GEOLOGY OF THE WATKINS AND ELMIRA QUADRANGLES 25 



UNDULATIONS 



The aggregate thickness of geologic formations and parts of 

 formations represented on the map of the Watkins and Elmira quad- 

 rangles is approximately 2244 feet, of which 1443 feet is by reason 

 of the difference in elevation between the Genesee black shale ex- 

 posed at the level of Seneca lake 443 feet A. T. on the south side 

 of Fir Tree point, and the top of the hill near the south line of the 

 Elmira quadrangle in the southeast corner of the town of Southport, 

 and 801 feet is due to the southern dip of the strata between those 

 points, an average of 24^ feet a mile. 



From Fir Tree point the dip is toward the north and the average 

 southern dip from the north line of the Watkins quadrangle to the 

 south line of the Elmira quadrangle is 21 feet a mile. 



This dip, however, is not constant. The heavy sandstones exposed 

 in the quarries and ravines on the east side of the valley from Elmira 

 to Horseheads and on the west side to Pine Valley, and the thick 

 layer of similar character exposed on the west side almost continu- 

 ously from a mile north of Montour Falls to- the .north line of the 

 quadrangle, show the undulations to advantage. 



From' the southeast corner of the quadrangle the strata rise toward 

 the north at an average rate of 60 feet a mile for about 6 miles to a 

 point near the bend in the Chemung river east of Elmira. 



At the south end of the Pratt shale quarry, Elmira, the dip is 26 

 feet a mile north. In the large quarries on the hill east of Elmira it 

 varies from 150 to 200 feet a mile north. 



In the Voight quarry 2 miles farther north it is 52 feet a mile 

 north, and at the mouth of Latta brook, 43 feet a mile north. 



The bottom of the synclinal is reached not far from the latitude 

 of Horseheads, the quarry i mile north of the village, and the shale 

 quarry J^ mile farther north showing no north or south dip while 

 in the old quarry 2 miles north of Horseheads there is an elevation 

 toward the north at the rate of about 150 feet a mile, and another 

 quarry 2 miles farther north and other smaller outcrops show this 

 southern dip is continued to the vicinity of Millport. . 



From Millport to a mile north of Montour Falls the dip seems to 

 be 20 to 25 feet a mile south. . 



