CANANDAIGUA AND NAPLES QUADRANGLES 



37 



Highpoint sandstone 



Light gray sandstones in layers from 3 inches to 4 feet in 

 thickness separated by thin beds of hard blue shale. Some of 

 the layers of the rock are compact and calcareous but the larger 

 portion is laminated and sometimes shaly. Lenticular beds of 

 impure limestone composed of crinoid stems and other fossils 

 occur at High point and other outcrops. These sandstones are 

 thinner and softer toward the east. Thickness 100 feet. These 

 beds are nowhere sufficiently exposed to admit of detailed exam- 

 ination of the entire series and the upper and lower contact, 

 but 50 to 75 feet of the formation project in the cliff at the 

 south end of High point at an elevation of 1850 to 1925 feet A. T., 

 and the talus that covers the strata at the base of the hill is 

 principally composed of fallen slabs and blocks of the sandstone. 

 In structure, texture and general appearance they differ from 

 the Grimes sandstone only in being somewhat coarser and weath- 

 ering to a lighter color but they likewise differ notably in their 

 fossil contents. Fucoides verticalis, which is not seen 

 in the lower rocks, is common throughout these beds. The most 

 striking feature of this exposure consists of an irregular stratum 

 of calcareous sandstone and conglomerate 7 feet thick where 

 thickest and thinning out gradually around both sides of the hill. 

 This is a mass of brachiopods, corals and crinoid stems cemented 

 into a hard, compact layer that resists the effects of weather and 

 at one place projects 12 feet beyond the soft sandstone beneath it. 

 Several fallen slabs of this calcareous layer 10 to 15 feet across 

 are to be seen at the foot of the escarpment and many others 

 have been broken up and utilized in the construction of fireplaces 

 in the pioneer days and later in the arches of furnaces beneath 

 steam boilers, its resistance to the disintegrating effect of heat 

 making the " High Point firestone " highly esteemed for these 

 purposes in this locality. - It has, however, now fallen into 

 disuse. This highly fossiliferous layer is about 50 feet below 

 the top of the sandstone. In it a well denned Chemung fauna 

 with Spirifer d i s j u n c t u s occurs together with species 



