GEOLOGYo 207 



tended to obliterate the presumed line of demarcation between the Carbon- 

 iferous and overlying Permian strata, wherever the transition beds arc most 

 completely developed. 



As regards the passage from the Devonian to the Carboniferous series, 

 Professor Rogers remarked that the observations of Mr. White on the Bur- 

 lington strata had their counterpart in those of Griffith, Jukes, McCoy, and 

 other Irish geologists, who have been led to include in the lower Carbon- 

 iferous series of Ireland a thick group of deposits which Murchison and 

 others place in the Devonian. Indeed, according to McCoy's determinations, 

 the Carboniferous limestone of Ireland contains among its fossils quite a 

 number of forms identical with those of the Devonian rocks, as well as 

 many that belong also to the Upper Silurian. 



These facts and considerations lend support to the view that the changes 

 of fossil faunas are more gradual in proportion to the degree in which the 

 successive deposits of a given period have been preserved from destruction, 

 and certainly favor the doctrine of a gradational continuity in the succession 

 of living races rather than that of sudden underived creations. 



Looking to the question of the equivalency in time of the rocks described 

 in Mr. AVhite's paper with deposits in the eastern and southeastern parts of 

 the Appalachian basin, we are struck with the enormous thickness of the 

 several groups of strata in the latter region, which find a representation, as to 

 period, in the inconsiderable mass of calcareous and other beds, occupying, in 

 this western locality, the interval between rocks of unequivocally Devonian 

 and Carboniferous ages. In this part of the Appalachian area, the interval 

 referred to includes not only the vast thickness of red and variegated strata 

 of the Ponent or Catskill series, but in Pennsylvania and Virginia a great 

 mass of conglomerate, sandstone, and shale, containing in some districts 

 considerable seams of coal, the whole attaining in places an aggregate thick- 

 ness of more than six thousand feet. This latter, or Vespertine series, 

 maintaining a position always below the shales and limestones charged 

 with Archimedes (Fenestella) Pentreinites, and other carboniferous limestone 

 fossils, and forming a lower carboniferous group corresponding to that of 

 Scotland and JSTova Scotia, may perhaps claim a place on the same time- 

 level with the portion of the Burlington group in which the carboniferous 

 forms have assumed predominance, or may extend in period as far as the 

 lower Archimedes or Keokuk limestone. 



But all such attempts at synchronizing distant deposits must be limited to 

 a general and vague result. Even when corresponding fossils would seem 

 to mark a simultaneous origin, we must not forget the large agency of 

 migration, and the long lapse of years which in many cases may have been 

 required for the extension of a living race into distant submarine settle- 

 ments. 



ON THE SYNCHRONISM OF THE COAL-BEDS OF NEW ENGLAND 



AND THE WESTERN STATES. 



The following paper was read at the American Association, 1800, by 

 Professor C. H. Hitchcock, of Amherst, Mass. : 



A few years ago, no one thought it possible to identify any particular bed, 

 or scries of beds, of coal in the carboniferous system by means of peculiar or 

 characteristic fossils. But now, thanks to several observers and collectors, 

 chief of whom is Leo Lesquereux, of Columbus, Ohio, most of the beds of 



