MARL FROM ASHLEY RIVER, S. C. 173 



detail may be expected from him at some future time; and 

 when it does come it will no doubt be a rich feast for the 

 naturalist of this country, prepared, as it will be, by a skillful 

 hand. 



Organic remains are quite abundant in this marl, although 

 in an imperfect state. Its composition is somewhat peculiar, 

 and a knowledge of it may be of some general importance. 

 It varies in the proportion of its ingredients, but seems to 

 be constant as regards their character. From among several 

 analyses the following is selected as being an average one : 



Carbonate of lime 65.8 



Carbonate of magnesia 2.4 



Silica 15.6 



Alumina 10.0 



Phosphate of lime with a small quantity of phosphate 



of magnesia 5.0 



Phosphate of iron. 



Fluoride of calcium.. 



Crenate of iron 



Crenate of lime 



Ammonia 



Organic matter 



1.2 



" 4. All the marls to the depth of two hundred and thirty-six feet present 

 the polythalamia in vast abundance, and in a state of surprising preservation. 

 The most delicate markings of the shells are perfectly preserved, and some 

 of the forms are so large that they may be easily seen with a common 

 pocket-lens. 



" 5. The lithological characters of the marls from two hundred and thirty- 

 six to three hundred and nine feet differ from those above ; and although the 

 polythalamia are still abundant, and many of the species appear to be the 

 same as in the strata above, yet they are less easy to observe on account of the 

 greater compactness of the marls, and the adherence of crystalline calcareous 

 particles to the shells. 



"6. The marls which you sent from the Cooper Eiver, thirty-five to thirty- 

 eight miles above Charleston, also abound in polythalamia; and so many of 

 the species are identical with those found beneath Charleston that they most 

 probably belong to the same formation. This place on the Cooper Eiver 

 may be the outcrop of the very slightly-inclined beds which exist under 

 Charleston. [In this conclusion Prof. Bailey is correct. — J. L. S.] 



"7. The polythalamia, to whose labors South Carolina owes so large a 

 portion of her territory, are still at work in countless thousands upon her 

 coasts, filling up harbors, forming shoals, and depositing their shells to record 

 the present state of the sea-shore, as their predecessors, now entombed be- 

 neath Charleston, have done with regard to ancient oceans. The mud from 

 Charleston harbor is filled not only with beautiful polythalamian shells, but 

 is also very rich in siliceous infusoria." 



