110 THE CAMBRIAN. [bull. 81. 



In order, below, comes the Swan ton slates, and the Phillipsburgh or 

 Point Levis group, subjacent to which are the Georgia slates (or Ole- 

 nellus zone). The Paradoxides zone, the Upper Cambrian or Eophyton 

 sandstone of Great Bell Island, Newfoundland, and the Aspidella and 

 Arenicolites slates of St. John's, Newfoundland, are assembled under 

 the name <; St. Albans group." 



In this table, under the upper formations or " Potsdam group," there 

 are brought together the summit of the Cambrian (the Saratoga lime- 

 stone) and the base of the Cambrian (the Red saudrock of Vermont), 

 as well as the Keeseville sandstone, which is the lower portion of the 

 Upper Cambrian. In the " Swanton slates " (Trenton-Hudson terrane) 

 and in the u Phillipsburg or Point Levis group," we have the Calcif- 

 erous-Chazy zone. The Eophyton sandstoneplaced beneath the Georgia 

 slates and the Paradoxides beds is the equivalent of the Saratoga lime- 

 stone placed at the summit of the series. The Aspidella and Arenicol- 

 ites slates of St. John, Newfoundland, are of pre-Cambrian age. Thus 

 the lower or " St. Albans group " includes pre-Cambrian, Upper Cam- 

 brian, and Paradoxides zone strata. 



In an article on the Winooski or Wakefield marble of Vermont, Prof. 

 G. H. Perkins 1 described several sections of the strata containing the 

 quarries worked for marble, one of which has a thickness of 1,410 feet, 

 another 790, and another 710 feet. He found Salterella pulchella in the 

 marble beds and considered the series to be of Primordial age. 



When describing a section in the Cambrian formation of western 

 Vermont in the town of Georgia, Franklin County, Mr. C. D. Walcott 2 

 stated that the section consisted of a massive belt of limestone 1,000 

 feet in thickness subjacent to a series of argillaceous shales, at the base 

 of which the Olenellus fauna occurred. He also stated that this section 

 includes in its vertical range the sections above and below Troy, N. Y., 

 in the Hudson Ki ver Valley, and those of Newfoundland and the Straits 

 of Belle Isle. This was followed in the same year 3 by a detailed de- 

 scription of the Georgia section, and another section taken near the 

 Canadian and United States boundary in the township of Highgate. 

 At this latter locality the Red saudrock series has a thickness of 1,170 

 feet; the Georgia slates a thickness of 1,000 feet. A list of the fossils 

 occurring in the strata is given in the tabulated section. Following 

 the nomenclature proposed by Sir William Logan, the Red saudrock 

 series and the Georgia slates are referred to the Middle Cambrian sub- 

 jacent to the Potsdam sandstone of the Adirondacks, and above the 

 Paradoxides slates of New Brunswick. 4 In the same year he deter- 

 mined by paleontological evidence that the roofing slates of Granville, 



•Am. Naturalist, vol. 19, 1885, pp. 128-136. 



3 Classification of the Cambrian System of North America. , Am. Jour. Sci., 3d ser., vol. 32, 1886, p. 145. 

 'Second contribution to the studies of the Cambrian faunas of North America. TJ. S. Geol. Survey 



Bull. No. 30, 1886, pp. 13-20. 



4 Op. cit., pp. 63, 64. 



