones and the smaller ones into sand, 

 which is washed down and carried away by the river as fast 

 as it is formed. Nothing but their greater hardness has 

 saved them from the more rapid destruction which has been 

 the fate of all the softer beds in the vicinity. 



But, though thin, the Oriskauy sandstone is a conspicu- 

 ous feature in the geology of the township. The great 

 number of its outcrops renders its ridges very numerous 

 and in some places they seem almost in contact. The lat- 

 eral or tangential pressure to which I have alluded as the 

 cause of the foldings of the rocks was more severe, or, to 

 speak more accurately, the effects of its severity are more 

 apparent in Centre township than anywhere else in the 

 county. The beds of rock in many places stand vertical 

 and are sometimes overthrown. 



These facts may be best observed on Limestone ridge and 

 in Dick's hill and Iron ridge. As mentioned above the 

 limestone bed of wdiich these ridges consist is not more than 

 400 feet thick, including the adjoining shales. Conse- 

 quently as this bed, sharply folded and lying in a vertical 

 position, covers tracts of country sometimes half a mile 

 w T ide there must be many folds in that space. Now, every 

 fold of the limestone involves a fold of the overlying Oris- 

 kany sandstone. A geologist therefore would expect to 

 find a series of nearly parallel ridges crossing the county 

 at intervals ranging up to 700 or 800 feet. This is actually 

 the case, as may be "proved by any one who will take the 

 trouble to walk across Limestone ridge or Iron ridge at right 

 angles to the strike of the beds, or from N. N. W. to S. 

 S. E. (See sketch section, Plate XVI, page 176, Fig. 1.) 



Three complete folds of the Lower Helderberg limestone 

 and Oriskany sandstone are here shown. They are crushed 

 and pressed close together so that their sides are nearly par- 

 allel. The Oriskany sandstone is represented by the black 

 line on the top of the limestone. It is observed that this 



