GEOLOGY OF LAKE PLEASANT QUADRANGLE 4I 



very fossiliferoiis black shale with strike north 40° east and dip 

 10° west (see plate 8). Considering the angle of slope on which 

 the shale outcrops as 5°, a distance of 1300 feet, and an average 

 dip of 7°, a thickness of about 275 feet of shale lies along the brook 

 between the Black River-Trenton limestone belt and the synclinal 

 axis. 



The only other shale outcrop occurs in the north bank of the 

 creek which comes down from the north side of Mount Dunham and 

 only a few rods below the quarry and Lowville section above de- 

 scribed. This shale is hard and limey, with strike east-west, dip 

 20°, and it must lie practically at the base of the Canajoharie. 



Doctor Ruedemann has kindly determined the following fossils 

 from shale specimens collected by the writer : Diplograptus 

 amplexicaulis, Climacograptus putillus, Lin- 

 gula curt a, Rafinesquina alternata (small), D a 1- 

 manella testudinaria, Plectambonites sericeus 

 (small), Glossina trentonensis, Orthoceras hud- 

 sonicum, Primitiella unicornis and Calymmene 

 s e n a r i a. 



Concealed Cambro-Ordovicic strata. A considerable area 

 (specially colored on the map) of the Paleozoic strata is concealed 

 under Pleistocene deposits, but judging by the distribution, thick- 

 ness, and structural relations of the various known formations, we 

 may be practically certain that all this area, except toward the north 

 end, consists of Cambric strata. 



Between the north base of West hill and the limestone belt, the 

 Potsdam, Theresa and Little Falls formations must lie in regular 

 order with northward dip. From the limestone-shale areas eastward 

 the Little Falls dolomite, with westward dip, must extend almost, 

 if not quite, to the minor fault through the village. 



The complete failure of outcrops in the northern portion of the 

 outlier causes uncertainty regarding the distribution of the forma- 

 tions there, though the Ordovicic limestones and shale quite certainly 

 reach farther northward than shown on the map. 



The Outlier near Hope 

 General statements. This interesting outlier, here described for 

 the first time, occupies the Sacandaga valley bottom between i and 

 ^ miles northeast of Hope post office. It is barely possible that 

 Emmons noted the occurrence of Little Falls dolomite here in his 

 study of the " Geology of the Second District." In the quotation 



