54 ROCHESTER ACADEMY OF SCIENCE. [Jan. II, 



the Olean conglomerate of Allegany Co., New York, which is as 

 follows : 



" I. Olean conglomerate. 



2. Gray sandstones and sandy shale. Pocono type 175' 



3. Cireenish-gray sandstones and red and gray 



shale. Catskill type 225' to 400' 



4. Massive flat pebble conglomerate. Catskill type 25' to 425' 



5. A repetition of No. 3. Catskill type 125' to 550' 



6. Shales and flaggy sandstones. Chemung type 250' to 8oo"'(') 

 In reference to the correlation of this and other sections the 



author wrote : " In designating the different divisions on these sections, 

 it must not be understood that the rocks belong unquestionably to 

 the groups indicated. It is to be remembered that the divisions 

 between Pocono, Catskill and Chemung are purely arbitrary through- 

 out all the country under examination, for there seem to be no /c'.r- 

 tyire (faia, either lithological or palseontological, to indicate exactly 

 where the dividing lines should be drawn. Red rocks are evidently 

 no sure guide, for an abundance of red is found in one locality or 

 another in all these groups." (') 



In 1888 Professor Henry S. Williams published a Bulletin on 

 "The Genesee Section, New York," (^) in which the rocks of Alle- 

 gany Co., N. Y. are described and compared with the Bradford sec- 

 tion of Pennsylvania. A flat pebble conglomerate with some red jasper 

 pebbles is described from near the head of Wolf creek, west of West 

 Clarksville, which lies between 1,950' and 2,000' A. T. {*) 



About five miles south of the Wolf creek conglomerate and north 

 of Little Genesee is a conglomerate composed of round and larger 

 pebbles forming the so-called ''rock city." The Professor says : 

 "Chemung fossils were rarely seen above the horizon of the first 

 (Wolf creek) conglomerate and but for a short distance. After the 

 green, micaceous and flaggy shales, and the soft, red iron shales had 

 fairly set in, the Chemung fauna ceased." 



"With the incoming of the second conglomerate of Little Genesee 

 ' rock city,' there was deposited a coarse mixture of clay, iron ore, 

 and yellow sand with fossils. This ferruginous sandstone is charac- 



(i.) Ibid., p. 639. 



(2.) Ibid., p. 639; also, see plate I, section i. On p. 640, for the Bradford section, Carll 

 makes the top of the Catskill 250' below the base of the Olean conglomerate, which agrees closely with 

 Ashburner's 252'. Hut Carll calls the Catskill 320' thick instead of 250', so that the top of Carll's 

 Chemung is 570' below the base of the Olean conglomerate, against .-Vshburner's 502'. 



(3.) Bull. U. S. Geol. Surv., No. 41. The title page gives the date of publication as 1887 ; but 

 although the copy was transmitted to the Survey on August 2, 1886, owing to delay, it was not pub- 

 lished until the latter part of 1888. 



(4.) Ibid., p. 86. 



