Explanation of Geologic Map i. 



Tully Limestone. 



Previous maps representing the outcrop of this formation have given 

 only the northern exposures through the central portion of this region. In 

 the southern towns of Onondaga county, Tully and Fabius, the best known 

 of these outcrops are in the vicinity of the Tully lakes, and at Tinkers Falls. 

 The outcrop bends thence southward into the town of Cuyler, Cortland 

 county, along the eastern branch of the Tioughnioga river, and may be 

 traced on the west side of the Tioughnioga valley through the town of 

 Truxton and almost to the township line of Homer. On the east side of this 

 valley it extends nearly as far to the south-west, bending southeastward for a 

 short distance up the valley of Cheningo creek, where it is exposed on the 

 north side, but was not observed on the south side of this valley. An excel- 

 lent exposure at Station VIP, Tripoli brook, three-quarters of a mile north- 

 west of Cuyler village, is described more fully in the following pages. 



It is seen at several places in the town of DeRuyter, Madison county, 

 along the south slope of the same valley, passes over the watershed between 

 that and the Otselic valley, probably extending as far southward on the latter 

 as the village of Otselic, Chenango county. It is thence continued in the 

 direction of Smyrna and, as stated by Vanuxem, S. G. Williams and Prosser, 

 disappears by thinning at about one and a half miles northwest of that vil- 

 lage, in the Chenango valley. At only the station cited does the exposure 

 give a clear section of the entire formation, measuring about eighteen feet. 

 The exposures in the town of DeRuyter are of portions of the beds only. 



East of Keeney Settlement, near the north line of Cortland county, the 

 limestone bounds an outlier, extending north into Fabius, east to the Madison 

 count}- line, and south to the Tioughnioga. 



Genesee Slate. 



Tli is formation is exposed at but a few points. It was observed on 

 Tripoli brook (Station VII 2 ), where about ten feet are shown, and near De- 

 Ruyter (Station I) to a thickness of eight feet, the upper portion probably 

 being covered. Toward the east it rapidly thins out, disappearing not far 



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