T. G. White— Original Trenton Rocks. 431 



usually found lying with the ventral surface uppermost. Each 

 layer was separately measured and liberally sampled, and the 

 successive faunal lists, measurements, and descriptions of the 

 lithologic variations of the limestone are enumerated in the 

 paper. The total thickness of the Trenton Falls section thus 

 obtained is 325 feet. Of this, the upper twenty feet consists 

 of heavy-bedded, light gray, coarsely crystalline limestone, very 

 pure, and composed of comminuted fragments in which few 

 species can be recognized. The beds are separated by slightly 

 bituminous thin shaly partings, like the similar strata near 

 Montreal, Canada, and these contain numerous remains, espe- 

 cially crinoids and Acidaspis Trentonensis^ — the latter not 

 seen lower in the mass. 



The lower strata of the Trenton formation are not seen at 

 Trenton Falls, and following down stream, no outcrop of any 

 considerable thickness is found until Rathbone Brook is 

 reached, 3J miles below Poland, where a section of over 137 

 feet is afforded in the bed of the brook. Here the limestone 

 is thin-bedded but shows more distinctly marked zones than at 

 Trenton Falls ; is light colored, and frequently sandy in tex- 

 ture. A short distance north of where the brook enters West 

 Canada Creek, an outcrop on the edge of the creek yields a 

 section of Calciferous, Birdseye and Black River, respectively 

 8, 9-|- and llf feet in thickness. The Chazy is lacking, appar- 

 ently through non-deposition. The Black River is barren at 

 the base, but above contains abundant Illcenus crassicauda, 

 Leperditia fabidites^ Avicida trentonensis^ Rajphistoma ameri- 

 cana^ Cyprieardites obtusus and C ventricosus^ Zygospira 

 recurvirostra^ Strophomena filitexta^ Rhynchotrema inoequi- 

 valvis, Rathyurus exta^is, Oyrtoceras temnstriatus, etc., twenty- 

 six species being noted in all. 



In both sections of the Trenton, the fossiliferous portions 

 tend to occur in lenticles, sometimes composed entirely of frag- 

 ments of one or two species. Orthis testudinaria^ always 

 abundant, frequently occurs in this way. The transition 

 between the light colored fossiliferous lenticles and the dark 

 compact limestones is often very abruptly marked, the lenticles 

 evidently resulting from depressions filled with fragments in 

 an otherwise even surface of the finest carbonaceous lime sedi- 

 ments. Several well characterized zones occur, but specialized 

 faunal zones are not frequent. In the Rathbone Brook series 

 Prasopora of a large tubed variety and Stenopora fibrosum 

 are especially abundant in the lower 30 feet. Holopea sym- 

 metrica and Trematis terminalis are rather abundant at from 

 15 to 30 feet above the base of the section. Conularia trento- 

 nensis is first found at 30 to 50 feet. Parastrophia hemipli- 

 caia, which occurs just above the top of the Black River at 



Am. Jour. Sci.— Fourth Series, Vol. II, No. 12. — December, 1896. 

 31 



