39 



Atlantic there is a wide extent of nearly horizontal tertiary strata, 

 which at the*base of the mountains are 500 feet and upwards in 

 height, but decline in level nearer the ocean and at length give place to 

 sandy plains and low islands skirting the coast, in which strata con- 

 taining marine shells of recent species are met with, slightly eleva- 

 ted above the sea. Occasionally dei)osits formed in freshwater 

 swamps occur, below the mean level of the Atlantic or over- 

 flowed at high tide. In this district Mr. Nuttall discovered, on the 

 Neuse 15 miles below Newburn, in South Carolina, a large assemblage 

 of mammalian bones, including those of the Mastodon giganteum, rest- 

 ing on a deposit containing m.arine shells of recent species. Mr. 

 Conrad presented Mr. Lyell with the tooth of a horse covered with 

 barnacles, from this locality. Professor Owen has examined it and 

 could find no corresponding tooth of a recent species, but considers 

 it as agreeing with the horse-tooth brought by Mr. Darwin from the 

 north side of the Plata in Entre Rios in South America. 



South Carolina. — Remains of the Mastodon were found in dig- 

 ging the Santee Canal, in a spot where large quadrupeds might now 

 sink into the soft boggy ground. 



Georgia. — Bones of the Mastodon and Megatherium occur in 

 this district in swamps formed upon a marine sand containing shells, 

 of species now inhabiting the neighbouring sea. 



Mr. Lyell in conclusion offers the following observations : — • 



1. That the extinct animals of Bigbone Lick and those of the At- 

 lantic border in the Caroiinas and in Georgia belong to the same 

 group, the identical species of Mastodon and elephant being in both 

 cases associated with the horse, and while we have the Mylodon and 

 Megatherium in Georgia, the Megalonyx is stated by several authors 

 to have been found at Bigbone Lick. 



2. On both sides of the Appalachian chain, the fossil shells,, 

 whether land or freshwater, accompanying the bones of Mastodons, 

 agree with species of Mollusca now inhabiting the same regions. 



3. Under similar circumstances Mr. Darwin found the Mastodon 

 and horse in Entre Rios, near the Plata, and the Megatherium, Me- 

 galonyx and Mylodon, together with the horse, in Bahia Blanca in 

 Patagonia ; these South American remains being shown by their 

 geological position to be of later date than certain marine Newer 

 Pliocene, and Post-pliocene strata. Mr. Darwin also ascertained 

 that some extinct animals of the same group are more modern in 

 Patagonia than the drift with erratics. 



4. The extinct quadrupeds before alluded to in the United States 

 lived after the deposition of the northern drift, and consequently the 

 coldness of climate which probably coincided in date with the trans- 

 portation of the drift, was not as some pretend the cause of their 

 extinction. 



