286 



INDEX TO THE STRATIGRAPHY OF NORTH AMERICA. 



2. There is a greater development of the Naples fauna in the west and of the Ithaca fauna 

 in the east. 



3. The shore line was probably eastward, as indicated by the fact that there is a marked 

 development of conglomerates eastward, as at Millstone. These diminish toward the west, 

 where the lower Jennings is largely composed of argillaceous shales, as at Allegany Grove. 



The thinning of these formations southward through the Virginias may be 

 traced in general stratigraphic terms in foUos of the Gfeologic Atlas of the United 

 States by Darton '='''■ ^'' ''"■ ''^ and Campbell;''^' ^=^' i^' ^^ also in other papers by 

 Darton,^^ Campbell, ^^^ and Prosser/°° 



Devonian formations in Piedmont, FranTdin, Staunton, and Monterey quadrangles. 



<^ The measurements range south through the Piedmont, Franklin, and Staunton quadrangles from latitude 39° 

 30' to 38° and west from the Staunton to the Monterey, longitude 79°-80°, in West Virginia and Virginia. 



Two quadrangles which lie southwest of the Monterey quadrangle, between 80° 

 and 81° west and 37° 30' and 38° north, have not been surveyed. Next southwest 

 come the Pocahontas and Tazewell quadrangles (81°-82° west, 37°-37° 30' north), 

 which have been mapped by Campbell. ^^^'^^* In the interval the distinction between 

 the Jennings and Hampshire is lost, as shown in the following section from the Poca- 

 hontas and Tazewell folios : 



