NOTES ON THE GEOLOGY OF YATES COUNTY, 1ST. Y. 



By Berlin H. Wright, Penn Yan, N. Y. 



Surface. 



The surface of Yates county is divided by five great ridges extend- 

 ing in a northwardly direction. These ridges gradually decline, from 

 a height of 600 to 1,800 feet above Seneca lake, to a gently un- 

 dulating region in the towns of Torrey, Benton, Potter and Middle- 

 sex. The first ridge is between West River hollow and Oanandaigua 

 lake, and ends in an abrupt promontory about 1,000 feet above the 

 valley beneath it, and about 1,780 feet above the level of Seneca lake. 



Explanation : — Section across Yates 

 to Dresden, on the west shore of Seneca lake. 

 Horizontal scale = 4% miles to 1 inch. 

 Vertical scale = 1,066 feet to 1 inch. 



1. Moscow shale, 100 ft. 



2. Tully limestone, 12 ft. 



3. Genesee slate, 150 ft. 



4. Portage group, 1,000 ft. 



4'. Stratum of gypsiferous limestone, \%! 

 thick. 



5. Chemung group. 



a. Level of Oanandaigua lake. 



b. West ridge. 



JV. Y., from the head of Oanandaigua lake 



c. West River hollow. 



d. Italy hill. 



e. Flint creek, Italy hollow. 

 /. Italy hill. 



£. Sherman's hollow. 

 . West hill. 

 i. Larzaliers' hollow. Valley of ancient 



outlet of Lake Keuka. 

 j. East hill. 



k Valley of E. branch of Lake Keuka, 331 

 ft. Former outlet of Lake Keuka. 



The next ridge eastward lies between West Eiver hollow and Flint 

 creek or Italy hollow, ending near Potter Centre, and in the southern 

 portion of the town of Italy presenting almost perpendicular sides and 

 rising quite as high as the one west of it. The next is called Italy 

 hill, and at its highest point, which is very near the middle of the 

 eastern boundary of the town, rises nearly as high as those west of it. 



