14 



NEW YORK STATE MUSEUM 



At a distance of i\ miles directly east from Thompson's old 

 quarry the Cobleskill horizon is again exposed and between the two 

 points there is an abandoned gypsum quarry. 



From this and a similar exposure farther to the northeast, we 

 may fairly conclude that this entire area represents one which 

 is underlaid by gypsum and in every case the gypsum is exposed 

 by the removal of the Cobleskill limestone and the Bertie water- 

 lime. 



There is no good evidence to show that there are in this region 

 any outcropping strata lower than the gypsum beds. This is made 

 evident when at Cayuga village but 3 miles northwest from 

 Thompson's old plaster quarry, we find the top of the gypsum 

 but 35 or 40 feet above the level of Cayuga lake. The gypsum 

 is here much lower than at Thompson's quarry, thus showing the 

 dip to be to the northwest. At Cayuga village the Bertie water- 

 lime may be seen above the gypsum, but the Cobleskill limestone 

 is not seen. However, 4 miles farther west at Seneca Falls, gypsum 

 beds of undoubtedly the same age as those at Cayuga village are 

 visible and above them lie the Bertie waterlime and Cobleskill 

 limestone. 



From the point where the Cobleskill limestone outcrops at 

 Seneca Falls, to a point directly east, where the same limestone 

 is again seen, but on the east side of the lake, there is a rise of 

 60 feet. This shows that the dip of the rocks between these two 

 points is to the west. 



Ovid, Genoa and Phelps quadrangles. On comparison of the 

 stratigraphy in this region with that of the country westward in- 

 cluded in the Canandaigua-Naples quadrangles already reported on, 

 there are some interesting local variations in the formational units. 

 All the formations between the Skaneateles shale and the top of 

 the Genesee black shale maintain their integrity eastward to this 

 meridian without change in thickness. The Genundewa limestone 

 is exposed in typical condition in the southern part of the Phelps 

 quadrangle but on the Ovid quadrangle its horizon is occupied by a 

 band of calcareous gray shale in which there is a row of large soft 

 concretions containing the characteristic fauna of this formation. 



The West River shale becomes thinner and less clearly defined 

 toward the northeast by a gradual change to lighter color and in the 

 northern part of the Salmon Creek valley on the Genoa quadrangle 

 is so far assimilated to the Cashaqua shale as to be no longer dis- 

 tinguishable from it. 



The Standish and Middlesex black shales of the western region 

 are not recognizable on these quadrangles. The Cashaqua shale 

 has- been traced across the Ovid and Genoa regions with very little 

 change in the lower part but the upper part becomes more sandy 

 toward the east and is extensively quarried for flagging. 



