44 FOURTH REPORT — 1834. 



Conrad,) occurs at the Eutaw springs and at Nelson's Ferry on 

 the Santee river, but it lies in a white limestone, associated with 

 very different fossils from those which accompany this Ostrea at 

 Claiborne. This limestone is doubtless analogous to that on 

 which the tertiary of Claiborne is based, but its true character 

 is given by Dr. Morton, in his Synopsis, now in the press. Eocene 

 deposits commence in Maryland, and extending in a south-west 

 direction, crop out at intervals in the States of Virginia (?) and 

 North and South Carolina, and are always of very inconsiderable 

 breadth. They meet the Savannah river at Shell BluflF, fifteen 

 miles below Augusta, and appear at Silver Bluff and other 

 places, occupying a space of about forty miles, following the 

 course of the same river. According to Mr. Vanuxem, Shell 

 Bluff is about " seventy feet high, formed of various beds of im- 

 pure carbonate of lime, of comminuted shells, and having at its 

 upper part the Ostrea gigantea ? in a bed nearly six feet in 

 thickness." 



The eocene formation appears on the Oconee, below Mill- 

 edgeville, judging from a few fossils which have been sent from 

 that vicinity. The matrix is calcareous, whitish, and very fri- 

 able. We know nothing of its appearance on Ocmulgee and 

 Fhnt rivers, but it has been observed in various parts of Early 

 county, and it occurs at Fort Gaines on the Chattahooche, where 

 it constitutes a bluff from 150 to 200 feet in height, which has 

 a close resemblance to that at Claiborne. Its extent on the 

 river is about one mile. 



In Georgia it is common to find the fossiliferous beds of the 

 eocene developed as a pure siliceous rock or Buhr stone. The 

 calcareous and other matter originally in the rock has all disap- 

 peared and been replaced by silica, preserving, however, the 

 casts of shells so perfectly that they may often be readily recog- 

 nised. 



The eocene next appears in Wilcox county, Alabama, in the 

 state of a hard dark-coloured sandstone, containing the charac- 

 teristic shells, which are not mineralized at all, but are chalky 

 and imperfect. This formation only extends eight or nine miles 

 along the Alabama river. Claiborne Bluff is about one mile in 

 loigth : a similar bluff, of equal extent, occurs three miles below, 

 and about three or four miles south of this the deposit termi- 

 nates in a bluff of less elevation. Here the upper bed is charac- 

 terized by Scntella Lyelli (Conrad), the stratum being about 

 three feet in thickness, with a matrix of angular quartzose sand, 

 tinged by oxide of iron. Nearly the whole country in the vi- 

 cinity of Claiborne is secondary, the eocene having been traced 

 only about one mile east of the village, in the banks of a small 



