T. C. Brown — Shawangunk Conglomerate. 465 



Darton, while describing the geology of Ulster county,* 

 tentatively correlated these beds with the Clinton, Medina, 

 and Oneida, but he states that : " The evidence as to the precise 

 equivalency of these beds between the Shawangunk grit and 

 Salina formation, in Ulster county, is unsatisfactory. No 

 fossils have been found and the physical characters are not 

 wholly distinctive. The quartzite and calcareous upper mem- 

 ber is thought to represent the Clinton formation, for the upper 

 part of this horizon is characterized by somewhat similar beds 

 in western New York. The lower red beds may also be 

 Clinton, but as they appear to expand into a series of red sand- 

 stones southward, it is suggested that they are of Medina age." 



Careful stratigraphic work on the overlying limestone beds 

 disclosed an error in the early correlations of these bedsf and 

 cast a doubt upon the supposed age of the subjacent sand- 

 stones, shales and conglomerate. When an Eurypterid fauna 

 was discovered in the partings of the Shawangunk conglomer- 

 ate this bed was definitely correlated with the Salina of western 

 New York,;}; and the overlying beds must, therefore, be of 

 Salina age or later. Some doubt seems to exist, however, con- 

 cerning the relation of these shales and sandstones to the under- 

 lying Shawangunk and to the overlying limestones and cement 

 beds. These contacts have frequently been described, but 

 the descriptions do not agree with the observation of the 

 writer, and a somewhat more detailed description of these 

 contacts or transitions may throw a little light on the relations 

 of the beds. 



A great unconformity has always been recognized between 

 the Shawangunk conglomerate and the underlying Hudson 

 River shale in Ulster county, but no detailed description of this 

 contact is known to the writer. The upper contact of the 

 Shawangunk conglomerate with the overlying shale (now gen- 

 erally called the High Falls shale in this vicinity) has been 

 described in detail by Hartnagel, but his description does not 

 agree with the observations here given. He states that : " In 

 the eastern section these shales are entirely devoid of pebbles, 

 generally of a bright red color and uniform in character, 

 specially near their base. On exposure to the atmosphere they 

 break into small angular fragments which are easily washed 

 away, leaving the sloping surface of the conglomerate beneath 

 clean and white. ... It is evident then that there is a very 

 marked change in the character of the sedimentation follow- 

 ing the conglomerate, suggestive of a hiatus at this point."§ 



* Report of the New York State Geologist, 1893, pp. 307-309. 

 f C. A. Hartnagel, Rept. N. Y. State Paleontologist, 1903, pp. 342-358. 

 % Science, Nov. 16, 1906 ; N. Y. State Mus. Bull. 107, pp. 295-310. 

 § C. A. Hartnagel : Notes on the Siluric or Ontario Section of Eastern New 

 York, Rept. N. Y. State Paleontologist, 1903, p. 345 (1905). 



