94 



COAL MEASURES. 



Coal Measures of North America. 



In this country the carboniferous series of rocks 

 is extensively developed, as will be seen in the 

 secoiid part of our Treatise, in which we shall 

 present a sketch of the geology of the United States, 

 According to Dr. Mantell and some of our best ge- 

 ologists, our coal is referable to diiferent geological 

 eras; the most ancient belonging to the transition 

 series ; the next to the European carboniferous 

 group; and the third to the brown coal, or tertiary 

 lignite. The anthracite of Pennsylvania is asso- 

 ciated with conglomerates, sandstones, and argiila^ 

 ceous slate; the conglomerate being composed of 

 quartz pebbles. In the Valley of the Connecticut, 

 Professor Hitchcock states that bituminous coal is 

 intercalated in a group of strata, which he refers to 

 the new red sandstone. Extensive deposites of 

 anthracite coal are found in Rhode Island, of which 

 Professor Silliman gives an interesting account in 

 the American Journal of Science and Arts. 



CHAPTER IX. 



UPPER SECONDARY FORMATIONS. 



Supermedial Order. {Cretaceous^ Oolitic^ and Sand' 

 stone Groups. — De la Beche.) 



Upper Secondary Rocks: how Divided.— Secondary Rocks of 

 Engtaridl. — New Red Sandstone.— Oolite. — Green Sand.— 

 Chaik.-Flints. 



The upper secondary rocks, which we have s*ta- 

 ted lie above the coal measures, comprise, 1. The 

 Neiu Eed Sandstone ; 2, Oolitic Rocks ; 3. Green Sand; 



