FORMATIONS OF THE SKUNNEMUNK MOUNTAIN REGION 47 



shown to be no longer applicable to the formations bearing these 

 names in eastern New York, the writer has used the terms High 

 Falls and Binnewater for Medina and Clinton respectively. 1 



The Binnewater quartzite has generally been considered as 

 ■of Clinton age. This correlation was made partly on account of 

 its similarity to some of the Clinton beds in central New York 

 and also from the fact that both it and the green Brayman shales 

 formerly supposed to be of Clinton age and which underlie the 

 Cobleskill limestone at Schoharie, contain iron pyrites. 2 The 

 reasons for regarding the Binnewater quartzites as of a later age 

 than the Clinton have been stated in previous publications. 3 ' 4 



The Binnewater quartzite is not well developed in the railroad 

 cut at Cornwall. Under the description of the Longwood red 

 shales Darton states 5 : " In this cut, which is their northern- 

 most exposure, the upper members are light colored, thin bedded 

 quartzites, which have a thickness of 12 feet, and closely resemble 

 the quartzites similarly lying between the waterlime and red 

 shales in the Rosendale cement region of Ulster county." It is 

 evident, however, that of this thickness all but 1 foot belongs to 

 the Decker Ferry formation. Above the red shales there is 

 1 foot of shaly brecciated limestone, which has the stratigraphic 

 position of the Binnewater quartzite. Immediately above this 

 brecciated layer, characteristic fossils of the Decker Ferry are 

 found, showing that the Binnewater is here represented by a 

 thickness of 1 foot. The brecciated character of this bed indi- 

 cates a local stratigraphic break which is not so clearly observed 

 in any of the other sections studied. 



In Ulster county the change from the Binnewater quartzite 

 to the Wilbur limestone (=Decker Ferry in part), or to the 

 Rosendale cement where the Wilbur is absent, is an abrupt one. 

 This change appears to be due to rapid subsidence which made 

 the shore line at a greater distance and thus the finer calcareous 

 deposits were laid down over the quartzites. The studies made 

 indicate that the Binnewater quartzite was followed closely by 

 the deposition of the overlying limestones. In this connection 

 it is well to note Darton's 7 statement that "The Helderberg 

 (=Decker Ferry in part) limestone usually lies on and merges 

 into the Longwood shales." Kummel and Weller 8 state: "The 



1 N. Y. State Pal. An. Rep't. 1903. p. 345, 346. 



2Geol. N. Y. 1st Dist. 1843- p. 354- 



3 N. Y. State Pal. An. Rep't. 1902. p. 1175. 



4 N. Y. State Pal. An. Rep't. 1903. p. 345. 



5 Geol. Soc. Am. Bui. 1903. 5: 382. 



6 See Grabau, N. Y. State Mus. Bui. 92. 1906. p. 125. 



7 Geol. Soc. Am. Bui. 1893. 5: 391. 



? Geol. N. J. An. Rep't. 1901. p. 41. 



