

williams 1 WHITE, 'FONTAINE, LESQUEREUX. 103 



The authors recognize as of Pocono age coal beds in numerous locali- 

 ties in Pennsylvania, Virginia, and West Virginia, and they correlate 

 the Mauch Chunk formation, or " Subconglomerate," with the Chester 

 and St. Louis limestone group of Illinois, Indiana, and Kentucky, the 

 Waverly group of southern Ohio, and the Cuyahoga shale and Berea 

 grit, of northern Ohio. 1 



it is not proposed here to discuss the value of fossil plants as a means 

 f correlation. The whole subject of the classification, distribution, 

 ange and association of fossil plants is under investigation by an ex- 

 pert botanist. 



Several interesting problems of correlation depend much upon the 

 evidence of fossil plants: as the determination of the true relations of the 

 arenaceous deposits between the marine Devonian and the Carbonifer- 

 ous formations of the Appalachian province,the correlation of the Upper 

 Paleozoic formations of the Acadian province, and the differentiation 

 of the Permian from the Upper Coal Measures of the Appalachian areas. 

 One work, however, may be cited as an illustration of the kind of mod- 

 ifications in classification suggested by fossil botany. In the year 

 1880 the results of Mr. Leo Lesquereux's work on the fossil plants of the 

 Coal Measures of Pennsylvania were published in Report P. 2 Several 

 of the chapters, particularly those on stratigraphy, were edited by the 

 State Geologist, J. P. Lesley. 



The greater part of the work is devoted to descriptions of the 

 plants. At the close of the volume of text a list is given of the " Liter- 

 ature of the United States Coal Flora" (including Devonian), with 145 

 titles. Under u General remarks," chapter 2 is entitled u On the geo- 

 graphical and stratigraphical distribution of the plants of Carbonifer- 

 ous age*," 3 and at its close a "Table of distribution" gives the vertical 

 range and geographical distribution of 590 .species of plants. The 

 arrangement of the columns expressing vertical range and classifica- 

 tion presents in a concise form the results of Mr. Lesquereux's long, ex- 

 haustive and most careful study of the paleozoic plants of the United 

 States. 



The following is the classification : 4 



'■S 



I. PRE-CARBONIFEROUS. 



Devonian. 



1. { Chemung (top division of No. VIII)=Middle Devonian. 

 Cat shill (No. IX), Upper Devonian. 



2. Pocono Sandstone (No. X), including, in Pennsylvania, Sideling Hill Tunnel, 

 Huntingdon County ; Red shale, below Pottsville (Mount Carbon) ; Lehigh Gap, below 

 Mauch Chunk; banks of the Susquehanna, above Pittston; (Lewis Tunnel and New 

 River group, West Virginia.) 



'The Permian or Upper Carboniferous Flora of West Virginia and Southwestern Pennsylvania, 

 pp. 626-627. 



2 Description of the Coal Flora of the Carboniferous formation in Pennsylvania and throughout the 

 United States. Vol. 1, cellular cryptogamous plants, Fungi Thalassophytes, Vol. 2, vascular cryptog- 

 amous plants, Calamaria, Filicacea (Ferns). By Leo Lesqueieux, pp. 694. and atlas, 87 plates. 



3 Edited by J. P. L., pp. 617-635. 



4 Pp. 636-657. 



