Wccppinger Valley Limestone of Dutchess Co., N~. Y. 31 



immediately overlying limestone. The credit of the discoveries 

 belongs chiefly to Mr. Walcott whose long and intimate ac- 

 quaintance with the pre-Potsdam strata was of great service in 

 the search. The fossils discovered have been identified by Mr. 

 Walcott, so far as the present imperfect specimens will permit, 

 as follows : 



f Olenellus asaphoides or Thomsoni ; prob- 

 ably the former; glabellas and cheek 

 From the quartzyte : \ spines. 



I Brachiopods, probably a Triplesia and an 

 [ Obolella, sp.? 



— , ^ ,. ( Hyolithdlus micans : opercula, very 



From the limestone over- ) m j \c a ^ -u j I 



, . ,, , ■ ■< well denned : rather abundant. 



lying the quartzyte, | Qhoma gp>? 



The strata containing these fossils appear to dip away from 

 the axis of the mountain at a very low angle (from 6° to 10°). 

 But the dip of the adjoining strata increases rapidly with the 

 distance from the mountain, until it reaches the usual angle of 

 the Wappinger Yalley strata, that is, from 30° to 45° ; and with 

 the increasing dip, it also acquires the general northeast and 

 southwest strike. The Olenellus quartzyte has an estimated 

 thickness of about 160 feet ; the Olenellus limestone, of about 

 75 feet. 



Overlying the Olenellus limestone, there are about 60 feet of 

 red shale, and. over this about 300 feet of limestone which in 

 turn is surrounded by the prevalent Hudson River shales of 

 the valley. Our first impression was, that the red shale and 

 tbe overlying limestone belonged also to the Olenellus group. 

 But no evidence of this could be found in fossils. Sub- 

 sequent study of the similar superposition of strata along the 

 north edge of Fishkill Mountain convinced us that it would 

 not be safe to adopt this view in the absence of paleontological 

 evidence; since the presumption would rather be that the red 

 shales are of the Hudson River group, and the overlying lime- 

 stones a post-Potsdam rock. 



Carrying on our observations for two miles to the southwest, 

 on a line across the strike, we found the strata much faulted, 

 and the quartzyte again brought to the surface. It will require 

 a most careful and laborious search to determine the extent of 

 these newly discovered strata, and their stratigraphic relations 

 to the superior formations. 



The succession of strata in the eastern part of Dutchess 

 County (and doubtless also of the entire county), as now prob- 

 ably made complete by these facts of Stissing Mountain, is as 

 follows : 



