LYELL ON THE EOCENE BEDS OF NORTH AMERICA. 435 



Burrstone Formation. 



I have before mentioned that the white limestone of the Santee 

 River, on being traced in a north-westerly direction, disappeared 

 at Stoudenmire Creek, a tributary of the Santee, beneath a newer 

 deposit of considerable thickness. The latter consists of slaty 

 clays, quartzose sand, loam of a brick-red colour, and beds of sili- 

 ceous burrstone, in some of which fossil sponges, having a coarse 

 fibre, have been detected. Some of the clays break with a con- 

 choidal fracture, and become stony when dried. One of the beds 

 is extremely light, and resembles in appearance some kinds of cal- 

 careous tufa, but does not contain carbonate of lime. I at first 

 supposed it to be of infusorial origin, but some practised observers 

 have been unable with the microscope to discover infusorial cases. 

 There were casts of shells in this rock, and in several of the asso- 

 ciated strata, referable to the genera Cyprcea, Voluta, Natica, 

 Trochus, Corbula, Mactra, Cardita, Cardium, Lucina, JVucula, 

 Pectunculus, Pecten, and Serpula. Among these, a Corbula, Car- 

 dium, and J\ T ticida, seem to agree with Claiborne species ; the rest 

 did not agree with fossils from that locality, nor with those from the 

 miocene beds of Virginia, but I was afterwards shown siliceous casts 

 of Ostrea sellceformis, Cytherea perovata, and other eocene fossils, 

 from strata of the same formation at Orangeburg and near Aikin 

 in South Carolina. I believe, therefore, that the larger portion of 

 the ferruginous sands, red clays, and white beds of kaolin (often 

 miscalled chalk by the inhabitants of South Carolina and Georgia) 

 belong to the Upper Eocene or Burrstone deposit. 



At Aikin, fifteen miles S. E. of Augusta, and near the left bank 

 of the Savannah River, the inclined plane of a railway has been 

 cut through strata, 160 feet in thickness, consisting partly of earth 

 and sand of a vermilion colour, and containing much oxide of iron ; 

 partly also of mottled clays, and white quartzose sand with masses 

 of pure white kaolin. This compact kaolin appears fitted to make 

 good porcelain ware. The globules of iron give a pisolitic ap- 

 pearance to some of the beds of quartzose sand. These beds at 

 Aikin yielded no fossils, but I suppose them to be all referable to 

 the Burrstone or Upper Eocene formation. 



Georgia. 



The same Burrstone formation is continuous from Aikin and 

 Stoudenmire Creek, South Carolina, to Augusta in Georgia, and to 

 the junction of the tertiary with the primary or hypogene rocks 

 above that city. It must attain there in some places a thickness 

 of more than 200 feet, and is very variable in its aspect and com- 

 position. 



At a place called The Rocks, six miles west of Augusta, it con- 

 sists, of a highly micaceous quartzose grit and sand, having much 

 the appearance of certain kinds of granite, and having been by 



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