LOWER OMSK ANY OF NEW YORK 305 



Beecher discovered in so well known a region as Becraft mountain, east 

 of the Hudson river, and just south of Hudson, New York, a new geo- 

 logical horizon and a fauna intimately connected with the Becraft of 

 the Helderbergian below and the true, or Hipparionyx, Oriskany above. 

 Regarding this horizon, Doctor Beecher* writes : 



"In 1890. . . in the Becraft's Mountain region of Columbia county, New York, 

 a fauna was discovered by the writer, which in many respects is new to the State. 

 Its affinities are with the Oriskany, but its geological position is below the true 

 Oriskany sandstone. It appears to include a part, at least, of what has been re- 

 feired to the Lower Helderberg group on account of its lithological characters and 

 upon insufficient paleontological grounds. The fauna of the Upper Pentamerus in 

 its original locality (Schoharie, New York) has previously been recognized to con- 

 tain several species quite distinct from the Scutella, Shaly, and Lower Pentamerus 

 limestones, which represent the typical Lower Helderberg group. Moreover, as 

 the complete fauna has remained unknown and the series has been confused with 

 the underlying Scutella limestone, no exact correlations have been made. 



" From the fossils now known from Becraft's mountain and several other local- 

 ities, it is evident that the relations of the fauna contained in the upper beds of 

 the series above the Scutella limestone and just below the Oriskany sandstone are 

 with the latter, and not with the Lower Helderberg group. . . . 



"At Becraft's mountain the rock is a hard, cherty, arenaceous limestone, weath- 

 ering into a rotten fine-grained sandstone [a few feet in thickness], preserving the 

 molds of the fossils or their silicified replacements. . . . At Port Jervis, New 

 York, it is in general still more calcareous, although there are some cherty layers, 

 and many of the fossils are silicified. Here, too, the series is continuous from the 

 Oriskany sandstone down through the trilobite beds of Mather, Horton, and Bar- 

 rett. The arenaceous character of the beds gradually decreases downwards, carry- 

 ing the typical Oriskany species into the Dalmanites denlatus layers and below, and 

 making the whole series of this group at Port Jervis probably over two hundred 

 feet in thickness, of which one hundred or more belong to the Lower Oriskany." 



Barrett f gives the thickness of the Oriskany formation at Port Jervis, 

 New York, as "100 feet; it is probably more, the higher arenaceous 

 layers of the division having been removed by glacial action." Ries 

 gives the thickness for the same region as " about 125 feet." The known 

 Oriskany fauna from this region is meager, but for the present it is re- 

 ferred to the Upper Oriskany. The transition, however, from the Becraft 

 limestone to the Oriskany in the Port Jervis region is apparently unin- 

 terrupted. Doctor Barrett writes : 



"From the top of Trilobite Ridge [his uppermost Upper Pentamerus bed, or 5c, 

 with a thickness from 5 to 10 feetl to the foot of the Cauda-galli ridge, northwest 

 of it, Oriskany fossils predominate. There is, however, such a gradual shading 

 off from one into the other, that no one whose knowledge of the Lower Helderberg 

 and Oriskany strata had been acquired by the study of their exposures in this 



* Araer. Jour. Sci., vol. xliv, 1892, pp. 410, 411. 

 t Ann. Lye. Nat. Hist. N. Y., vol. xi, 1876, p. 294 



XLIV— Bull. Geol. Soc. Am., Vol. 11, 1899 



