GEOLOGY OF THE PENN YAN-HAMMONDSPORT QUADRANGLES 5 1 



High Point sandstone 



In structure and appearance the formation designated the High 

 Point sandstone is on these quadrangles a repetition of the Grimes 

 sandstone on a slightly enlarged scale. It is an arenaceous band 

 about 100 feet thick, in which the sandy layers are from 1 inch to 

 3 or 4 feet thick and the separating shales have the same range as to 

 thickness and vary from light blue to black. The sandstones are 

 somewhat lighter colored than those below and weather to a 

 light gray except some calcareous layers that become rotten and 

 rusty on exposure. 



The proportion of sandstone increases toward the west to the Gen- 

 esee river where the formation is 185 feet thick and the proportion 

 of shale is very slight. In the Genesee river section and westward 

 to Lake Erie where it has gradually diminished to a few feet in thick- 

 ness it is almost barren of fossils and no brachiopods have been 

 found in it. 



At Naples, the typical exposure, the sandstones project from 

 near the top of the formidable cliff at High Point and include a large 

 calcareous lens composed of Chemung brachiopods and crinoids. 

 The formation has been traced from Naples eastward and across 

 these quadrangles to the vicinity of Elmira where lenses of similar 

 character and appearance to the one at High Point are of frequent 

 occurrence in it. The fossil contents of these lenses are exceedingly 

 variable, no two of them being composed of the same species. 



The High Point sandstones are exposed in a small ravine i\ miles 

 northeast of Italy Hill and a calcareous lens outcrops three quarters 

 of a mile north of that village. Small outcrops and a thin lens occur 

 near the east and west road over the hill 2 miles north of Ham-- 

 mondsport. The sandstones outcrop at North Urbana and at 

 Wayne Four Corners, also in a ravine and along the roadside 2 

 miles north of Sonora; near the mouth of the ravine 1 mile east 

 of Savona and along a small stream that flows into Mead creek 

 1 mile north of Monterey. 



They are exposed in the quarries on East hill at Elmira and show 

 an extensive calcareous lens. • 



West of the Genesee river they outcrop near Rock Glen in the 

 Oatka valley and in Chautauqua county at Forestville, Laona and 

 Brocton. The horizon, with the sandstones almost entirely elimi- 

 nated, dips under the water of Lake Erie 3 miles north of the State 

 line. Fossils are not very abundant on these quadrangles^except 

 in the calcareous masses. 



