AMERICAN GEOLOGISTS AND NATURALISTS. 7l 



4tli. Of the geological era of the elevation of the Appalachian 

 chain. 



5th. Analogous phenomena of flexures ; axes in other countries. 



A paper was next read by Prof. Henry D. Rogers, entitled 

 " an Inquiry into the Origin of the Appalachian coal strata, bitu- 

 minous and anthracite." It embraces the following subjects : 



1st. A brief introductory sketch of the researches of other geolo- 

 gists in the same region. 



2nd. The extent and physical features of the Appalachian coal 

 region. 



3rd. The character of the strata ; (a,) rocks of mechanical or ter- 

 restrial origin ; the laws of their gradation and distribution ; (b,) rocks 

 of chemical or marine origin, as limestones, &c.; the law of their dis- 

 tribution; inferences respecting the position of the ancient carbonif- 

 erous sea and its coast 



4th. Of the coal seams, and the phenomena immediately connect- 

 ed with them ; wide range of some of the beds ; identified from basin 

 to basin ; ancient limits of the coal much more extensive ; area of 

 the great Pittsburgh seam, and law of its distribution : present and 

 former areas of the coal strata computed. 



5th. Of the intimate mechanical structure of the coal : inferences : 

 persistency of the- minor subdivisions of the coal beds inconsistent 

 with the doctrine that the vegetable matter was drifted. 



6th. Character of the strata which immediately accompany the 

 beds of coal ; prevailing nature of the under stratum ; Stigmaria ; 

 different composition of the overlying rocks ; these latter indicate a 

 rapid motion of the waters, the under clay on the contrary a quiet 

 subsidence of sediment. 



7th. Beds of marine limestone in contact with the seams of coal. 



8th. Theory of the origin of the coal strata ; sketch of the discov- 

 eries and opinions of preceding writers ; deficiencies in the hypothe- 

 ses hitherto presented ; condition under which the vegetable matter 

 of the coal seams was accumulated ; of the part performed by earth- 

 quake inundations in producing the mechanical strata ; evidences of 

 gradual depressions and risings of the coast of the carboniferous sea ; 

 indications of similar alternations of secular and paroxysmal move- 

 ments of the earth's crust at all geological periods. 



9th. Regular gradation in the proportion of volatile matter in the 

 coal as we cross the Appalachian basins northwestward ; phenomena 

 connected with it; theory of the debituminization of the coal, and 

 conversion into anthracite. 



Prof. W. B. Rogers made a few remarks on Thermal Springs, 

 as relating to the foregoing subject. 



Dr. A. A. Gould, Dr. Amos Binney and Mr. Haldeman, were 

 appointed a committee to report on the geographical distribution 

 of shells. 



