186 APPENDIX. 



G. — Page loo. 



" The whole period during which the Mississippi has transported its earthy burthen to the 

 ocean, though perhaps far exceeding a hundred thousand years, must be insignificant in a geo- 

 logical point of view, since the bluffs or cliffs bounding the great vaUey (and there/ore older in 

 date), and which are from fifty to two hundred and fifty feet in perpendicular height, consist in a 

 great part of loam, containing land, fluviatile, and lacustrine shells of species stiU inhabiting the 

 same country. These fossil shells, occurring in a deposit resembling the loess of the Rhine, are 

 associated with the bones of the mastodon, elephant, tapir, mylodon, and other megatheroid ani- 

 mals ; also a species of horse, ox, and other mammalia, most of them of extinct species. The 

 loam rests, at Vicksburg and other places, on eocene or lower tertiary strata, which, in their turn, 

 repose on cretaceous rocks. A section from Vicksburg to Darien, through the States of Missis- 

 sippi, Alabama, and Georgia, exhibits this superposition, as well as that of the cretaceous strata, 

 on carboniferous rocks at Tuscaloosa. Sir Charles Lyell ascertained, that the huge fossil ceta- 

 cean, named Zeuglodon by Owen, is confined to the eocene deposits. In the cretaceous strata, 

 the remains of the Mososaurus and other reptiles occur without any cetacea. The coal-fields 

 of Alabama were next alluded to, from which fossil plants have been procured by Professor 

 Brumby and Sir C. Lyell, of the genera Sphenopteris, Neuropteris, Calamites, Lepidodendron, 

 Sigillaria, Stigmaria, and others, most of them identical in species, as determined by Mr. Charles 

 Bunbury, with fossils of Northumberland. This fact is the more worthy of notice, because the 

 coal of Tuscaloosa, situated in latitude 33° 10' north, is further south than any region in which 

 this ancient fossil flora had previously been studied, whether in Europe or North America ; and 

 it affords, therefore, a new proof of the wide extension of a uniform flora in the carboniferous 

 epoch. Sir Charles, adverting to the opinion recently adopted by several able botanists, that the 

 climate of the coal period was remarkable for its moisture, equability, and freedom from cold, 

 rather than the intensity of its tropical heat, stated that this conclusion, as well as the oscilla- 

 tions of temperature implied by the glacial period, is confirmatory of the theory first advanced 

 by him in 1S30, to explain the ancient geological changes of climate by geographical revolutions 

 in the position of land and sea. 



" The lapse of ages, implied by the distinctness of the fossils of the eocene, cretaceous, car- 

 boniferous, and other strata, is such, that, were we to endeavor to give an idea, of it, we must 

 estimate its duration, not by years, as in the case of the delta, but by such*units as would be 

 constituted by the interval between the beginning of the delta and our own times." — Report of 

 the British Association, 8fC., for 1S46 ; Appendix, p. 118. 



