SUCCESSIVE DEPOSITS IX THE APPALACHIAN REGION 



431 



in Pennsylvania. It is the "Red Me- 

 dina" of the second Penns) r lvania sur- 

 vey, though under this name was also 

 included the Longwood (Salina) shale 

 of the eastern monoclinal or Blue Moun- 

 tain-Kittatinny Mountain Ridge. An- 

 other local deposit of red rocks, the true 

 Medina, was also included here. In 

 western New York occurs a great series 

 of red shales and sandstones, which at 

 Niagara, where they underlie the white 

 Whirlpool quartzite and rest on the Os- 

 wego sandstone, have a thickness of 

 1,142 feet. These shale beds have gen- 

 erally been called Lower Medina, and 

 included with the Oswego sandstone be- 

 low and the Whirlpool sandstone, the 

 Medina sandstone and shales and the 

 upper gray or Thorold sandstone above, 

 in the Oswegian group, which was made 

 the base of the Siluric. These lower 

 shales I have recently renamed the 

 Queenston shales from their exposure at 

 Queenston on the Niagara River, and 

 have referred them to their true position 

 as the equivalent of the marine Rich- 

 mond deposits elsewhere. 46 These shales 

 and sandstones are to be regarded as the 

 westward extension of the Juniata beds 

 of Pennsylvania, and they were unques- 

 tionably derived from the Appalachian 

 region, since, as I have already shown 

 while discussing the origin of the Os- 

 wego sandstone which underlies them, 

 there is no other adequate source from 

 which such material could be supplied. 



It is now perfectly well understood 

 that the red color of a series of clastic 

 sediments of this type is due primarily 

 to peculiar climatic conditions which 



'" Science, n. *.. vol. xxvil, loos, pp. 02J-(5i.»;{ ; vol. xxlx, 1000, pp. 351-350. 



