190 Holmes's Notes on the Geology of Charleston. 



present rate of increase, to raise them entirely above the level of 

 the ocean. 



Another important agent in producing the modifications under 

 consideration is the prevailing easterly winds, disposing these 

 sands to be ever shifting from the windward to the leeward, and 

 causing them to move despite all opposition, at a steady though 



almost imperceptible rate. 



At my second visit to the Inlet in the summer of 1846, I ob- 

 served that a -fragment of a ship stranded upon its bar (part of the 

 hood or poop-deck, painted green) had drifted in at high tide and 

 lodged on the Key to the leeward of one of these dunes, the 

 base of which was about thirty feet wide, and at the time I first 

 saw it was being rapidly covered by sands blown over from the 

 windward or ocean side. 



On my second visit in the spring of the following year, I found 

 about three feet of one of the planks of this fragment protruding 

 from the opposite side, the hill or dune having nearly passed over 

 it. How much remained covered, I had no means of ascertain- 

 ing ; the fishermen who frequent the island, had cut up and used 

 the exposed part as fire- wood, thus destroying the ends by which 

 alone I could have formed an estimate. The planks, with the 

 single exception mentioned, were cut even with the sands j and 

 as I had no suitable implement for the removal of the latter, I 

 had to content myself with a superficial examination. 



A similar incident was related to Professor Tuomey and myself, 

 when we visited this neighborhood together. A raft of boards 



5 lwmuvwu * V D 



had drifted upon the inner side of Kiawah point, and lodged on 

 the flat at the foot of one of these hills, by which it was soon 

 covered, and after the lapse of some time, the length of which 

 was not remembered, it was seen to protrude from the oppo- 

 site side. 



The surf has made considerable breaches in the islands of 

 Polly, Coles and Kiawah, to the enlargement of which the wa- 

 ters from the creeks in the rear of the two last named have con- 

 tributed in no slight degree. But the sands from these have only 

 been removed, to contribute to the formation of the large bank, 

 to which I have already alluded. 



Let us now resume the examination of the formation under- 

 lying the city of Charleston, as developed by the auger used in 

 boring the artesian well, and also as exposed in the creeks and 

 rivers of the vicinity. Beneath the ridges of yellow sand which 

 have been described, is a stratum of red ochreous clay, provin- 

 cially termed by the planters, " iron-ore clay, 7 ' which covers an- 

 other of white and grey sands, that are sometimes found also 



between 



from these strata 



which seldom extend twenty feet below the surface of the city- 

 is the " pump-water" obtained. To define the line of separation 



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