GEOLOGY OF THE WATKlNS AN D ELMIRA QUADRANGLES 17 



Genesee river to the west side of the Naples valley where the harder 

 layers project at the top of the cliffs at the south end of High Point. 

 While the original description of the Portage sandstones on the 

 Genesee river by James Hall, in his report on the geology of the 

 fourth district, would apply except as to thickness, to most of the 

 layers of the sandstone here represented, there are essential differ- 

 ences. Not only are the individual layers and the whole formation 

 thinner and softer but an extensive calcareous lens in the middle of 

 the section at Naples contains 23 species of brachiopods and 9 other 

 organisms, none of which belong to the normal Naples fauna but are 

 of distinctively later date. These lists have been given in various pub- 

 lications more specially in United States Geological Survey bulletin 

 16 and State Museum bulletin 63. Toward the east the formation be- 

 comes still softer and more unlike the typical section, but as the same 

 changes take place in the adjacent beds above and below, it still ap- 

 pears as an arenaceous band composed of thin layers of sandstone 

 separated by hard blue shale. On these quadrangles some of the 

 sandstones are from 1 to 2 feet thick, compact and durable, with the 

 characteristic light bluish gray color of the Portage sandstones and 

 are quarried extensively in the vicinity of Elmira. At the bottom 

 the change from the thin flags and soft shales of the West Hill beds 

 is quite well defined but it is more gradual at the top. The forma- 

 tion, as here limited, includes the strata up to a horizon where soft 

 blocky shales containing many brachiopods appear. 



The rock is exposed on the hill east of Elmira at 11 50 to 1200 feet 

 A. T. and in the cliffs and quarries on the south side of the Chemung 

 river west of Elmira at 1150 to 1200 feet A. T. ; in the quarries at the 

 mouth of the Latta brook ravine 920 to 950 feet A. T. and the 

 A^oight quarry ^ mile farther south at 940 feet A. T. ; in the old 

 quarry southwest of the station at North Elmira, 930 feet A. T. ; in 

 the Doane quarry 1 mile east of Horseheads and another Y± mile 

 north at 950 feet A. T. ; in the quarry near the highway 2 miles north 

 of Horseheads, 950 feet A. T. and two hillside quarries lj4 miles 

 south of Pine Valley, 1080 to 1160 feet A. T. and in a small ravine 

 1 mile west of Sullivanville, 1120 to 1200 feet A. T. Calcareous 

 lenses are exposed in the East hill quarries at Elmira at 1060 feet 



