104 THE DEVONIAN AND CARBONIFEROUS. [bull. 80. 



3. Subcon glomerate : Mauch Chunk, No. XI, including Fontaine's conglomerate se- 

 ries of West Virginia, and localities in Alabama, Tennessee, Arkansas, Illinois, Ches- 

 ter Group ; Indiana, Chester Group ; and Megalopteris beds of Ohio and Illinois. 



4. Jnterconglomerate, No. XII, Campbell's Ledge, near Pittston, east Pennsylvania; 

 Shamokin Gap, east Pennsylvania ; Jackson Shaft bed, Ohio ; Cuyahoga bed, Tal- 

 madge Summit beds,' Ohio ; Youngstown, Ohio. 



II. COAL MEASURES PROPER. 



1. Anthracite fields. 



5. Beds A, B, and C, at Archibald, Carbondale, etc. 



6. Beds D, E, F, at Pittston, Wilkes-Barre, Scranton, etc. 



7. Bed G, Wilkes-Barre, etc. 



8. Upper Anthracite (Salem, etc.). 



9. Rhode Island, etc. 



2. Bituminous fields. 



10. Coal A, B, above the Conglomerate (both beds often united), at Murphysbor- 

 ough, Neeley ville, Marseilles, Colchester, Morris, Mazon Creek, Centralia Shaft, Van- 

 dalia, Illinois,* at Burnt Branch of Caney, etc., Kentucky; at Massillon, Ohio. 



11. Coal C (which is sometimes united to B), at Clinton, Missouri ; Canuelton, west 

 Pennsylvania. 



12. Fourth Coal (nuder the Barren Measures), at Duquoin, St. Johu, Illinois ; Nel- 

 sonville, Ohio; Coshocton, Ohio; Sullivan County, Indiana. 



V.i. Upper Coal (top of the Barren Measures), at Pittsburg, Pennsylvania ; Pom- 

 eroy, St. Clairsville, Barusville, Ohio ; Carmi, Illinois; Grayville and New Harmony, 

 Indiana. 



In this classification the base of the Pocono is regarded as the lowest 

 formation of the Carboniferous system, although the line separating it 

 from the Catskill below is stated to be " purely empirical." ' 



The Kinderhook Group of Illinois " is probably referable to the Po- 

 cono." 2 



J. P. Lesley, 1886, gave some valuable statistics regarding the Pitts- 

 burg coal region. 3 



The Pittsburg Coal Measures have an aggregate thickness of 2,000 

 feet, containing 15 persistent workable coal seams. Their outcrop lies 

 in a northwest and southeast direction across the State, forming a 

 series of concentric curves, due to the peculiar way in which the sur- 

 face has been eroded. The Pittsburg seam is the fifth in descending 

 order. It has been preserved from eroding effects in the southern 

 part of the region only. The author sees no reason for disbelieving 

 that this seam with its companions once extended into New York and 

 northern Ohio, and even crossed Lake Erie and Lake Ontario into 

 Canada, and he is firmly convinced that " they once had a quasi-con- 

 tinental outspread." 



The Pittsburg seam has a thickness of 12 feet at Connellsville, Penn- 



1 Lesq., Desc. Coal Flora, p. 622. 



2 Ibid., p. 624. 



3 Lesley, J- P, : The Geology of the Pittsburg coal region. Am. Inst. Mining Eng., Trans., VoL 

 14, 1886, pp. 618-656, plate. 



