Foerste — Eocene and Miocene of Georgia and Florida. 53 



Chattahoochee bed and the Aspallaga clays, and would sug- 

 gest that the brecciated limestone just below either represents 

 a second horizon of brecciation, or that there must once have 

 been a great Eocene island in this part of the country and that 

 at the Griffin Creek locality the elevation was such that there 

 was still a chance for shore work, at a time just preceding the 

 deposition of the two beds of later age at that locality. 



The elevation at Griffin's Creek is 180 feet above the sea ; 

 at Glenn's Well, 2J miles southward, the base of the Chatta- 

 hoochee is 102 feet above the sea level. This would give the 

 Griffin bed at this point an elevation of 80 feet above the base 

 of the Chattahoochee, instead of 130 feet, as given in the Flint 

 River section. This may possibly indicate a thinning out of 

 the Chattahoochee section towards the eastward. 



Powell's limesink lies 7 miles east of Bainbridge. The 

 elevation of the base of the Chattahoochee is there 155 feet 

 above the sea level. So little has yet been done to trace out 

 anticlinal axes, strikes and dips of these flat-lying rocks that it 

 would be difficult to affirm much from known data. The 

 more northern location of this locality and a low westward as 

 well as southern dip might account in part for its greater eleva- 

 tion above sea level. Bat the belief in an uneven base of the 

 Chattahoochee seemed the most natural at the time field ob- 

 servations were still being made.* 



The Aspallaga clays, not seen by us at the type locality, are 

 well exposed at Rock Bluff. According to Dall and Stanley 

 Brownf the marl has here a thickness of 67 feet. Rock Bluff 

 representing a southing of about four and a third miles from 

 Aspallaga Bluff, the base of the Aspallaga clays being 50 feet 

 above the river at Aspallaga Bluff, f and 12 feet above at Rock 

 Bluff, f the dip of the rocks may be variously estimated at 

 from 9 to 11 feet per mile southwards, according to the sup- 

 posed fall in the river level. Alum Bluff lies about 6-J miles 

 south of Rock Bluff, measuring across the supposed strike of 

 the Miocene. At this rate it seems as though the Aspallaga 

 clays must thin out more or less southwards, since otherwise 

 they should be at about water level or slightly above, at Alum 

 Bluff. No doubt they occur at no great distance below water 

 level. At this rate the Chipola bed must be rather thin. Its 

 base may be estimated as occupying a position at least 160 

 feet above the level of the base of the Chattahoochee as shown 

 at Wiley's Landing. The question as to whether the Aspal- 

 laga clays belong in the Chattahoochee or in the Chipola will 

 no doubt be settled as investigations go on. The Anomia in 

 these clays was found in the Wiley's Landing basal Chatta- 

 hoochee, as well as at the Griffins' Creek locality, but was not 



* p. 447. f Cenozoic Geology along the Appalachicola Eiver, p. 155. 



