xiam8.J HALL. 123 



farther examination proved its existence, as well as the occurrence of 

 ligher formations. From these additional facts a map was constructed, 



>lored to represent the different formations. The Catskills consist of 



series of nearly parallel synclinals and anticlinals, with a southwest 

 and northeast strike, running from the base of the Catskill range u to 

 the western limit " of the red rocks in Chenango County. This con- 

 tinues to the western part of the State, but before reachiug the bound- 

 ary of western New York and Pennsylvania, it probably thins out 

 entirely. In the southern part of New York State the synclinals show 

 traces of the Coal Measures, while others are cut down to the Chemung. 



The author states the difficulties that have arisen in determining the 

 relation of the Chemung and typical Catskill. In some localities the 

 Chemung fauna runs above its apparent horizon, and even mingles 

 with Carboniferous forms. This fact is especially important when we 

 attempt to determine the limit between the Devonian and Carboniferous 

 formations. In the section exhibited which runs across the Catskill 

 range from Schenevus to Glasco, the Portage and Chemung rocks have 

 a thickness of over 2,000 feet, the Red Rocks of the Catskill about 3,000 

 feet, and the Vespertine beds about 800 feet. 



He stated in 1880 x that he found long ago that the Catskill Moun- 

 tains of New York consist of Devonian rocks of Chemung and Catskill 

 epochs, resting unconformably on Silurian rocks. Mr. Arnold Guyot 

 in his observations found that the highest points of this region were on 

 Slide Mountain, 4,205 feet, and the Panther, 3,828 feet above tide level. 

 "As to structure, the beds show weak plications whose axes are parallel 

 with those of the Alleghany system, but the mountain ranges were at 

 right angles to the system, or from northwest to southeast." This 

 anomaly is explained by erosion. " The general level descends west- 

 ward." 



The work of the Second Pennsylvania Survey had been conducted, 

 up to 1880, or up to the time of preparing the reports published in 1880, 

 on the plan that correlations could best be made by lithologic and 

 stratigraphic means. Frequently one meets with expressions of lack 

 of confidence in the evidence offered by the fossils. 



In the correlation of the Coal Measures and as far down as the Catskill 

 the fossils were not discovered frequently enough to serve as satisfac- 

 tory means of correlation. In this case lithologic character, thickness, 

 and stratigraphic order were the data which by aid of actual altitude of 

 the strata in individual sections enabled the geologist to trace dominant 

 formations from one township to another and from county to county. 

 But as the work progressed, different geologists having charge of groups 

 of two or three counties, the correlations at the edges of contiguous 

 counties were constantly presenting disagreements. 



The formations, where fossils were not present stubbornly to resist 



'Hall, James: The geology and topography of the Catskill Mountains. Am. Nat, vol. 14, 1880, 

 pp. 612-613. J p. 



