GEOLOGIC MAP OF THE TULLY QUADRANGLE 



49 



Tully limestone 



This is the typical region of this interesting formation, and here 

 it attains almost its maximum thickness. The formation which is a 

 very important bench mark in the Devonic series extends from 

 here westward to within y 2 mile of the eastern shore of Canandaigua 

 lake, Ontario co. and from here eastward almost to the village of 

 Smyrna, Chenango co. The formation is regarded as constituting 

 the basal element in the New York Upper Devonic, for though its 

 species are largely those of the fauna beneath yet there are new ap- 

 pearances which give to it the distinctive stamp of later age. On 

 this quadrangle the formation in Carr's quarry, 2 l / 2 miles west of 

 Tully is 23 feet, 4 inches thick, in 10 layers, varying from 1 foot, 

 3 inches to 3 feet, 9 inches in thickness. The principal part of the 

 rock is fine grained blue black limestone that weathers light gray, 

 very hard when fresh but after long exposure inclined to crum- 

 ble into a mass of small angular fragments. The basal layer and 

 others higher in the section are shaly to a greater or less degree. In 

 its more western exposures the limestone is purer and the layers 

 thicker. 



The best exposures afforded on this quadrangle arc in the Buck- 

 tail ravine above Spafford valley and i l / 2 miles east on the east side 

 of the Otisco valley; also in the highway over Kingslev hill, i l / 2 

 miles west of Maple Grove and on Bear mountain mile southeast 

 of Maple Grove. This limestone is seen in the ravine 1 mile south- 

 east of Vesper and in the escarpment near the highway from that 

 point for ij/ 2 miles, including Carr's quarry. It is exposed in the 

 highway leading east up the hill on the south side of the ravine on 

 the east side of the valley y/ 2 miles south of Tully ; also in the high- 

 way and in Ousby's quarry 1 mile southeast of Tully ; in the ravine 

 1 mile northeast of Tully ; at Tinkers falls ; in the highway on the 

 north side of Shackham brook and 3 miles farther north in the same 

 valley ; near the top of the hill 1 mile southeast from Berwyn and 

 at the top of the hill iy 2 miles from that point toward the southeast; 

 and there are several small exposures along the northern face of 

 South mountain and the hill east of Tully. 



