94 
COAL MEASURES. 
Coal Measures of North America* 
In this country the carboniferous series of rocks 
is extensively developed, as v^ill be seen in the 
second part of our Treatise, in v^^hich 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 different geological 
eras ; the jnost 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 argilla- 
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 
England. — New Red Sandstone.— Oolite.— Green Sand. — 
Chaik.-Flints. 
The upper secondary rocks, which we have sta- 
ted lie above the coal measures, comprise, 1. The 
New Red Sandstone ; 2. Oolitic Rocks ; 3. Green Sand; 
