196 



Report of the State Geologist. 



For a distance of about ten miles southward along the lake shore from 

 Aurora, the escarpment is composed of the soft, bluish clayey shales of the 

 Hamilton group, the lines of bedding showing a distinct but rather undula- 

 tory southward dip. 



In the vicinity of King's Ferry the upper part of the ravines expose the 

 Tolly limestone about 15 feet thick and 200 feet above the lake. It gradually 

 approaches the shore and becomes the cap-stone of the escarpment near Lake 

 Ridge. It is continuously exposed southward in the face of the bluff showing 

 several low undulations. In the vicinity of Taughannock the lower layer 

 reaches the level of the lake and is partially submerged. Approaching Lud- 

 lowville the limestone rises to the top of the escarpment on the north side of 

 the Salmon creek opening. On the south side of this break in the escarp- 

 ment it again appears high up on the bluff, descending rapidly toward the 

 south and disappearing beneath the waters of the lake two and half miles 

 from the head. 



The extensive anticlinical flexure indicated by the position of the Tully 

 limestone as above set forth is referred to by Professor Hall in the report on 

 the Fourth District and by Mr. Vanuxem in the report on the Third Dis 

 trict. Its position and dimensions as it appears on both sides of the lake are 

 more particularly described by Prof. S. G. Williams of Cornell University in 

 the Sixth Annual Report of the State Geologist, page 22. 



Professor Williams says that the flexure carries the limestone to the 

 height of 230 feet above the lake at Norton's landing and that on the west 

 side of the lake the limestone is submerged on the north side of the flexure, 

 rising above the water between Trumansburg landing and Taughannock and 

 forming an arch 160 feet high and nearly four and a half miles span, passes 

 beneath the water again about three and a half miles north of the head of 

 the lake. 



A fold of this magnitude must affect the strata to a great depth, far 

 below the salt bed. 



In the Ithaca test well, the Tully limestone was reached at the depth of 

 440 feet , below the mouth of the well, or 422 feet below the lake level. 

 Adding the height of the arch at Norton's landing, 230 feet, gives an eleva- 

 tion of the strata of 422 feet + 280 feet = 652 feet. 



The unusual thickness ascribed to the Hamilton group in the Ithaca well 

 shows its great increase tow ard the south. Data from which to ascertain 

 the exact difference in the thickness of these shales at Ithaca and at the mouth 

 of Salmon creek are not at hand, but it is probably more than a hundred feet. 



