198 Holmes s Notes on the Geology of Charleston. 



in the Ashley and Cooper river marls, though this fluid oozes 



slowly and in small quantities through every part of them. 



The most wonderful feature of this older bed is the number of 

 subterranean streams of fresh water by which it is traversed. 

 The surface of the Santee region abounds with funnel-like de- 

 pressions, called lime-sinks; caused, apparently, by the falling in 

 of the marl and superincumbent soil, which had become too thin 

 to support its own weight, from the washings of the stream be- 

 neath. Instances have been known of the ploughman, with his 

 team, being engulfed by the sudden falling in of one of these 

 lime-sinks. 



During the spring of the present year, the swamps having been 

 dried up, and the rivers reduced to a very low state, from the 

 drought which had prevailed all winter, I availed myself of the 

 opportunity thus afforded of examining the exposures of marl on 

 the water-courses of this region, and also some of its beautiful 

 springs, or subterranean streams. 



Woodboo, a plantation belonging to the estate of the late Ste- 

 phen Mazyck, Esq., is remarkable for two springs, the vent of 

 one or perhaps two of these subterranean streams. The waters 

 flow from openings in the marl, four or five feet in diameter, at the 

 bottom of a basin, the area of which is several hundred feet ; and so 

 beautifully clear and transparent are they, that the trout, bream, and 

 other fish, and indeed objects of the smallest size, may be dis- 

 tinctly seen at the depth of twenty or thirty feet. The bluish 

 tinge of the water, too, casts a sombre, but agreeable hue on all 

 around ; and the general effect is not a little enhanced by the wil- 

 lows and cypresses extending their graceful arms above its sur- 

 face, and studding the banks of a considerable stream which, 

 flowing from the basin in a winding course, empties, at the dis- 

 tance of nearly half a mile, into the Santee Canal, the lower sec- 

 tions of which are dependent upon it for their supply of water. 



An incident was related to me in connection with these springs, 

 which will convey some idea of the extent of the subterranean 

 streams of this region, and which, extraordinary as it may appear, 

 a similar and subsequent event, coming within my own observa- 

 tion, leaves me no ground for doubt. I will first relate the one 

 which I witnessed. 



Before reaching Black Oak Lock, I was informed that there 

 was a " break' 7 in the canal at this point, by which all the water 

 from one section had escaped, so as to overflow completely a 

 swamp at a short distance from it, where, owing to the drought, 

 no water had lain for some months previous. Supposing that the 

 "break" in question had occurred in the bank of the canal, and 

 that if large enough to permit the escape of the waters of an 

 entire section, it would expose much of the material composing 



the embankment, I thought myself fortunate in getting such an 



