178 Association of American Geologists and Naturalists. 



axes ; increasing interval between the axes as we advance towards the 

 northwest. 



5th. Descriptions of a series of sections across the chain, with a 

 table of the northwest and southeast dips which they disclose. 



Part II, treats of the following theoretical topics : 



1st. The force producing the flexure and elevation of the strata, 

 was compounded of a wave-like oscillation of the crust, and a tangen- 

 tial pressure towards the northwest. 



2nd. Theory of the origin of the supposed subterranean undula- 

 tions, and of the manner in which the strata became permanently bent. 



3rd. Identity of the undulations of the crust with the wave-like mo- 

 tion of the earth in earthquakes. This latter shown to result from an 

 actual billowy oscillation of the surface of the subterranean fluid lava. 



4th. 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. Henri/ 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; (J,) rocks 

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

 tribution ; inferences respecting the position of the ancient carbonifer- 

 ous 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 mo- 

 tion of the waters, the under clay on the contrary a quiet subsidence of 

 sediment. 



