150 DALL AND STANLEY-BROWN — APALACHICOLA RIVER GEOLOGY. 



Its correlation with the proper horizon in the Alum bluff section was 

 necessary to a right understanding of the geology over a considerable 

 area. Finally, the sections hitherto made had not been precisely located 

 or exactly measured, part of the discrepancies alluded to doubtless 

 arising from examination of the beds at different instead of identical 

 points. 



The season chosen for our work was that of the river's lowest stage, 

 which, owing to drouth, was, as we were assured by old lumbermen, 

 within two or three feet of the lowest water known to them. 



It should be noted in passing that the identification of the various 

 bluffs and landings is not easy unless one has an experienced river- 

 man as guide, and in view of the fact that the maps are often incorrect, 

 that changes in the location of landings and even of towns are made 

 with great facility, and that places formerly occupied are now deserted, 

 it is not surprising that travelers are misled as to local nomenclature. 



Area studied. 



In making the investigations upon which this paper is based, the fol- 

 lowing plan * was adopted : We proceeded by rail via Atlanta, Macon 

 and Thomasville to Bainbridge, the head of navigation on the Flint 

 river, Decatur county, Georgia. There we procured two rowboats and 

 floated down the Flint river to its junction with the Apalachicola at the 

 Florida boundary, and thence down the latter river to Blountstown, Cal- 

 houn county, Florida, below which the low swamps of the coastal plain 

 begin. This plan made it possible to camp at localities where investiga- 

 tions were to be made, and also to make such excursions inland from 

 the river as were deemed desirable. The points visited are enumerated 

 in the detailed statements presented later. 



Descending the Flint river, the rocks, which belong to the Vicksburg 

 series of the Eocene, characteristically distinguished by the presence of 

 Orbitoides mantelli and Pecten poulsoni and perplanus, appear above the 

 water at intervals only, and are separated by low areas where the red 

 beds and alluvial mud alone rise above the river. The higher land ex- 

 hibits the character of gentle, anticlinal folds through which the river 

 cuts its way, forming bluffs which afford in most cases very good natural 

 sections. The land at the river is usually somewhat lower than can be 

 found a few miles away on either side, even at the bluffs, but owing to 

 the thick mantle of gravel and rather dense undergrowth these more 

 distant hills afford" no convenient exposures. The number of parallel 



*For most valuable suggestions and assistance we are especially indebted to Professor R. Pum- 

 pelly, Major T. B. Brooks, Professor E. A. Smith, State Geologist of Alabama; Mr Dubois and Mr 

 R. A. Lytle of Bainbridge, Georgia ; Mr Frank Burns and Mr Wood of Blountstown, Florida. 



