154 DALL AND STANLEY-BROWN — APALACHICOLA RIVER GEOLOGY. 



found by Dr Foerste at a height estimated at 130 feet above the water, 

 but this was doubtless transported in some way from below. At the 

 highest point of the blufi', where this limestone showed the thickest 

 exposure, about 40 feet were visible and ten feet more probably con- 

 cealed, by talus and water. Above it lies about 20 feet of bluish green 

 marl, conformable to the limestone, and much of which is unfossil- 

 iferous. In places, however, there are layers of small oyster-shells and 

 a Pecten which has somewhat the appearance of a young Pecten madi- 

 sonius, and has been mistaken for that species. It is, however, a Chipola 

 species, and may prove new. This marl was observed by Mr Jussen, 

 whose manuscript section we confirmed on the spot ; it is what Mr. John- 

 son has called^ the "Aspalaga clays," assigning it a thickness of 60 feet ; 

 but his section is evidently too much generalized, and the bed did not 

 exceed 20 feet in thickness at any point where we Avere able to observe 

 it. Mr Johnson's heights were measured with a pocket aneroid and 

 seem excessive ; that method of measurement, without careful correc- 

 tion and comparison, being but little to be relied upon. 



Above the marl at the edge of the bluff, omitting talus, there appeared 

 to be about 5 feet of reddish clay and gravel, but further back this thick- 

 ness is very greatly surpassed, and may reach 40 or 50 feet. On account 

 of the manner in which the upper part of the hill is weathered and over- 

 grown, a large amount of time and labor would have been required to 

 expose and verify a complete section. We therefore confined our work 

 to the verification of the actual section facing the river.- 



It is to be mentioned that in Mr Langdon's paper, previously alluded 

 to, he gives a section at a point which he calls " Ocheesee," which subse- 

 quent observers have not identified, but which Mr Johnson suggests may 

 be the same as Aspalaga bluff, which is not mentioned by Mr Langdon. 

 The discrepancy in height and stratigraphy forbids us to accept this 

 identification; and, indeed, we did not observe any place where the 

 strata clearly recalled those mentioned in Langdon's section. At the 

 present Ocheesee landing the bank is wholly of alluvial material, and is 

 on the opposite side of the river, so Mr Langdon's section could not have 

 been made there. 



Section at Aspalaga Bluff. 



Superficial sand, mostly absent at river. feet. 



Reddish sands and gravel, with streaks of clay 5 



Bluish-green clayey marl, with Ostrea and Pecten 20 



Chattahoochee limestone, hard and soft layers 40 



Talus to water (probably Chattahoochee) 10 



Total thickness above water 75 



*Bull. Geol. Soc. Am., vol. 3, 1891, p. 129. 



