TULLY LIMESTONE. 165 



hundred feet above the valley, and in two contiguous ravines separated by a road. The one 

 to the north is quarried, and contains good solid stone. The hill faces the east. The Cu- 

 boidal atrypa is tolerably abundant, and affords good specimens. The shales of the Hamilton 

 group are exposed below the limestone, and the Genesee slate above it. 



The TuUy limestone appears about six miles north of De Ruyter, on the west side of 

 Delphi valley, nearly opposite Fox's tavern. It was formerly quarried and burnt for lime. 



Farther west are Tinker's falls. The water flows over this rock, and falls about fifty feet, 

 the rock projecting ten or fifteen feet beyond the shale beneath it. Its thickness is about 

 twelve feet ; the lower part is considerably intermixed with shale, the upper layers being a 

 pretty good limestone : the usual fossils are present. 



At Tully four-corners, the limestone is quarried at a short distance to the southwest of the 

 village, forming a part of the low hill at the head of the valley. The quarry is open to the 

 south, and the rock is about twelve feet in tliickness, covered merely with a thin coat of allu- 

 vion. Beneath the limestone is the Moscow shale, or upper part of the Hamilton group, 

 which is very rich in fossils, and, with the refuse limestone, is used for enclosures ; but it is 

 useless, as it separates into fragments by exposure to the weather. The hill is an insulated 

 mass, showing the former action of water between the north and south valleys ; only escaping 

 total destruction, probably from holding a neutral position. 



Mr. Willis Gaylord is of opinion that this ledge extends across the valley, and forms its bottom. 

 A pond below, having been sounded by a pole, appeared to present a solid surface. This is 

 likely to be correct ; for the broad shallow valley which extends to Cortland, favors the 

 existence of a solid resisting bottom which this limestone would give, and which its southern 

 slope would greatly aid. The rocks on the top of the limestone, being of a soft and yielding 

 nature, would be favorable to a wide excavation or broad valley such as exists. 



To the northwest of Tully, and in Otisco, it appeared at several points. The nearest 

 where it is quarried, is on the hill-side by the road which leads to Amber. It is there about 

 twenty feet thick, and about fifty feet above the road. This is the point where the maximum 

 thickness was observed. 



Along the valley of Otisco, at the head of the lake, it may be seen on both sides. It is 

 quarried on the east side at Smith's, being burnt for lime. It appears towards the top of the 

 hill, about three hundred feet above the valley, showing its regular low dip to the south. 

 The ledge is about fifteen feet thick, forming a narrow terrace capped with the Genesee slate, 

 above which we find the lower part of its succeeding mass. The characters at Smith's ledge 

 are as usual ; fossils are not numerous, but such as occur in the rock, the Cuboid atrypa, 

 Priscous atrypa, &c. 



The most northern point at which the Tully limestone appears, is at Ross's hill in the 

 northeast part of the town of Otisco, which is also the highest point of the town. It caps 

 the hill, and more of its surface is there exposed than in any of its other localities. Its layers 

 form four or five steps on the north side ; and the shale, which is beneath, is exposed in a 

 well at that end. From its vertical joints, no water is retained on its surface ; and the soil 



