REPORT OF THE STATE PALEONTOLOGIST 1902 971 



the Cuba sandstone. They seem to be of local development 



and even in this region are scarcely worth mentioning. At a 



number of horizons the shales become locally calcareous and 



a bed G, 8, or even 10 inches thick may pass into a very impure 



limestone that where exposed on the surface has usually been 



leached out into a honeycombed mass of brachiopod casts and 



molds. These thin beds weather into! soft rusty blocks or 



chunks that are often very conspicuous on the surface. In 



many places the sandy shales and thin shaly sandstones, 



specially near the top of the Chemung, are stained bluish black 



by manganese. Ripple markings are common at various 



horizons and in a few places what may possibly be obscure mud 



cracks are found. Minute mica scales often fleck the parting 



planes of the thin shaly argillaceous sandstones. As a rule 



the Chemung strata are abundantly fossiliferous. Brachiopods 



and lamellibranchs are the most abundant forms while in some 



of the abandoned quarries above mentioned sponges are also 



to be found. 



Cattaraugus beds 



Wolf creek conglomerate lentil. A marked change in the con- 

 ditions of sedimentation caused the deposition of a conglom- 

 erate that is most prominently developed on Wolf creek and 

 is known as the Wolf creek conglomerate. Its pebbles are 

 predominantly flat or discoidal and hence it is also often called 

 the " flat pebble " conglomerate in contradistinction to the 

 Glean or "round pebble" conglomerate occurring higher in the 

 series. The pebbles are mostly of vein quartz though a few 

 are of red jasper. They vary in size from an inch or two in 

 diameter down to ones of coffee or wheat grain size. Pebbles 

 of the larger size are not abundant. The average size is per- 

 haps less than a half inch in diameter. The mass of the rock 

 is as a rule a coarse, loosely cemented, cross bedded sand 

 sometimes bleached white but usually stained yellow or brown 

 by iron. In some places on Wolf creek it becomes locally 

 massive, and projects from the valley walls in ledges 15 to 20 

 feet high from which large blocks are shed into the valley 

 below. One of the most prominent characteristics of this 

 conglomerate is its rapid variation in thickness. Nowhere more 

 than about 20 feet thick, it often in a few hundred vards thins 



