﻿Bulletin 19 56 



where Eurypterus is generally most easily collected. 



Note especially the heavy brownish beds at base and the hard, 

 banded gray and blue, heavy unfossiliferous bed on top. So far 

 as our observations go, fossils are limited to the Eiuypterus bed 

 as indicated in "the section. They are besides Eurypteius, Leper- 

 ditia alta, and Stropheodonta (? Orthothetes interstriatus). In the 

 stream bed back of the old mill at Cross Roads, the middle-upper 

 part of this section may be seen, and Leperditia is of common oc- 

 currence, but Eurypterus remains are rare. (See basal part of 

 No. 5, PI. 3.) Up the stream half way to Thompson's old quarry 

 it will be observed that the hard, banded limestone described 

 above caps the Euryperus substage. The dark bands seem to in- 

 dicate the change of conditions taking place and the introduction 

 of gypsum deposition. While at the old mill just mentioned, 

 note should be made of the southward dipping limestone layers 

 in the opposite bank of the creek, for as will be seen later this 

 point has an important bearing on what follows regarding the 

 true relationship of these limestones to those above the gypsum. 

 The easternmost exposure of the Eurypterus limestone is about 

 half-way between Cross Roads and Thompson's old quarry. 

 The beds are below the exposure in the quarry and the dip is to 

 the east. 



Gypsum beds. — At Thompson's old quarry one sees the section 

 shown on PI. 3, Fig. 5 (middle portion). Skirting the southern 

 edge the Cobleskill limestone with a bed of Stromatopora appears. 

 Then below are 10 feet of grayish waterlime beds with ^Lingula, 

 Discina, and several other forms. Below are 4 feet of irregular- 

 ly bedded and banded limestone ; and still lower, 18 ft. of gyp- 

 sum extending to water level in the quarry. To what extent 

 the gypsum extends below the water level we cannot state. 

 But judging from the apparent depth of the water and the east- 

 ward dip of the Eurypterus beds just to the west, it is evident 

 that a thickness of 30 ft. would not be too great for this deposit. 

 Elsewhere, east of the Plaster Mills very extensive excavations 

 have been made in this deposit. 



The plate herewith given (PI. 4) shows an abandoned quarry 



with its characteristic pond of water. It lies half way between 



Hibiscus Pt. and the railroad track. So far as we are aware, the 



gypsum beds are unfossiliferous. 



- The thickness of these deposits is a matter of considerable un- 



