90 THE DEVONIAN AND CARBONIFEROUS. f bull. 80. 



A detailed description of each bed is then given. Coal VIII is re- 

 garded as the " parent bed of all the Upper coal in Ohio, remaining in 

 existence as a flourishing swamp from the beginning of the epoch until 

 its close." 



The conditions of the Upper Coal Measures during deposition are 

 treated at length, and the author is led to the following conclusions: 



(1) The great bituminous trough west of the Alleghauies does not owe its basin 

 shape primarily to the Appalachian Revolution. 



(2) The Coal Measures of this basin were not united to those of Indiana and Illi- 

 nois at any time posterior to the Lower Coal Measure epoch, and probably were 

 always distinct. 



(3) The Upper Coal Measures originally extended as far west as the Muskingum 

 River, in Ohio. 



(4) Throughout the Upper Coal Measure epoch the general condition was one of 

 subsidence interrupted by longer or shorter intervals of repose. During subsidence 

 the Pittsburg marsh crept up the shore, and at each of the longer intervals of 

 repose pushed out seaward upon the advancing laud, thus giving rise to the suc- 

 cessive coal-beds of the upper coal measures. 



(5) The Pittsburg marsh had its origin at the east. 



I. C. White, 1 in 1874, before the same society, discussed the Coal 

 Measures of western Virginia and Pennsylvania. 



Two sections .are given from the region under jsonsideration, one from 

 the eastern and one from the western flank of the " Dividing Ridge," 

 an elevation between Morgantowu and Wheeling, rising in Pennsyl- 

 vania and extending south into West Virginia. The eastern section lias 

 a thickness of 800 feet in the Upper Barren group and 340 feet in the 

 Upper Coal group ; total thickness, 1,140 feet. The western section has 

 a total of 822 feet, 544 feet in the Barren group and 278 of the Upper 

 Coal. The sections show the well known fact that the coals and sand- 

 stones in this district thin out toward the west, while the limestones 

 thicken up. The eastern section in Monongalia County is described in 

 detail. The upper sandstones and shales are very coarse, showing that 

 that they were deposited by pretty strong currents. 



The different thicknesses aud characters of the various coal beds are 

 fully given. 



In 1875 J. P. Lesley, 1 State geologist of Pennsylvania, prepared a 

 brief digest of the state of classification and nomenclature of the rocks 

 in New York, Ohio, and Pennsylvania at that time. The article might 

 be quoted entire were there space, as no further condensation of the 

 statements can be satisfactorily made ; but a single scheme of equiv- 

 alents will suffice to show the ideas of the author as to correlations at 

 the beginning of the second survey of Pennsylvania. On page 97 we 

 find— 



'White, I. C. : Notes on the Upper Coal Measures of western Virginia and Ponnslyvania. Jiew York 

 Lyceum Nat. Hist., Anuals, vol. 11, 1874, pp. 46-57. 



"Second Geol. Survey of Pennsylvania, 1874, Report of Progress, I: Note on the comparative geol- 

 ogy of northeastern Ohio and northwestern Pennsylvania, and western New York, pp. 57-108. 



