MARL FROM ASHLEY RIVER, S. C. 



The composition of this marl is remarkable for the large 

 amount of phosphoric acid contained in it. The epoch to 

 which this formation of marl is referable is not yet fully de- 

 cided, but it probably consists of beds of different ages, the 

 newest being as old as the eocene of Yirginia and Maryland. 

 It has been explored to the depth of three hundred and nine 

 feet in boring a well. Specimens from depths varying from 

 one hundred and ten to three hundred and nine feet have been 

 sent to Prof. Bailey, of West Point, who has already subjected 

 them to microscopic examination, and a short account of his 

 results will be found in the accompanying note.* A fuller 



* Extract of a Letter from, Prof. Bailey to J. L. Smith. — "Charleston is 

 built upon a bed of animalcules several hundred feet in thickness, every 

 cubic inch of which is filled with myriads of perfectly preserved microscopic 

 shells. These shells, however, do not, like those beneath Eichmond and 

 Petersburg, etc., belong to the siliceous infusoria, but are all derived from 

 those minute calcareous-shelled creatures called by Ehrenberg polythalamia, 

 and by D'Orbigny the foraminifera. You are aware that Ehrenberg proved 

 chalk to be chiefly made up of such shells; and you will doubtless be pleased 

 to learn that the tertiary beds beneath your city are filled with more numerous 

 and more perfect specimens of these beautiful forms than I have ever seen in 

 chalk or marl from any other locality. The following are some of the results 

 I have obtained: 



" 1. The marls from the depth of one hundred and ten to one hundred 

 and ninety-three feet are certainly tertiary deposits, for I have found them 

 to contain polythalamia of the family plicatilia of Ehrenberg (agathestegens 

 of D'Orbigny), which family, as far as is yet known, occurs in no formation 

 older than the tertiary. 



" 2. The beds from the depth of one hundred and ninety-three to three 

 hundred and nine feet contain so many species in common with the beds 

 above them, that although I have not yet detected the plicatilia, I yet be- 

 lieve they must also belong to the tertiary formation. 



" 3. The forms found in these beds agree much better with those detected 

 by me in the eocene marls from Panumkey Kiver, Va., than they do with 

 miocene polythalamia from Petersburg, Va., and I am consequently inclined 

 to believe that they belong to the eocene epoch. 



