290 



NEW YORK STATE MUSEUM 



Feet Total 



Coeymans limestone 50-463 



Massive, bluish gray limestone forming the upper 

 part of the conspicuous cliff to the west of New 

 Salem. This limestone forms the upper part 

 of the prominent cliff which may be followed 

 from southwest of New Salem around the north- 

 eastern and northern ends of the Helderbergs 

 to Altamont. 1 The fossils are : 



1 Sieberella galeata (Bah ) H. & C— Pentamerus galeatus Hall a 



2 Uneiniilus mntabilis (Hall) H. c(- C. 



3 Atrypa reticularis (Linn.) Dal. 



iProfessor Harris has recently given the thickness of the Coeymans lime- 

 stone on Countryman hill as 32 feet [Am. Pal. Bui. 19, p. 26] and that of 

 the Manlius limestone in the neighborhood of the Indian Ladder as 63.7 

 feet [ibid., pi. 1, fig. 8]. The total thickness for the two formations in 

 Professor Harris's section is 95.7 feet and in mine 96 feet, which shows that 

 there is scarcely any difference in the sections except that Professor Harris 

 drew the line of separation between the Manlius and Coeymans limestones 

 at a higher horizon than I did between the transitional Tentaculite and 

 Pentamerus limestones. In my Helderberg sections it was attempted to 

 divide this part of the limestones into the Tentaculite and Pentamerus as 

 originally classified by Gebhard [see Mather. Geol. N. Y. 1st Dist. 1810, 

 p. 237, 238]. It was called Tentaculite limestone as high as Tentacu- 

 lite s g y r a c a n t h u s , S p i r i f e r vanuxemi or L e p e r d i t i a 

 a 1 1 a occur and then the first lithologic break above was considered the 

 base of the Pentamerus limestone. It is probable, however, that according 

 to this delimitation the top of the Tentaculite limestone is not synchronous 

 with the top of Vanuxem's "Manlius water lime group" [ibid.. Geol. X. Y. 

 3d Dist. p. 376. This formation was vaguely defined by Yanuxem in his 

 Third An. Rep't. 1839, p. 272 under the heading " Water Lime " as " the 

 water lime group of Manlius"], and after an examination of the typical 

 Manlius section I incline to the opinion that the top of the Manlius lime- 

 stone is stratigraphically higher than what was considered the top of 

 Gebhard's Tentaculite limestone of the Helderbergs. In his final report 

 Mather stated that "The Pentamerus limestone is a mass of rock some fifty 

 feet in thickness " which " forms a continuous stratum from the west line 

 of Schoharie county eastward to the Helderberg mountains in Berne and 

 Bethlehem." [Geol. N. Y. pt I, 1813, p. 317] and in a general way Mather's 

 description and thickness were accepted by me in delimiting the Pentamerus 

 limestone. Mather, however, did not clearly state the thickness of the 

 Tentaculite limestone which he called the upper member of the " Water- 

 lime group" and stated that "The upper part of the tentaculite limestone 

 is a black and dark grey slaty compact (in some layers subcrystalline) 

 limestone, in layers from an inch to a foot thick.*' while the middle part he 

 gave as " composed of slaty black layers of compact limestone, containing 

 an abundance of the Tentaculites o mat us [T. gyra- 

 canthusj, Cytherina a 1 1 a [L e p e r d i t i a a 1 1 a], O r t h i s 

 plica t a [Spirifer vanuxemi], and some of the Avicula 

 rugosa. These are characteristic species" [ibid., p. 350]. It was 

 thought that in a general way the upper part of Mather's Tentaculite lime- 

 stone corresponded with what I called the transitional Tentaculite; but 

 perhaps it represents the zone which Professor Harris has indicated be- 

 tween the limestones containing the Tentaculite fauna and the overlying 

 Coeymans or Helderbergian, in his sections from Manlius to the Helder- 

 bergs [loc. cit., pi. 1, fig. 8-8]. Charles S. J'r'osser 



