2IO FLORIDA GEOLOGICAL SURVEY SIXTH ANNUAL REPORT. 



3. APALACHICOLA RIVER BLUFFS AND BOTTOMS. 



(figures 49-51) 



References. Chapman, Croom, Dall & Stanley-Brown, Gray, Harper i 

 (216, 234-235), Harper 5 (225-226), Matson & Clapp (78-84, 96-97, 145), 

 Matson & Sanford (95-101, 112-113), Nash (96-97, 103) Sellards & Gunter 

 I (261-277, 285-286), and U. S. soil survey of Gadsden Co. (by Fippin and 

 Root, 1904). Illustrated in 2nd Ann. Rep., pi. i, 17; 3d, pi. 19.1; 4th, pi. 

 II. I, fig. II. 



From its beginning at the southwestern corner of Georgia to 

 about the latitude of Bristol the Apaiachicola River has on its east 

 side some of the highest land in Florida (a part of the pme hill 

 region described farther on), which comes out to the river in several 

 places, making steep bluffs. Between these bluffs are deep rich 

 \alleys, some of which extend several miles back from the river. 

 The bluff region is too narrow for its area to be estimated accurate- 

 ly, but it probably covers less than 50 square miles in this state. It 

 continues northeastward into Georgia, soon diverging from the 

 Flint River and becoming less prominent, but as the boundary be- 

 tween the lime-sink region and the pine hills (Altamaha Grit region) 

 it can be traced nearly across that state, where it forms a typical in- 

 land-facing escarpment, or ciicsta."^ 



Geology and Soils — 'The underlying rocks of this region, well 

 exposed on the river bluffs and along some of the creeks, mostly be- 

 long to the Chattahoochee and Alum Bluff formations (Upper 

 Ohgocene). Lithologically the strata vary from argillaceous lime- 

 stone and marl to fuller's earth, clay and sand. There seems to be no 

 limestone pure enough to form caves, though there are some lime- 

 sinks near the state line. Much of the soil is derived from the weath- 

 ering of these Tertiary rocks, and is quite fertile. In the more level 

 places there is also considerable sand and sandy loam, which may 

 represent the Lafayette and other comparatively recent formations. 

 Humus is quite abundant, for reasons which will be evident. Be- 

 tween the hills and the river there are alluvial bottoms of varying 

 width, with very fertile soil, as is usual in such places. 



Topography and Hydrography — This region occupies a slope 

 from the high pine land on its eastern border, 200 to 300 feet above 

 sea level, to the river, which in this latitude is something like 50 

 feet above sea level at low water. Aspalaga Bluff, in Gadsden Coun- 



*For notes on this escarpment in Georgia, see Bull. Torrey Bot. Club 

 32:144-145, 190S; Ann. N. Y. Acad. Sci. 17:17-18. 1906. 



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