321 



As regards the passage from the Devonian to the Carbonif- 

 erous series, Prof. Rogers remarked that the observations of 

 Mr. White on the Burlington strata had their counterpart in 

 those of Griffith, Jukes, McCoy, and other Irish geologists, who 

 have been led to include in the lower Carboniferous series of Ire- 

 land 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 faunae 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. White'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 in- 

 considerable 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 Appala- 

 chian 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 con- 

 glomerate, sandstone, and shale, containing in some districts con- 

 siderable seams of coal, the whole attaining in places an aggre- 

 gate thickness of more than six thousand feet. This latter, or 

 Vespertine series, maintaining a position always below the shales 

 and limestones charged with Archimedes {Fenestelld) Pentremites, 

 and other carboniferous limestone fossils, and forming a lower 

 carboniferous group corresponding to that of Scotland and Nova 

 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 he 



PROCEEDINGS B. S. N. H. VOL. VII. 21 SEPTEMBER, 1860. 



