Shaler.] 226 [March 2, 



height, they steadily increase as we go nearer to the centre of the 

 Bay, until at Fort Pulaski, at the mouth of the Savannah River, 

 they are over seven feet in height. This heaping up of the .tide 

 in this bay may be entirely due to the usual action of converging 

 shores upon the tidal wave which flows into the bay they form; 

 though it does not seem as if the indentation was sufficiently deep to 

 produce so great an effect. 



If we go back to the time when this shore began to emerge from 

 the sea, it will be seen that where the tide was of considerable height 

 it would tend to sweep around the low islands formed by the upper 

 part of the ridges before described, and to dig out the incoherent 

 sands which formed the bottom of the troughs between them. As 

 the shore gradually rose higher these water ways would be more de- 

 fined ; but if there was an extensive tide water surface left, the scour- 

 ing action would be quite decided, and these channels might in time 

 acquire considerable depth, 



A careful reconnaissance of the shore between Capes Hatteras and 

 Florida will show the observer that the Sea Island topography begins 

 where the tide rises above about four feet, and becomes more and 

 more marked as we go towards regions Avhere the tide becomes higher 

 and higher, or in other words, that in a general way the amount of 

 complication of outline of the shore line is proportionate to the height 

 of the tide. 



Geological History of the South Carolina Coast Region. 



The physical geography of this region affords the key to its geo- 

 logical history, or to that portion of it, at least, which has given it 

 the character it has at present. But to understand the more remote 

 history of this region we must go back to a time when the shore 

 line was at least two hundred miles west of its present position. At 

 the close of the Cretaceous era the shore of this southeastern border 

 of the continent lay near to the base of the Alleghany Mountains. 

 The uplifts at the close of the Eocene probably carried the shore 

 line some distance to the eastward, but just how far it is not easy to 

 say, as subsequent wearing action has destroyed a part of the record. 

 The elevation which closed the Miocene seems to have been far 

 greater than that which came at the end of the preceding period. 

 It appears as if the shore line must have come at some points, es- 

 pecially on the southern part of South Carolina, nearly as far east as 

 the present coast. 



