770 JESSE E. HYDE 



column as the Pocono sandstone formation of the Appalachians 

 and are generally regarded as its approximate equivalent. The 

 Pocono sandstone is exposed in various belts in the Appalachians 

 from the anthracite fields southwestward through central Pennsyl- 

 vania, the western part of Maryland, and on both sides of the bound- 

 ary line between Virginia and West Virginia to a point in Virginia 

 south of the southern part of the last-named state. 



The following paragraph is presented as a brief summary of 

 the published accounts of the Pocono in this region and of a new 

 interpretation of the members forming it; it appears that the irregu- 

 larity in thickness and composition of the Pocono at various points 

 in northeastern West Virginia can be understood on the theory 

 that there was there erosion of its beds to the extent of i,ioo or 

 1,200 feet prior to the laying down of the Greenbrier limestone. 



It appears that the Pocono in northern Virginia, western Mary- 

 land, and south-central Pennsylvania consists of four members 

 (a fifth higher member has been reported from a single locality), of 

 which the second one in ascending order is a prominent gray or white 

 conglomeratic sandstone, the Purslane sandstone.^ It appears that 

 this sandstone-conglomerate member is the one which comprises 

 almost the whole of the so-called Pocono in its thinned more 

 westerly outcrops along the line between Virginia and West Vir- 

 ginia and in West Virginia, and that there the underlying member 

 has heretofore generally been included with the Catskill.^ In 

 western and southwestern Virginia, three members have long been 

 recognized^ which, it appears, correspond very closely to the upper- 

 most three in northern Virginia (excluding the seldom-observed 

 highest member), and the massive conglomerate sandstone at the 

 base in southwestern and western Virginia corresponds exactly with 

 the second member or Purslane sandstone to the northward. It 

 further appears that there is beneath this sandstone in western 

 and southwestern Virginia a member, closely corresponding to the 

 lowest member or Rockwell to the northward, which has been 



^ G. W. Stose, Pawpaw-Hancock Folio, No. 179, U.S.G.S., 1912. 



^ Piedmont, Accident-Grantsville, Franklin, Staunton, Monterey, Buchannon 

 Folios, U.S.G.S. 



3 W. M. Fontaine, Am. Jour. Sci., 3d ser., XIII (1877), 115-16; J. J. Stevenson, 

 Bull. Geol. Soc. Am., XIV (1903), 29, and citations there given. 



