410 On the Carboniferous Series of North America. 



time it (the limestone) reposes upon another red sandstone 

 which Mr. Weaver considers the true old red sandstone in 

 question, I have carefully traced these upper red sandstones 

 from the State of New York until they sink under the great 

 bituminous coal-field of Pennsylvania at Blossbury. 



The carboniferous limestone appears on the west side of 

 the Alleghany mountain, accompanying the coal, in Tennessee, 

 Illinois, Kentucky, and Indiana. Its resemblance to the 

 mountain limestone of England is, I believe, admitted by all 

 European as well as American geologists. I am far from be- 

 ing certain of its presence to the eastward of the outcrop of 

 the secondary coal-field in Pennsylvania; and I doubt if in 

 York State this is the same formation which in the west is in 

 close approximation with, and even contains, coal seams. I 

 do not know which of the calcareous rocks is meant by Pro- 

 fessor Eaton, as the " limestone which supports the strata 

 containing the Pennsylvania coal." My diagrams, which have 

 been laboriously worked out, exhibit no limestone in Penn- 

 S3-Ivania, between the secondary coal series and my old red 

 sandstone group which averages a mile thick. The descrip- 

 tion, therefore, refers to the contorted and frequently highly- 

 inclined limestones, which range alternately with the upheaved 

 arenaceous rocks in front of the Alleghany mountain, along 

 an area seventy miles broad. Mr. Weaver infers (p. 117.) 

 that all the carboniferous limestone series of the north-east 

 part of Pennsylvania supports equally the bituminous se- 

 condary coal of Clearfield, Lycoming, Tioga and Bradford, 

 and the anthracitous deposits of Wyoming, Lehigh and 

 Schuylkill ; the red sandstone and shales being in this view 

 continuous or identical. 



Here, therefore, is the point of difference with the views 

 I have been led to entertain. I see that both in the acknow- 

 ledged secondary bituminous coal region, and in those of the 

 anthracite districts, the carbonaceous deposits are alike based 

 on red sandstones and red shales ; but the sections distinctly 

 show, that these are neither similar nor continuous beds, 

 either of coal or sandstones; but are of different dates, the lat- 

 ter being referrible to the transition series, the former to the 

 secondary. 



On the north-east extremity of the secondary coal-field, the 

 subjacent rocks, being much more horizontally disposed than 

 further to the south, are more obscurely developed; but all along 

 the eastern escarpments of the Alleghany the relative position 

 of the entire series seems apparent enough, when traced out 

 with ordinary caution. Mr. Weaver, however, maintains that 

 the application of the term old red sandstone, to that rock 



