40 GEOLOGICAL STRUCTURE OF THE 



lime-stone of the environs of Paris, and mill-stone* 

 have been made of it, but are found to be softer than 

 those of France, In its seams have also been dis- 

 covered depositions of hyalite, or the concretionary 

 hyaline quartz of Hauy, 



At Nelson's Ferry, on the south side of the San- 

 tee, J again observed an horizontal ledge of the floetz 

 lime-stone, of a whitish color, and fragile consistence, 

 containing amidst innumerable masses of small shells, 

 those of some Ostrea, not very dissimilar to existing 

 species, but of a remarkable thickness, and occasion- 

 ally impressed with the forms of other shells. The 

 copious and clear springs of this formation continue 

 to within ten miles of the city of Charleston, where, 

 with its overlay of ferruginous sand-stone, it forms 

 the foundation of all the other alluvial deposits. 

 Amorphous carbonaceous remains, connected pro- 

 bably with lignite, sparingly appear in this soft 

 sand-stone a few miles from Charleston, In a for- 

 mer route, from Savannah and Augusta, in Georgia, 

 I repeatedly met with this calcareous bed, in which 

 even occurs the trilobites paradoxus, and the ovate 

 encrinal fossil, figured by Parkinson and described 

 by Mr. Say in Silliman's Journal, under the 

 name of Pentremiie, hitherto found only in North 

 America, and in connection probably with this for- 

 mation,* In some parts of South Carolina, this 

 calcareous- rock appears of a friable texture, and 



* This curious fossil occurs also, abundantly in the licie- 

 Houe of Huntsville, in the Mississippi territory. 



