LOWER SECONDARY ROCKS. 



237 



The Catskill Mountains, from the base to near the 

 loftiest summits, are composed of strata of this sand- 

 stone, through a thickness of 3000 feet or more 



CHAPTER XXII. 

 GEOLOGY OF THE UNITED STATES. 



LOWER SECONDARY FORMATIONS. 



Carboniferous Group (De la Beche). Medial O^der, 



Secondary Rocks — Their Division. — Carboniferous Limestone 

 — Its Range. — Mr. Featherstonhaugh's Account of it. — The 

 Coal Measures — Of what they Consist — Their Situation. — 

 Anthracite Coal Measures — Prof. Rogers's Account of them. — 

 The Shales. — Section of Coal Measures of Pennsylvania. — 

 Section of Carboniferous System of Ohio. — Coal Measures 

 on Kenawha River — At Wheeling, Va. — At Pittsburgh — At 

 Kiskiminitas. — Millstone Grit and Shale. — May we expect to 

 find Coal in New-York 1 



Having " worked our passage" through the con- 

 torted strata of the transition series, we are now 

 prepared to launch out upon the great secondary 

 formation, where, if we mistake not, we shall find 

 smoother sailing. 



The lower secondary rocks consist of three series : 



1. Carboniferous Limestone. 



2. The Coal Measures. 



3. Millstone Grit and Shale. 



Carboniferous Limestone. — Bearing in mind, then, 

 that we are working our way upward, from granite, 

 the lowermost rock, to the surface, we next come 

 to the carboniferous limestone, resting upon the 

 old red sandstone* just described. 



* At Lewiston, ten miles below the Falls of Niagara, we can 

 see the old red sandstone immediately under the great carbon- 

 iferous limestone formation. 



