Handbook of Paleontology 237 



gray, red and purple. The most prevailing rock is the 

 dark, greenish gray silicious shale or slate which ap- 

 pears to serve as a ground mass in which all the other 

 rocks, quartzites, red and purple shales, limestones and 

 sandstones, are distributed. These rocks show a very 

 much folded structure and are of unequal hardness. 



The Stissing limestone was named (Walcott '91) from 

 its occurrence in Stissing mountain in northern Dutch- 

 ess county. The beds overlie the Olenellus-beax'mg 

 beds. It has been suggested (Ulrich) that the some- 

 what doubtful Middle Cambrian sediments occurring 

 in Stissing mountain originally belonged farther to the 

 east and were moved westward to their present posi- 

 tion by a thrust fault. 



The Ozarkian system of rocks (figure 25) rests upon 

 the Precambrian crystallines from which it is separated 

 by an unconformity. New York State evidently was very 

 largely land during Cambrian times. The first important 

 Paleozoic submergence of the southern flanks of this area 

 came during the Ozarkian period with the Potsdam or 

 Saratogan submergence. 



The Potsdam sandstone (figure 26) is the basal mem- 

 ber of a new cycle of deposition which was continuous 

 through the Little Falls dolomite. Potsdam deposi- 

 tion started in the Champlain trough toward the north- 

 ern end and worked southward in that trough and 

 westward up the St Lawrence trough. It is believed 

 unlikely that the eastern and western lobes of this sea 

 connected across the southern part of New York be- 

 fore the closing stage of the Potsdam. The Adiron- 

 dack area which was much reduced by erosion and gen- 

 eral subsidence then became an island until just pre- 

 ceding the Little Falls dolomite stage a warping uplift 



