GEOLOGY AND PALEONTOLOGY OP THE SCHOHARIE VALLEY 



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average 40 feet in thickness in the cement district, but south of 

 Kosendale give way to argillaceous and ferruginous sediments 

 (Longwood shales). The sandstone phase of this series overlaps 

 the congloijaerate north of Binnewater, indicating a more rapid 

 subsidence which prevented the formation of the conglomerate. 

 The highest bed of the series, a white quartzite, laps over all the 

 lower ones, appearing as far north as Wilbur bridge across the 

 Kondout, where it rests directly, on the Hudson river slates. This 

 formation appears thus to be much 

 later than the Clinton and if the con- 

 glomerate is early Salina, this bed too 

 is Salina. It is followed by the Salina 

 waterlimes (Eosendale bed) with an 

 abrupt succession indicating a rapid or 

 even sudden subsidence, so that only 

 the fine calcareous muds of which these 

 rocks are composed could be depos- 

 ited. That the surface of the floor 

 formed by these Shawangunk sand- 

 stones was not a level one is shown 

 by the varying thickness of the first or 

 Rosendale cement bed, which at Rosen- 

 dale is 20 feet thick, but at one point near Binnewater thins down 

 to 4 feet, though quickly increasing again. At the West Shore 

 railroad bridge across Rondout creek at Wilbur, the thickness of 

 this lower bed is lOJ feet. In many places the base of the Rosen- 

 dale cement is formed of a more or less crystalline lime sandrock, 

 a few feet in thickness. This has been called the Wilbur lime- 

 stone by Hartnagel. It contains a modified Niagaran fauna. 

 Throughout the cement region the Rosendale bed is succeeded by 

 a limestone bed varying from 10 to 15 feet in thickness, which 

 Hartnagel has identified with the Cobleskill limestone. This rock 

 is mostly a lime sandrock Avith large heads of H a 1 y s i t e s 

 eaten ulatus var. [fig. 29] , F a v o s i t e s n i a g a r e n s i s 

 [fig. 30] and S t r o m a t o p o r a sp., besides brachiopods, many 

 of which are of Niagaran affinities. 



Fig. 29 Halysites eaten u- 

 latus var. 



