THE COAST REGION. • 15 



The origin and formation of the sea islands may be accounted for by 

 one of four possible suppositions. 



1st. By a subsidence of the coast resulting in the submergence of the 

 lower lands. This explanation was offered by Sir Charles Lyell, and 

 recently by Professor G. H. Cook, wjho believes that the whole Atlantic 

 seaboard is sinking. 



2d. By the elevation of the sea bottom. This theory has not been 

 maintained by any one and need not be considered. 



3d. By the erosive action of the tides and currents of the sea, cutting 

 into the shore line and detaching, as it w^ere, portions of the mainland. A 

 theory of Professor Shaler. 



4th. By an outgrow^th of the land into the sea, resulting from the dei)0- 

 sition at the mouths of the rivers of the detritus- brought down by their 

 currents from the interior. 



Mr. Tuomey shows in detail that the instances of the submergence of 

 oak, pine and cypress trees, and other landmarks, adduced as evidence 

 of subsidence of the coast, occur in localities of restricted area. That the 

 lands immediately adjacent show no signs of participation in this move- 

 ment, which they would do if the cause were so general a one as the sub- 

 sidence of the coast. That encroachments of the sea of a purely local 

 character after storms explain the phenomena. And lastly, that if it were 

 admitted that the submerged live oak and pine stumps near Little River, 

 or the dead cedars and cypress of the " Church Flats," on Wadmalaw 

 island, were evidence of a subsidence of the coast, the rate at which it is 

 progressing, according to this datti, is so rapid that on this low lying 

 shore, sea w^ater would long since have been admitted to the rice planta- 

 tions, totally destroying them, and that St. ;Michaers Church, the orna- 

 ment of Charleston, would now be a geological ;nonument of the greatest 

 interest, with its tall spire only protruding above the waves. 



If the sea islands resulted from the erosive action of ocean currents, we 

 should expect to find them most numerous in localities where the erosive 

 action is most manifest. Such a locality is the recess of Long bay, hol- 

 lowed out by the action of the sea, between Winyaw bay, the outlet of the 

 great rivers of South Carolina and the outlet of the rivers of North Caro- 

 lina at Cape Fear. So far is this from being the case, however, that there 

 is not a single island on this incurving line of erosive coast. On the con- 

 trary, it is only when the land bellies out into the sea near where the 

 great rivers deliver their detritus to its waves that the seii islands make 

 their appearance. 



At this point, namely, at Georgetown entrance, we look in vain for 

 evidence of erosion. The records all point the other way, to a gradual 

 encroachment of the land upon the sea. Thus, in the year 17U0, the 



