

DESCRIPTION OF THE FORMATIONS. F\ 71 



broken, crushed, and distorted them often past recogni- 

 tion. 



The thickness of the Chemung rocks in this county dimin- 

 ishes rapidly from north to south. 



Above Newport they are, as nearly as I have been able to 

 determine, about 3300 feet thick. 



In the middle monoclinal outcrop no measurements could 

 be obtained. 



In the southern trough near Rockville the combined Gfen- 

 •essee-Portage-Chemung rocks measure only about 1100 feet. 



This indicates a diminution in a direct distance of about 

 fifteen miles of more than 2200 feet. 



It has proved impossible to determine, with the time and 

 means at my command, whether or not this diminution ex- 

 tends westward from the river. Extreme caution is re- 

 quired in obtaining these dimensions in Perry county. 

 Concealed folds, extension of anticlines, and the presence of 

 faults destroy the value of many exposures for this purpose. 



An instance in point occurs near Newport, where, by over- 

 looking the eastward extension of the fold at Inoculate run, 

 xi thickness has been assigned to the Genessee shales six 

 times too great, 1120 feet instead of 200 feet. 



In like manner at the end of the northern syncline a set 

 of small anticlinal folds run in from the west, flattening and 

 reversing the dip and rendering the measurement of thick- 

 ness impossible. 



The great expanse of the Chemung rocks is unfortunate 

 for the farmers of the county. Yielding by decomposition 

 a poor, thin soil, only good farming can render it produc- 

 tive. The poorest lands in the county, with some slight ex- 

 ceptions, are those upon the Chemung shales. This is es- 

 pecially conspicuous in the northern syncline on Middle 

 ridge and Hominy ridge, both of which are chiefly com- 

 posed of Chemung rocks. These have been cleared for the 

 most part, the former almost entirely, but in many places 

 have since been abandoned and are going back into wood- 

 land, being partially covered with a young growth of scrub 

 pine (P. ifiops,) a worthless kind of timber. 



The surface of the Chemung shales usually consists of 



