200 GEOLOGICAL SURVEY . 
This would have been a puzzling instance, if the whole process was not presented before one’s 
eyes. Fig. 34, which represents a section across Cole’s Island, will explain the appearances pre- 
sented at this locality. 1 is the “back beach,” or flat behind the sand-hills; 2, sand-hills; 3, bed of 
marsh-mud; a,a Pine, with tap-root extending into the mud; b, Live-oak, undermined by the waves, 
but yet attached to the bank; ¢, stumps; d, Live-oak standing on oyster bed. 
This section needs scarcely any explanation. The Pines grow in the sand, down to the water 
line, and but a few inches above it, where the slightest encroachment of the salt water kills them, 
when they break off, generally below the stool, leaving the tap-root standing. The Live-oak, on 
the contrary, having no tap-root, is supported by its wide-spreading lateral roots, by which it is 
often retained in an erect position when the sand is washed away; and, on account of its great dura- 
bility, remains, when there is nothing but the tap-roots of the Pines left. 
Near this place another interesting record of the mutations of land and water is seen. A house 
once stood here, having a well back of it, on the island. The house is gone, but the curbing of 
the well, which consisted of a cask, still remains on the beach, but below high-water—having sunk 
into the loose sand. Had the coast, in the vicinity of Charleston, sunk at this rate, St. Michael’s 
Church, instead of being the ornament of the city, would, at this moment, be a geological monu- 
ment, of the greatest interest. 
I have thus presented some of the most striking phenomena which have been supposed to result 
from a gradual subsidence of the solid crust oi the earth, on the coast of South Carolina. If any 
one will examine the localities that I have indicated, I am persuaded that he will come to the same 
conclusion that I did, namely, that there is not a single instance of submerged stumps that cannot 
be traced to the encroachment of the ocean, without supposing any change in the relative level of 
land and water, on the coast. 
Those writers who have referred them to the latter cause, erred, in not having first studied the 
nature and level of the swamps in which the trees grew whose stumps are found submerged, and 
in not distinguishing tap-roots from true stumps. 
Recent CHANGES IN THE CHANNELS OF Rivers.— ABSENCE OF F'LUVIATILE SHELLS IN 
TertTiaRy Deposits. 
There is one other subject connected with recent changes that must be mentioned here; I mean 
the occurreuce of bluffs on the right banks or western sides of the rivers, in the lower part of the 
State. I have heard the same remark made in relation to the rivers of Virginia and North Caro- 
lina, but [cannot speak of these from observation. At all events it is so obvious in South Carolina, 
on all the rivers, as was first pointed out by Mr. Ruffin, that it could not escape observation. I 
have already shown how the low land, opposite to the bluffs, is formed; and it only remains now 
to show what cause has produced this tendency of the vivers towards the West. 
The question is often asked, were there no rivers on the Atlantic slope, during the Tertiary 
period? and if so, why have we no fresh water fossil shells in the deposits of that period? 
by a circular bank of shells, it furnishes a convenient site for a dwelling, It appears as if the shells were thrown around the huts, in 
the centre, inhabited by the Indians. It is remarkable that the shells are disposed in layers: a layer of conchs, next one of clams, 
and then one of oysters—as if eaten as they were in season. 
