372 REPORT OF NATIONAL MUSEUM, 1004. 



At this same meeting of the Association H. D. Rogers gave an 

 important paper on the origin of the coal beds. He here took the 

 ground that the singular constancy in thickness of the Pittsburg 

 coal bed and its prodigious range were strong^ 

 Forniatkftfo* coai, e adverse to any theory of accumulation by drift. His 

 idea was that the area now covered by the coal was 

 once an extensive flat, bordering a continent, beyond which lay a 

 Avide expanse of shallow but open sea; that these low flats were 

 occupied by peat bogs derived from and supporting a luxuriant growth 

 of Stigmaria, while along the land margin and the drier areas were 

 conifers, Lycopods, and tree ferns. The Stigmaria would thus form 

 a uniform mass of pulpy peat admixed with leaves and other easily 

 transported debris of the trees along the shores, but free from trunks 

 and coarse branches. 



To account for the shaly and sandy partings of the coal beds and their 

 numerous impressions of plants, he imagined a sudden sinking of the 

 land, producing thus a tidal wave from the open sea, carrying destruc- 

 tion to the forest growths, and on its return dragging back and spread- 

 ing out over the sea bottom, and hence over the accumulated peat beds, 

 sand, gravel, and silt, together with floating trunks of trees, all of 

 which go to make up the roof slate and other partings in the beds. A 

 period of tranquillity followed; another bed of peat accumulated, and 

 so on. His theoiy differed from those of Buckland, Beaumont, Lyell, 

 and others in excluding from the coal-making materials the trunks and 

 branches of the more woody trees and the catastrophic interruptions 

 in the growing processes due to earth sinkings and earthquakes. 



He further accounted for the difference in volatile constituents 

 between the coal of the eastern and western beds on the supposition 

 that the former were debituminized by the action of steam and gaseous 

 matter emitted through the crust of the earth and cracks and crevices 

 formed during the undulation and permanent bending of the strata, 

 resulting in the formation of mountain ranges. 



Prof. W. B. Rogers, at this same meeting of the association, had an 

 important paper on the connection of the thermal springs, in Virginia, 

 with the anticlinal axes and faults. He recognized the work of the 

 European geologists in connecting similar phenomena 

 Th'eniiai iprings, with areas of terrestrial disturbance, and then pro- 

 ceeded to show that, with but few exceptions, the 

 thermal springs of the Appalachian region issue from the steep dip- 

 ping or inverted strata on the northwest side of the anticlines. From 

 this he deduced the general law that the decidedly thermal springs of 

 Virginia issue from the lines of anticlinal axes or from points very 

 near such lines. These views he regarded as in harmony with those 

 of Arago and Bischoff. From those of Daubeny they differed, seem- 

 ingly, in that the latter regarded such springs as indicative of volcanic 



