284 THE CAMBRIAN. [wjll.81, 



fauna. 1 It includes Lingulepis acuminata. Obelella prima, Ptyclioparia. 

 calcifera, aud P. saratogensis, species identical with those found at the 

 upper horizon of the Potsdam in association with Dikelocephalus of 

 Saratoga County, New York. Subsequently he discovered in the lime- 

 stone above the quartzite, at the south end of Stissing Mountain, fossils 

 that indicated the Middle Cambrian or Paradoxides zone. The species 

 are Eyolithes billing si ?, Leper ditia ebenina, Kutorgina stissingensis, and 

 Olenoides sti&singemis. 



The stratigraphic succession is more or less interrupted by faults and 

 the rocks are masked by the drift deposits. The succession as deter- 

 mined by the known stratigraphy, and the fauna is, first, at the base a 

 massive bedded quartzite, resting upon the gneiss below, and subjacent 

 to a bed of hard, compact limestone. In the quartzite the Olenellus 

 fauna has been found, and in the bed of limestone immediately super- 

 jacent to it one of the characteristic fossils of the Lower Cambrian 

 fauna, HyolitheUus micans occurs. In the superjacent limestone, the 

 thickness of which could not well be determined but wbich appears 

 to be considerable, the Middle Cambrian fauna was found in an are- 

 naceous limestone, passing frequently into a calcareous shale ; and in 

 the vicinity of Poughkeepsie the Upper Cambrian fauna occurs in a 

 somewhat similar limestone. 



The contrast of the sedimentation of this section with that of Wash- 

 ington County is very striking. In the latter, the quartzite of Stissing 

 Mountain is represented by the great thickness of shales, and iuter- 

 bedded limestones, slates, and sandstones; and the limestone of the 

 Middle and Upper Cambrian of the Dutchess County section are entirely 

 replaced by slates, schists, and sandstones, both in Rensselaer and 

 Washington Counties. This difference in sedimentation is shown all 

 along the northern Appalachian Province from Dutchess County to the 

 Canadian border, and on to Quebec aud down the St. Lawrence River 

 to Cape Rosier. It represents the accumulation of sediments in a grad- 

 ually sinking area and in a relatively shallow sea. It is a curious fact 

 that near the old shore line the basal sandstone, "Granular Quartz" 

 of the Lower Cambrian is almost directly succeeded by the massive 

 limestones of the " Marble n belt. Unless there is here an area of non- 

 deposition, the lower portion of the limestones of Berkshire County, 

 Massachusetts, Rutland and Addison Counties, Vermont, represent the 

 sedimentation of Middle and Lower Cambrian time. 



The preceding paragraph was written several months prior to the 

 discovery of Cambrian fossils in the limestones of the East Rutland 

 Valley by Dr. Wolff, in 1890. 



'Discovery of fossiliferous Potsdam strata at Poughkeepsie, N. Y. Am. Assoc. Proc, vol. 34,1886, 

 pp. 204-209. 



2 .Recent explorations on the Wappinger Valley limestone of Dutehoss County, New York , No. 5 

 discovery of fossiliferous Potsdam strata at Poughkeepsie, N. Y. Am. Jour. Sci., 3d aer., vol. 31, 

 1886, pp. 125-133. Vassar Bro. Inst., Trans., vol. 4, 1887, pp. 130-141. 



