44 NEW YORK STATE MUSEUM 



cavelike form into which surface streams disappear (such as Pom- 

 pey's cave near High Falls), (d) mud crack surfaces (in lower 

 beds) , (e) occurrence of the fossil Leperditia alta. 



Its abundant jointing and the tendency to develop solution cav- 

 ities from them is considered an objectionable character. 



(i8) Cobleskill and cement beds (limestone). It is not pos- 

 sible without the most painstaking, comparative, chemical and pale- 

 ontologic research to differentiate the cement layers from the 

 inclosing beds and to assign them all to the subdivisions that are 

 recognized in some previous publications,^ as the (a) Rondout 

 cement (b) Cobleskill limestone, (c) Rosendale cement, and (<i) 

 Wilbur limestone. There are, however, two workable natudal ce- 

 ment beds, both at Rondout and at Rosendale, with a nonworkable 

 layer between each case, and also one between the lower 

 and the next underlying formation. Whether the two cement beds 

 at Rondout represent the Rondout and the Rosendale horizons 

 with the Cobleskill between, or whether they should both be re- 

 garded as Rondout with Cobleskill below, can not concern our 

 present problems. i\nd again, whether or not the two cement beds 

 at Rondout are the same two that appear at Rosendale, or whether 

 they are equivalent only to the upper one with a new lower bed 

 (The Rosendale) added in this area and then with the Cobleskill 

 between these two as claimed by Grabau, does not alter the plain 

 fact that the whole series is a physical unit. It is a gray, rather 

 close texture limestone, resembling the ^lanlius proper, and con- 

 tains few fossils. It is perhaps even better yet to group all of 

 these limestone beds below the Coeymans into a single unit and 

 call it the Manlius series. 



(19) Binnezvater sandstone. Below the Manlius cement rock 

 series lies the 60-100 foot Binnewater. It is chiefly a well bedded 

 quartz sandstone, almost a quartzite in the upper beds with more 

 shale in its lower portion, in color varying from white to greenish 

 yellow and brown. The rock is rather porous in certain beds and 

 especially along the bedding planes and is not well recemented 

 where crushed by crustal movements. It is confined to the Rondout 

 valley. 



(20) High Falls shale.^ Greenish to red argillaceous to sandy 

 shales. The exposures are often a brilliant red while the rock 



IN. Y. State Mus. Bui. 92 (Grabau). p. 311-13; N. Y. State Mus. Bui. 80 

 (Hartnagel), p. 355-58; N. Y. State Mus. Bui. 69 (Van Ingen and Clark), 

 p. 1 184, 1 185. 



2 The term given by Hartnagle. X. Y. State Mus. Bui. 80. p. 345- 



