1032 



NEW YORK STATE MUSEUM 



around its base are steeply inclined, and contorted from a move- 

 ment previous to the deposition of the shales and limestones 

 upon them. 



Hall in 1850 1 expressed a doubt as to the reported uncon- 

 formity between the Hudson river and Lower Helderberg strata, 

 since " in Becraft's mountain the strata of this age [Lower 

 Helderberg and Water-lime] lie inclined above the Hudson river 

 group, and there appears no positive evidence of their uncon- 

 formability." 



The most complete review of the literature of Mt Becraft 

 and the neighboring region on both sides of the Hudson is given 

 by Davis in his article on the folded Helderberg limestones east 

 of the Catskills. 2 From a study of this region on the west bank 

 of the Hudson, he concludes that the contact between the Hud- 

 son river shale and the Wateriiine is a conformable one, though 

 he considers this conformity difficult to understand in view of 

 the variation of the strata. 



In 18S3 3 Davis published the hist geologic map of Becraft 

 mountain and gave the hrst comprehensive account of its strati- 

 graphy and structure. The map is accompanied by a number of 

 cross sections, which give the main structural features of the 

 range. He recognizes the Waterlime (Manlins) resting on the 

 Hudson river beds and discusses at length the evidence for and 

 against the unconformity between the two. While leaning toward 

 the acceptance of an unconformity, he nevertheless considers the 

 evidence for it still insufficient. Above the Waterlime he recog- 

 nizes the Lower Pentamerus (Coeymans'i . the Delthyris shaly 

 (New Scotland), the Upper rentamerus (Becraft), the Cauda- 

 galli (Esopus) and the Corniferous (Onondaga). He did not 

 differentiate the Kingston (Port Ewen) and Oriskany from the 

 Becraft. nor the Schoharie from the Esopus. He also recognizes 

 the complicated southeastern portion of the mountain. 



Clarke 4 has published the latest and most complete map of 

 Becraft mountain extant. In this all the formations are de- 



1 Palaeontology of New York. 1850. 3:39. 



' Mus. Comp. Zool. Bui. v. 7 (Geol. Ser. v.l) p.311-30. pl.12-13 



3 Am. Jour. Sci. ser. 3. 1SS3. 26:3Sl-89. 



4 Clarke, J. M. Oriskany Fauna of Becraft Mountain, Columbia County. X. V. 

 X. Y. State Mus. Mem. 3. 1000. 



