124 INDEX TO THE STRATIGEAPHY OF NORTH AMERICA. 



overlain by an oolitic limestone, 30 feet, and a dark-gray, evenly bedded limestone 50 feet in 

 thickness. In this latter limestone the following fauna occurs: 



Cryptozoa proliferum. 

 Obolus (Lingulepis) acuminatus. 

 Platyceras minutisdimum. 

 Platyceras hoyti. 

 Metoptoma cornutiforme. 

 Metoptoma simplex. 



Billingsia saratogensis. 

 Matthevia variabilis. 

 Dikeloceplialus hartii. 

 DikeloceplialuB epeciosus. 

 Ptychoparia calcifera. 

 (A.) saratogensis. 



The Calciferous formation of the New York section rests conformably oii the Upper Cam- 

 brian limestone. 



The formations now referred to the Saratogian are as follows: 



Type. — Sandstones and limestones of the south side of the Adirondacks, Saratoga County, 

 N. Y., containing the Upper Cambrian fauna. 



Correlated. — ^Upper part of Cambrian limestones of Dutchess County, N. Y., and an unknown 

 portion of the limestones of the "marble belt" of western Vermont. 



Upper part of shales of Tennessee (Knox), State of Georgia, and Alabama (Conasauga), 

 and the lower part of the Knox dolomite. 



Upper part of the sandstones of the upper Mississippi Valley (St. Croix), Upper Cambrian 

 limestones of South Dakota, Wyoming, Montana, and Colorado. 



Upper calcareous beds of the Cambrian of northern Arizona (Tonto) and central Texas 

 (Katemcy). 



Upper Cambrian limestones and shales of Nevada (Hamburg), Idaho, and Montana (Gal- 

 latin) . 



Black shales of the upper portion of the New Brunswick and Cape Breton Island Cambrian 

 sections. 



Upper Cambrian shales and sandstones of Conception Bay, Newfoundland (Belle Isle). 



Recent contributions to the classification and interpretation of the Cambrian and 

 Lower Ordovician of the New York province have been made by Grabau/*^ and also 

 by Uh-ich and Cushing.^^^ (See p. 184.) 



The general relations of the Cambrian of the Adirondacks in eastern New York 

 and Vermont, and thence southward, were thus stated by Walcott : ^" 



The strata referred to the Cambrian, on the western side of the Sutton Mountain antichnal 

 or the belt extending southwesterly from Quebec to the Vermont boundary, consist of more 

 or less of the Sillery series, as found in the vicinity of Quebec, and, according to Drs. Selwyn 

 and Ells, of a subjacent series of hard quartzite rocks interstratified with mica schist and black 

 slate. The volcanic series, referred to the Cambrian in this region, indicates that during earlier 

 Cambrian time the volcanic products were deposited contemporaneously with the included 

 sandstones and slates, thus giving a phase of sedimentation not known elsewhere in the Cam- 

 brian of the Appalachian province. For this reason and from the fact that there is not any 

 paleontologic evidence of the age of this volcanic series, I am inclined to think that it may- 

 belong to some pre-Cambrian terrane. 



Entering the northern end of the valley, between the Green Mountains and the Adirondacks 

 a sudden change occurs in the sedimentation. At the base the Olenellus fauna ranges through 

 1,000 feet of magnesian limestone, and for 250 feet higher up in arenaceo-argillaceous shales. 

 More or less arenaceous matter is associated with the limestones, and, about 2,000 feet above a 

 great lenticular mass of limestone occurs in the argillaceous shales, in which a fauna of Upper 

 Cambrian aspect is found. At other locaHties this fauna occurs in the shales themselves and 

 in a brecciated limestone at the same relative horizon. As far as known the upper portion of the 

 Cambrian is formed of the shales. Proceeding southward and nearer the old coast line in Addi- 

 son County, Vt., the limestone series is found to graduate into the Granular quartzite or the 

 beach sand. From this point this shore deposit is traced without interruption to the Massa- 

 chusetts boundary; and then, with more or less interruption, to the Hudson River below 



