390 The Upper Devoxian Deposits of Maryland 



with numerous quite large blocks of rock varying in texture from a 

 coarse sandstone to a conglomerate. Some of the sandstone blocks contain 

 layers of pebbles and the others vai-y from those in which part of the 

 pebbles are more than an inch in diameter to a conglomerate composed of 

 small ones. The pebbles, which are largely white quartz, somewhat len- 

 ticular in shape, break with a smooth fracture on the joint surfaces. It is 

 evident from the presence of these numerous and large blocks that this 

 ridge was formerly capped by this conglomerate and sandstone. The soil 

 by the roadside up tlie ridge contains large numbers of white quartz 

 pebbles which have been derived from the decomposition of this rock. In 

 appearance this conglomerate considerably resembles the one described on 

 Pea Ridge in the northern part of Garrett County at Mr. John Robinson's 

 and, to some extent, the fiat pebbled conglomerates in the Chemung of 

 southwestern ISTew York. To the west of tlie road is a considerably higher 

 point on the slope of which are quite large blocks of sandstone containing 

 numerous specimens of a few species of Chemung fossils : Atrt/pa hystrix 

 Hall and Douvillina cayuta Hall are especially abundant but other 

 species are associated with. them. The conglomerate and sandstones are 

 on the western side of the anticlinal axis where the dip is westerly and as 

 the fossiliferous sandstones are on the ridge to the west of and higher 

 than the conglomerate there is no question but that they occur at a 

 stratigraphically higher position than it. The fauna of the sandstones is 

 very similar to that foiuid at several localities in the vicinity of Deer 

 Park and mostly on the eastern side of the anticlinal axis. 



Directly above the four corners along the side of the Altamont Road 

 to the north of Deer Park are exposures of olive shales alternating with 

 thin layers of calcareous sandstones containing fossils. In some of these 

 layers specimens of Ambocoelia umbonata (Conrad) are very abundant 

 forming a large part of the rock. There are other layers which contain 

 specimens of Leptostrophia perplana (Conrad), var. nervosa Hall, Cho- 

 netes scitulus Hall and Atrypa hystrix Hall. Near the top of the hill are 

 numerous blocks filled with specimens of Leptostrophia perplana 

 var. nervosa Hall indicating that they are, apparently, above the 

 zone in which Ambocoelia umbonata (Conrad) occurs so abundantly. 



