﻿440 I. P. Bishop — Fossiliferous Limestones inChatham, iT. Y, 



no shale intervening, as far as I have been able to find. The 

 western arm is wrinkled into parallel anticlinals and synclinals. 

 On the western side of the arm, two narrow belts of shale, hav- 

 ing the lithological character of the graptolitic shales, are en- 

 closed between these parallel ridges of limestone. Over the re- 

 gion from Ghent westward the axes of the folds dip to the north 

 at an angle of 45° or 50°. At Kinderhook Lake there was some 

 evidence of a southward dipping fold. The width of the west- 

 ern arm of limestone ranges from three-fourths of a mile to more 

 than two miles. 



Limestone outcrops also at Eider's Mills and near Maiden in 

 the northern part of the country. I have not yet had time to 

 trace the western arm farther north than Kinderhook Lake, and 

 therefore do not know to which belt the latter outcrop should 

 be assigned. 



The color of the limestone of both arms is bluish gray or 

 dove-colored. It contains veins of calcareous spar which cross 

 the surface irregularly, giving it a checkered appearance. It 

 varies from massive thick-bedded limestone to calcareous shale. 

 In all localities where I have observed it, there are brecciated 

 layers present, made up of lenticular fragments of limestone, 

 pieces of shale, and siliceous material. These usually contain 

 limonite concretions, evidently changed from pyrites by oxida- 

 tion and having nuclei of organic matter. Interspersed with 

 the limestone are siliceous layers, both massive and thin-bedded, 

 some of which are nearly pure sandstone or quartzite while 

 others are calcareous. These do not resemble the Hudson River 

 sandstones mentioned above in color, texture or appearance, and 

 are undoubtedly distinct from them. It will be noticed that 

 the series is similar to that described by Mather* at Great 

 Neutin Hook, and probably belongs to the same system. 



The fossiliferous localities are three in number and all are in 

 the eastern belt. From the first, situated about midway between 

 Chatham and Ghent, only crinoid stems have been taken. 

 The second is situated at the crossing of the N. Y. & M. 

 R. R, two miles north of Chatham ; and the third a mile still 

 farther north, on the farm of Mr. Joel Angell ; and these two 

 have furnished the fossils mentioned below. They were first 

 noticed by me about April 1, 1886, at the R. R. crossing, and 

 at the upper locality a few weeks later. Some layers of the 

 rock are made up almost entirely of organic remains in which 

 gasteropods predominate. There are, also, crinoid stems in abun- 

 dance. Among the brachiopods there are several well-marked 

 valves of Leptcena sericea and Sirophomena altemata. The ex- 

 ternal markings of the gasteropods are so effaced by metamorph- 

 ism and weathering that it is very difficult to distinguish species. 

 * Geology of N. Y., Pt. IV, 1843. 



