IG THE COAST REGION. 



" Rising Sun," a large vessel, with three hundred and forty -six passengers, 

 that could not cross the Charleston bar, made its way without a pilot to 

 the present site of Georgetown, a thing utterly impossible during the last 

 one hundred years. Moreover, a comparison of the soundings on Chart 

 No. 428, of U. S. Coast Survey of 1877, with a Chart of the same locality, 

 published in Drayton's View of Soutli Carolina, in 1802, shows that, instead 

 of any scouring out or erosion, there has been a great filling up in the 

 interval. Seaward from Georgetown Light House, Drayton gives depths 

 of 9 feet to 30 feet, where Captain Boutelle only found 0| feet to 19 feet 

 of water. Inside the entrance, where the water once was 30 to 36 feet, the 

 mean level of low tide now only gives a depth of 9 to 31 feet. Ten sound- 

 ings taken off South Island average now 7| feet, while ten soundings in 

 the same locality on Drayton's Chart average 18 feet. 



It would seem, then, according to the fourth and remaining hypothesis, 

 that the Sea Islands were an outgrowth of the mainland into the sea. 

 And that this is but a continuation of tlie process by which the tertiary 

 plain, stretching back to the feet of the ancient and lofty Apalachian 

 chain, was itself formed. The broadest portion of this plain lies under' 

 the loftiest and broadest vestiges of this mountain chain, whose denuda- 

 tion furnished the most abundant material. Northward, under lesser 

 elevations, which could only furnish less material, the tertiary plain 

 gradually wedges out and the sea approaches the mountains. The slow 

 uniformity of this long process of growth is further shown by the gentle 

 and uniform slope with which this plain approaches the sea. Nor does 

 it end abruptly there. For one hundred miles or more the sea scarcely 

 exceeds one hundred fathoms, until it suddenly deepens to two thousand 

 fathoms under the gulf stream. The sea islands are not isolated phe- 

 nomena peculiar to this period. In the interior the intricate network of 

 swamps and bays corresponding with the present inlets, creeks and rivers 

 of the coast, represent the old channels and deltas through which the 

 waters flowed, when the pine fiats and ridges, still resting in the meshes 

 of this network, were themselves veritable sea islands. 



Prof Toumey refers to Murphy's island, south of South Santee inlet, as 

 furnishing a typical illustration of the manner in Avhich this occurs. A 

 bar is formed at the mouth of the river by the action of the ocean. 

 " Breakers make their appearance seaward, and gradually push forward 

 the sand as they approach the shore. When the sand rises above the 

 surface, the water becomes too shallow to produce breakers ; they disap- 

 pear, and commence again off the shore, and further south. An eddy is 

 formed between the sandbar and the shore, in which the river deposits 

 its sediment. From an eddy it is changed, first into a lagoon, and then 

 into a mudflat, which increases until the level of high water is reached. 



