Tertiary Formations of the United States. 307 



chalk formation, containing Belemnites and Exogyrae, occurs between 

 Vance's Ferry and Camden. The Santee limestone, he is of opinion, 

 cannot be less than 120 feet thick at Strawberry Ferry, being verti- 

 cally exposed to the extent of seventy feet in the banks and bottom 

 of Cooper river, and to the height of fifty feet in the neighbouring 

 hills. Its upper surface is very irregular, and is usually covered with 

 sand in which no shells have been found. Mr. Lyell followed 

 the limestone north-westwardly for twelve miles by Cave Hall and 

 Struble's Mill to near Half-way Swamp. At Stoudenmire or Stout 

 Creek, a tributary of the Santee, it has disappeared beneath a newer 

 tertiary deposit of considerable thickness, consisting of slaty clays, 

 quartzose sand, loam of a brick-red colour, and beds of siliceous burr- 

 stone. Mr. Lyell is not aware of any published description of this 

 formation, though he afterwards met with it on the Savannah river. 

 In both localities some of the clays break with a conchoidal flinty 

 fracture when dry, and even occasionally pass into a stone closely re- 

 sembling menilite. The fossils which he found were in the state of 

 casts. He does not determine whether this formation should be re- 

 garded as an upper division of the eocene group or not ; but he has 

 little doubt that it is of the same age as the burr-stone series of 

 Georgia. In the notice of the cretaceous and tertiary strata of the 

 Southern states, drawn up by Dr. Morton from the notes of Mr. Va- 

 nuxem, the tertiary limestone and the burr-stone sand and clay are 

 included in the same group, and Mr. Vanuxem informed Mr. Lyell 

 that he had not been able to determine their relative position ; but 

 from what Mr. Lyell saw on the Savannah river, he infers that the 

 burr-stone formation is above the limestone. One of the strata at 

 Stoudenmire is extremely light and of white colour and resembles 

 calcareous tufa, but according to the analysis of Prof. Shepard it con- 

 tains no carbonate of lime ; Mr. Lyell, therefore, states it may pro- 

 bably be of infusorial origin. 



At Aikin, sixty miles west of Orangeburg, and near the left bank 

 of the Savannah, an inclined plane in a railway has been cut through 

 strata 160 feet in thickness, consisting of earth and sand of a vermi- 

 lion colour and containing much oxide of iron ; also of mottled clays 

 and white quartzose sand with masses of pure white kaolin. These 

 strata are within ten miles of the junction of the tertiary formation 

 and the great hypogene region of the Appalachian or Alleghany 

 chain, and their materials, Mr. Lyell states, have evidently been de- 

 rived from the decomposition of clay-slate and granitic rocks. No 

 fossils were observed by him in the deposit at Aikin. A similar for- 

 mation is extensively developed at Augusta, where the Savannah di- 

 vides the states of South Carolina and Georgia, and it must, in some 

 places, be more than 200 feet thick. Three miles above the town are 

 the rapids, which descend over highly inclined clay-slate and chlorite 

 schist, overlaid unconformably by tertiary beds. This point is the west- 

 ern boundary of the supracretaceous series ; and Mr. Lyell observes, 

 that on all the great rivers of the Atlantic border from Maryland to 

 Georgia, and still further south, the first falls or rapids are along aline 

 at which the granitic and hypogene rocks meet the tertiary, and which 



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