THE ORISKANY FAUNA OF BECRAFT MOUNTAIN, 

 COLUMBIA COUNTY, NEW YORK 



INTRODUCTION 



The existence of a fauna in the New York series linking together 

 in the character of its species that of the calcareous shales and lime- 

 stones of the Lower Helderberg and that which has been regarded as 

 pertaining to the normal Oriskany sandstone of Oneida county and 

 westward sections, was first brought to public notice in 1892, in a 

 paper published by Prof. Charles E. Beecher and accompanied by a 

 list of the species prepared by the writer.' 



The interesting bearings of this assemblage of species, its new 

 forms and new associations and its real importance in the correlation 

 of the lower Devonian are sufficient reason for presenting its char- 

 acteristics in detail. 



The fauna in its highest development is found at Becraft moun- 

 tain, about 2 miles east of the Hudson river, near the city of Hud- 

 son in Columbia county. Strata of the same horizon occur at other 

 localities in the state and carry some of the characteristic species which 

 appear in profusion on Becraft mountain. Such outcrops are found in 

 Ulster and Orange counties on the west side of the Hudson, but they 

 quickly disappear in the westward extension of the Oriskany formation. 



Chapter 1 



STRATIGRAPHIC STRUCTURE OF BECRAFT MOUNTAIN 



Becraft mountain has been the subject of geologic observation since 

 the early report of W. W. Mather on the geology of the first district 

 of New York (1842). A brief account of the succession and structure 

 of the rock beds will be found on page 351 of that work, and a very 



' Notice of a new Lower Oriskany fauna in Columbia county, N. Y. by C. E. 

 Beecher, with an Annotated list of fossils, by J. M. Clarke. Amer. jour. sci. 1892- 

 44:410-14. 



