GEOLOGY OF THE HONEOYE-WAYLAND QUADRANGLES 19 



CASHAQUA SHALE 



The black shales are succeeded by nearly 200 feet of light col- 

 ored bluish gray or olive shale, in which thin flags occur occa- 

 sionally, and a few thin layers of black shale are interstratified. 

 Calcareous concretions, and thin concretionary layers, continuous 

 for but a short distance, are common in the higher portion of the 

 formation. 



Occupying a position between two heavy beds of black shale 

 it is easily recognized by its lighter color and peculiar structure, 

 wherever it is exposed, from Seneca lake to Lake Erie, and its 

 peculiar and interesting fauna has made it the subject of careful 

 study, the results of which, with a list of its fossils, may be found 

 in State Museum Bulletin 63 and Memoir 6. 



The Cashaqua beds are abundantly displayed in a very large 

 number of ravines on these quadrangles. Among the more favor- 

 able and accessible exposures are the upper beds of Whetstone 

 creek two miles west of Honeoye and the lower along the road 

 half a mile southeast of Hemlock ; along Canadice outlet above the 

 Glenville mills; in Shurger's glen two and one-half miles west of 

 Hemlock; in all of the large ravines on both sides of Conesus 

 lake, and the upper beds at the mouth of the two large ravines on 

 the east side of the valley half a mile south of the head of the lake. 



RHINESTREET BLACK SHALE 



The band of black shale that succeeds the Cashaqua shale and 

 has a thickness on these quadrangles of 30 to 40 feet, was formerly 

 known as the " upper black band." It was designated as above in 

 State Museum Bulletin 63, from its exposure at the locality in the 

 Canandaigua lake valley known as Rhinestreet, where it is 22 to 

 25 feet thick. It increases rapidly toward the west and on Lake 

 Erie is 150 to 185 feet thick. 



It is a well-defined band of slaty, bituminous black shale between 

 formations of much lighter color, and, having greater power of 

 resistance to erosive forces than those beds, it frequently produces 

 cascades in the ravines along the line of outcrop. 



It appears at most of the exposures of the upper Cashaqua 

 beds in these quadrangles. It is seen to great advantage in the 

 walls of the amphitheatre in the ravine of Whetstone creek half a 

 mile south of the Honeoye-Hemlock road. It is also well exposed 

 in Shurger's gully two and one-half miles west of Hemlock ; in the 

 two ravines half a mile south of the head of Conesus lake, east 



