Luther — P< >rtag e Sam >st< >x es. 



285 



The exposure of the Portage sandstones in the walls of the deep gorge () f 

 the Genesee river, near the high bridge of the Erie railroad, is by far the most 

 extensive and best known. The thickness of the individual layers and the 

 aggregate thickness of the sandstones appear to be greater here than elsewhere. 

 < )n the west side of the river, a short distance below the village of Portage 

 ville, a bed of sandstones, nearly all of which are compact, is separated by 

 six feet of shales from a similar bed about thirty-five feet thick, beneath 

 which the concretion bearing shales are exposed with a thickness of eight feet. 

 The upper bed of sandstones was extensively quarried during the construc- 

 tion of the Genesee Valley canal for material for locks, culverts and the great 

 aqueduct that crossed the river at this point. 



Above Portageville the fall in the river is very slight, and the horizon of 

 the upper sandstones is above the river bed for several miles to the south. 



The Genesee Blue Stone Co. has a large quarry in these upper beds, 

 about three miles south of Portageville, near the tracks of the Western New 

 York and Pennsylvania railroad, the product of which is used in Rochester 

 and New York city. 



The next good exposure westward is in the gorge of Wolf creek, one half 

 mile below the village of Castile. A band of black shales is exposed near 

 Hopkins & Son's mill, and the sandstones are below it. The top of the 

 sandstones is here 150 to 200 feet lower than the crest of the ridge between 

 the Genesee river and the Silver lake basin, and the line of outcrops is carried 

 northward by the configuration of the land, and crosses the ridge about three 

 miles north of Castile. It bends southward around the Silver lake basin, and 

 again to the north over the high lands between the lake and the Oatka Creek 

 valley. 



The extensive quarries of the Warsaw Blue Stone Co., at Rock Glen, 

 expose about thirty-five feet of these sandstones. As a stratum of the concre- 

 tionary shale is exposed in the bottom of the quarry, it is probable that the 

 layers utilized are those of the middle and lower beds. 



From the records of the salt w ells in the southern part of the Warsaw 

 valley, it appears that the totcil thickness of the Portage rocks is here 800 to 850 

 feet, or about 200 feet greater than in the Naples section, thirty-five miles east. 



The high plateau in the western part of Wyoming county, betw een the 

 Oatka Creek valley and the valley of Tonawanda creek is covered by drift, 

 and the bed rock is rarely exposed. 



The large ravine near Yarysburg presents a fine section of the shales of 

 the middle Portage that reaches the lower part of the sandstones, thereby 



