799 
terials might be mistaken for them, if the veins of quartz which often 
traverse the argillaceous beds at a considerable angle, did not con- 
tinue unaltered. «The only point:at which: Mr. Lyell saw any organic 
remains in beds associated with these upper tertiary red strata was 
at Richmond in Virginia, where he obtained casts: of decidedly mio- 
cene fossils ; but as he observed:on the Savannah river thick beds of 
sandy-red earth beneath the burr-stone of Stony Buff, he concludes 
that the same mineral character may sometimes belong to the upper 
division of the eocene group... At the rocks six miles west of Augusta, 
the tertiary beds derived from the hypogene rocks have the: appear- 
ance of granite, and have been called gneiss by some geologists. 
They exhibit occasionally’ a distinct cross-stratification, and include 
angular masses of pure kaolin. 
Though the Savannah, in its course from Augusta to the sea, flows 
for the greater part in a wide alluvial plain, and: has a fall of less 
than one foot in a mile, yet Mr. Lyell descended it to obtain infor- 
mation, by means of the Bluffs, respecting the superposition of the 
several masses, natural sections being otherwise difficult to obtain. 
After passing cliffs of horizontal strata in which the brick-red sand 
and loam prevail, the first exposure of a new deposit was observed 
at Shell Bluff, forty miles below Augusta. The height of the section 
was 120 feet, and its extent more than half a mile. . The lowest ex- 
posed strata consisted of white, highly calcareous sand, derived chiefly 
from comminuted shells, but the beds: passed upwards into a solid 
limestone, sometimes concretionary, and containing numerous casts 
of shells. -In one place a layer of pale green clay showed the hori- 
zontal character of the formation. The upper part of this deposit is 
more sandy and clayey, and incloses a bed of huge oysters, Ostrea 
Georgiana, occupying evidently the position in which they. lived. 
The total thickness of these lower strata is eighty feet. The upper 
portion of the cliff is composed of forty feet of the red loam which 
prevails at Aikin and Augusta, and yellow sand. Mr. Lyell did not 
find any fossils in this deposit, but he believes that it belongs to 
the burr-stone formation, and therefore to be an upper eocene accu- 
mulation. At his first inspection of the casts contained in the lime- 
stone, he inferred that they belonged to eocene species, without any 
intermixture of cretaceous or miocene forms; butiit was not till he 
had the advantage of Mr. Conrad's assistance that he was able to de- 
termine the following twelve species which are well known to be cha- 
racteristic fossils of the eocene beds of Claiborne and Alabama :— 
Oliva Alabamiensis. Corbula nasuta. 
Calyptrea trochiformis. pene OMISCUS: 
‘Dentalium alternans. Nucula magnifica. 
Venericardia planicosta. Crassatella pretexta. 
Cytherea Poulsoni. Ostrea selleformis. 
—— peroyata. — Alabamiensis. 
‘ The same shelly, white, calcareous beds, overlaid by red clay andloam, 
are exhibited at London Bluff, nine miles below Shell Bluff, and a ho- ° 
rizontal bed of the large oysters is exposed in/a cliff two miles farther 
