Walls of North- Carolina. 7 



In the course of their digging they passed through a thick 

 bed of roof slate, of a dark bluish colour. Indeed, this 

 section of country abounds in beautiful slates. Broad veins 

 of it may be found running in various directions from this 

 mountain, chiefly South-West ; it is slightly inclined to the 

 North. Some cross the river, and run through the country 

 to a considerable extent. 



No lime-stone has been found in this county, except a 

 small quantity of the species called Tufa, specimen No. 8, 

 which I discovered in the neighbourhood of Salisbury. I 

 likewise send you some petrifactions of shells, found in great 

 abundance on the plantation of the Hon. William C, Love, 

 near Knoxville, East Tennessee, and presented to me by 

 him. You have doubtless received many from that coun- 

 try before; but one of them is to my view of so curious an 

 appearance, that I cannot withhold it (see No. 9). If we 

 did not know that the species of fungi called toad-stool, are 

 subject to such rapid decay as to render them improbable 

 subjects for this process, I should strongly suspect it was 

 one of them. 



In this rapid sketch, I fear I have but very imperfectly 

 answered your queries. If however, the information con- 

 tained in it should contribute to settle the once violently agi- 

 tated question concerning the nature of these walls, and cor- 

 rect the erroneous opinions entertained by many respecting 

 them, it may not be wholly useless. Should you think 

 proper so to arrange and dispose these materials, as to an- 

 swer this or any other purpose, they are perfectly at your 

 service. With the highest respect 



for your literary and private character, 

 I am, dear Sir, your most ob't serv't, 



JNO. BECKWITH. 

 Saml. L. Mitchell, M. D. 



President of the Keiu-Yorh Lyceum of JYatural History. 



