1210 



NEW YORK STATE MUSEUM 



Wilbur limestone, and in the limestone have been found 

 rounded waterworn boulders of sandstone incrusted with fossil 

 bryozoans and corals. 



Farther to the northward, at the Hill quarry, the old land 

 surface of the sandstone is quite smooth, but still farther north, 

 in the incline into the North quarry just west of the engine 

 house (E on map, pi. 2), the same surface is again as rough as 

 at the first locality. 



The unconformity is expressed not alone by the eroded sur- 

 face of the Champlainic sandstones, but also by the discordant 

 strikes and dips of the involved formations, which lie at nearly 

 right angles to each other. At the locality U the sandstone 

 strikes n. 10° w. (true meridian) with an easterly dip of 60°; and 

 the Wilbur limestone strikes n. 55° e. ; dip 30° n. w. This general 

 attitude of the two formations is maintained at all points 

 where the unconformity has been measured, though there 

 is some variation in the relationship, which can be ex- 

 plained by supposing the dip and strike of the sandstone to 

 have been somewhat variable when the region was submerged 

 beneath the Siluric waters of the Wilbur sea. At the angle of 

 Union street, just south of locality U, the sandstone strikes 

 n. 21° w., dip 60° e. On the old tram track below the Middle 

 quarry, the sandstone strikes n. 24° w., dip 70° e. ; and the Wilbur 

 in the hill above strikes n. 49° e., dip 75° w. At the entrance to 

 the Hill quarry, which is an excellent place to examine the un- 

 conformity, the sandstone strikes n. 44° w., dip 50° n.e. ; and the 

 limestone strikes n. 41° e., dip 75° n. w. On the incline in the 

 North quarry, which is just west of the engine house (marked 

 E on map, pi. 2), the sandstone strikes n. 4° to 6° w., dip 70° e. ; 

 and the limestone strikes n. 71° e., dip 10° w. 



The nonconformity represents a period of land conditions in 

 this vicinity which continued through the epochs of deposition 

 of the Shawangunk grit, the Medina sandstone, the Clin too lime- 

 stone and shale, and the Rochester shale and possibly the Lock- 

 port limestone. All of these formations, absent from the Ron- 

 dout section, were laid down farther to the westward and south- 

 ward, as described by Hartnagel in his paper on the Cobleskill 

 limestone. 



