AMERICAN GEOLOGY DECADE OF 1850 L859. 4 ( .»H 



marginal forest growth might be uprooted and as the sea again 

 retreated the material would be spread broadcast and mixed with 

 coarse rock detritus. When finally the earthquake paroxysms ceased 

 and the sea became quiet, the fine silt in suspension was deposited, 

 forming thus the soil for another growth. 



The regular decrease in the amount of volatile bituminous matter in 

 the coal as one passes from west to east was accredited to the action 

 of the— 



prodigious quantity of intensely heated steam ami gaseous matter emitted through 

 the crust of the earth, by the almost infinite number of cracks and crevices which 

 must have been produced during the undulation and permanent bending of the strata. 

 The coal in the east basin would thus be effectually steamed, and raised in tempera- 

 ture in every part of the mass would discharge its bituminous matter in proportion 

 to the energy of the disturbance. 



Rogers, it should be noted, found in the American Carboniferous no 

 recognizable base defined by organic remains alone, and in his classifi- 

 cation relied mainly on the suddenness of the change from marine to 

 terrestrial forms and the rapid appearance of that amazing vegetation 

 characteristic of the coal period. 



He conceived the Connecticut red sandstone ;b having been depos- 

 ited on sloping shores within a narrow estuary, its greatest depth near 

 its eastern margin, the material itself having been derived from the 

 west. The sandstone west of the Hudson in New York State he 

 believed to have been deposited in an estuary having its greatest depth 

 to the northwest, the materials being derived from the southeast. 

 The period, he argued, was ushered in by a sudden agitation of the 

 region, resulting in an abrupt depression of the tidal portions of each 

 tract below the general ocean level. Into these depressions the sud- 

 denly displaced drainage would drop a lot of fragmentary material 

 such as would form the lower lying conglomerates. Finer materials 

 brought in later by stream action, and more or less modified by tides, 

 formed the upper beds. He agreed with Emmons in regarding these 

 Mesozoic sands as of Jurassic and Oolitic age. 



One of the most important chapters in the work related to types of 

 orographic structure and the physical structure of the Appalachian 

 chain, which was worked out in conjunction with his brother. Prof. 

 William B. Rogers. This formed the substance of a paper read 

 before the Association of American Geologists at its third session in 

 April, 1842, and already noted under that date (see p. M7<»). It is 

 well to recall, however, that, under the title of Dislocation of <tn 

 Anticlinal Axis Plant — Uninverted Sid, of War, Shoved Over the 

 Inverted, he described and illustrated the overthrust faults of the 

 modern geologist, and remarked on their misleading character, owing to 

 the resulting dipping of younger strata beneath those which are older. 



The origin of valleys occupying the crests of anticlinal ridges, which 

 he designated as ''valleys of elevation," he rightly described as due to 



