CANANDAIGUA AND NAPLES QUADRANGLES 33 



the western. This tendency to increase westward is manifested 

 beyond the area of the map, for we find the bed to be continuous 

 from here to Lake Erie, where its thickness is more than 200 feet. 

 It may be traced eastward to Seneca lake, where its thickness is 

 but 1 foot. 



The rock is essentially devoid of organic remains with the excep- 

 tion of fragments of plants, specimens of Spathiocaris, teeth 

 of Oonodonts and a few small Lingulas. These rocks are to be 

 seen in Italy hollow in the ravine already referred to near the Big 

 Tree schoolhouse, in the Naples valley at the foot of Hatch hill 

 near the salt well, on both sides of the Naples and Middlesex val- 

 leys to Middlesex Center, and on the north side of Genundewa. The 

 formation takes its name from the exposure on the road running 

 from Naples to Seaman hill, on the west side, which is known 

 locally as Rhinestreet and along which there are constant expo- 

 sures of this formation. They may be seen also in the upper part 

 of all the large ravines on the west side of Canandaigua lake to 

 the iron bridge over the Foster gully, 2 miles south of Cheshire ; 

 in the Bristol valley in the ravines on both sides as far north as 

 Bristol Center and about ^ mile north of Boswells Comers; in the 

 Honeoye valley in all the ravines between the Hancock farm and 



the foot of the lake. 



Hatch shale and flags 



Blue and olive shales with frequent thin layers of black shale 

 and thin sandstones. The sandstones become more frequent 

 and thicker in the upper part of the formation ; the lower layers 

 carry very symmetric calcareous concretions from 2 inches to 2 

 feet in diameter. This mass immediately overlying the Rhine- 

 street black shales, or the second Mack hand of some of our 

 reports, attains a thickness of 290 feet and its resistant char- 

 acter, due to the presence of many layers of hard sand- 

 stone and flags, is the fundamental cause of the highlands on 

 the Naples quadrangle. These beds are equivalent in part to 

 the Gardeau beds of Hall in the Genesee valley section, but 

 there are reasons for not applying the latter term in the Naples 

 meridian as it can not be employed with exactitude. 



