THE STHATIGRAPHIC SUCCESSION OF THE FOSSIL FLORAS OF 

 THE POTTSVILLE FORMATION IN THE SOUTHERN ANTHJSA- 

 CITE COAL FIELD, PExNxNSYLVANIA. 



By David White. 



IXTRODUCTIOX. 



APPLICATION OF THE TERM "POTTSVILLE FORMATION:"' 



The Pottsville formation, or "Pottsville series" or ''Pottsville eon- 

 glomerate," as it has more often been known, is a group of largel}" 

 arenaceous beds of highl}^ variable thickness which, in eastern Penn- 

 sylvania, lies between the Mauch Chunk red shale, or distinctly Lower 

 Carboniferous, and the Lower Productive Coal Measures, or distinctly 

 Upper Carboniferous. Besides the term employed for these terranes 

 in this report, this formation has been otherwise designated the 

 ""Serai conglomerate" or '' Great conglomerate," b}' the early Penn- 

 sylvania geological surve}';^ the "Pottsville conglomerate," and locally 

 the "Lykens series," by the second geological survey;^ the "Con- 

 glomerate series" by many other geologists;^ and more recently it 

 has been known in the northern portion of the Appalachian trough 

 as the "Pottsville series," the modified name published by Dr. L C. 

 White.* The early name "Serai" is hardly adaptable to present use, 

 CD since it was applied by Rogers to the entire Carboniferous series above 

 ^ the red shale in the anthracite region, the lower portion being distin- 

 I guished from the remainder only by the addition of the word "con- 

 ^ glomerate." The claims to consideration of "Great conglomerate" 

 '21. and "Conglomerate series" have been rejected by most geologists, 

 — ^ since throughout the greater part of its extent the formation is 

 found to be productively coal-bearing, while in certain districts it 

 contains little or no conglomerate. Nevertheless, the magnificent 

 development of the terranes displayed at Pottsville, which is cited by 

 all authors as the type locality under the various names, and from 

 which the later names "Pottsville conglomerate" and "Pottsville 

 series" were derived, is overwhelmingly conglomeratic, as well as 

 deficient in profitably workable coal. In the various districts of the 



' Rogers, Geol. Pennsylvania, Vol. 1, 185cS, pp. vii, 109, 146, 148; Vol. II, Pt. I, pp. 16, 17. 

 -.\iinual Kept., 1886, Pt. Ill; Summary Final Report, 1896, Vol. Ill, Pt. I; Atlas Southern Anthracite 

 Field, Pts. I-VI. 

 3 Fontaine, Am. Jour. Sci., 3d series, Vol. VII, ISTti, pp. 4.59, 573. 

 <Bull. U. S. Geol. Survey No. 65, 1891, p. 179. 755 



