98 Report of the State Geologist. 



The thickness of the formation in the well at Ithaca, as given 

 by Ashburner and Frosser, is 100 feet. Along Seneca lake there 

 is opportunity to allow a larger figure, but owing to the difficulty 

 of determining dip in this rock its precise thickness remains a 

 matter of conjecture. In the creek at Highland Landing, the 

 entire height of the bank (about 120 feet) is exposed in one spot 

 by a road descending into the ravine ; the entire section here is 

 within the Genesee. Addition must be made to a moderate but 

 uncertain extent, corresponding with exposures in the bed of the 

 brook for a furlong or more, down to a cascade formed by the 

 Tully limestone. 



The exposures in Lodi glen present the same difficulty as 

 regards dip. The Tully limestone dips between JST. and JST. W. 

 for the great part of its exposure, and the Genesee a little 

 west of ( D) the main fall, dips in the same direction for a short 

 distance, but the reverse may be true in the interval C-D. The 

 data of elevation were obtained as follows : 



A-B, 20 feet, hand-level, somewhat uncertain. . 



B-C, 50, the same, more reliable. 



C-D, 90, three aneroid observations agreeing closely. 



Height of falls, 125, Gibson's map. Includes 7 feet of Genesee. 



Chasm above falls, from rails on bridge, 60, aneroid repeated. 

 Total, 338. 



Elevation of track at station close by, 785 A. T. Seneca lake, 

 441 ; track above lake, 311 ; error, 6. 



The lake side exposures are poor on Cayuga lake. Those on 

 Seneca lake (fig. 2*3) begin one and one-half miles south of Lodi 

 Point and disappear under the Portage beds at Faucett's Point, 

 a short distance north of the county line. They do not define 

 the thickness. 



In the " Higher Devonian Faunas of Ontario County, ]S"ew 

 York," by J. M. Clarke, a peculiar layer is described as occupy- 

 ing a position near the middle of the Genesee shale from. 

 Canandaigua lake westward. This layer consists of a hard lime- 

 stone, more or less schistose, a foot in thickness, composed 

 almost entirely of shells of Styliola fissurella, and hence named 

 the Styliola limestone. Search was made for this rock along the 

 Seneca lake exposures, but without success. The exposure of 



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