THE GRAPTOLITE (LEVIS) FACIES OF THE BEEKMAN- 

 TOWN FOKMATION IN KENSSELAER COUNTY N. Y. 



BY RUDOLF UUEDEMANN 



La masse achisteuae de la vallee de ('Hudson, renferniant de nom- 

 breiix gruptoittca, I' ccistence de ces fossilcs sur Vhorizim de la fnune 

 priinordtale serait unfnit particulier on continent americain et digne 

 dc la plus grande attention. II reste.rait d etablir lea relations, solt 

 jtnleontologiques, soil stratigraphiquea, entre ces graptolttes de la 

 vallee de I'Hudaon et ceux de la Puinte L^vla, prda Quebec. 



Barran'db. 1S62 



DKSCRIPTIO.X OF THE EXPOSLHE 



The section described in this paper is exposed along the Deep 

 kill, a small eastern tributary of tlK' Hudson river, and begins 

 about a quarter of a niiU* cast of the small settlement known 

 as Grant Hollow in the northwestern part of Rensselaer county. 



a In ascending the Deep kill valley from Grant Hollow, the 

 first exposure is a small outcroj) in the south bank of a few 

 feet of deep black mudstone giving conchoidal fracture. This 

 rock has furnished no fossils. Another outcroi), where are 

 exposed somewhat contorted dark gray, sandy, thinly bedded 

 shales with a few intercalations of argillaceous sandstone, is 

 30 feet farther up. These strata also proved to be barren of 

 organisms. 



The continuous section begins 700 feet farther east, on the 

 north side of the creek. The beds of this exposure are, in con- 

 trast to those met with farther up and down the creek, free from 

 flexures and dip uniformly N 11G° E at an angle of 24°. It is 

 apparent that the extremely heavy bedded, hard silicious beds 

 and the limestones prevailing in this section protected tlie 

 shales from being thrown into the many small, closely packed 

 folds so characteristic of the softer and more j (liable terranes 

 of the region. There is no cleavage in these beds; and the 

 islickensides, which often run subparallel to the bedding planes 

 and obliterate or at least distort all organic remains in so many 

 outcrops of the Trenton, Utica and Lorraine shales in the Hud- 

 son river region, are frequent only where the heavy (juartzose 

 banks have slipped along the thin shale partings. To th<^ 

 absence of these antagonists of tin* ]iah'oiitologist tin* beautiful 



