GEOLOGY AND PALEONTOLOGY OF THE SCHOHARIE VALLEY 129 



deposition the shore was abruptly advanced over the eroded 

 sandstone ledges which formed the shore and supplied detrital 

 material, to the newly uncovered limestone ledges [sec fig. 

 31 A-B]. 



That there probably Avas a sudden deepening of the water and 

 a consequent sudden advance of the shore seems to be indicated 

 by the abrupt change from quartz sandroek to lime mudrock 

 which we see in the sections of the cement region southeast from 



Fig. 31 A-B Diagrams explaining the sudden change from coarse silicious to fine cal- 

 careous sediment owing to sudden advance of the sea 



Schoharie. That there was an interval of elevation into dry 

 land, accompanied by erosion, between the deposition of the 

 Binnewater sandstones and that of the Rosendale cement bed, can 

 not be held, on account of the total absence of erosion of the sand- 

 stones in any of the sections exposed. The bed preceding the 

 cement is uniformly the same in all sections, but has the aspect 

 of having been partially consolidated before the waterlimes were 

 deposited. Irregularities in the thickness of the cement bed are 

 due to irregularities in this floor bed, these irregularities being 



