Shaler.] 120 [February 1, 



miles to the west of that city, is at the surface of the ground, is de- 

 pressed to a depth of seventy-five feet, as was demonstrated by the 

 section made by the artesian well at that point. The existence of a 

 continued submergence at this point of our shore is a matter of great 

 economic, as well as scientific importance. As no part of the east- 

 ernmost one hundred miles of the State can be submerged to the 

 depth of fifty feet without either becoming covered by the sea, or so 

 liable to overflow as to be useless for cultivation, it follows that a 

 sinking of a few feet a century is a matter of great concern to those 

 who would anticipate the future of this part of our national area. 



It is a well ascertained fact that a rise in the whole shore line from 

 New York to Greenland has taken place since the close of the glacial 

 period. This movement has most likely taken place in connection 

 with the removal of the glacial sheet which, for some as yet unex- 

 plained reason, seems to have brought about a subsidence proportion- 

 ate to the depth of the icy accumulation. It seems not at all unlikely 

 that coincident with this re-elevation of the northern coast, there 

 began a subsidence in the southern part of the Atlantic shore of the 

 United States. It is certain that from New York southward to 

 Charleston, there are, from point to point, indications of subsidence 

 of a date about as recent as the elevation to the north of that point. 



The form of the debouchures of the rivers which empty along this 

 part of the coast, giving us the broad waters known as Albemarle 

 and Pamplico Sounds, is not readily explained. Unlike the greater 

 inlets of the Delaware and the Chesapeake on the north, these estua- 

 ries do not seem to have been formed by ice action. They are far 

 shallower than those bays, and do not, like them, extend all the way 

 from the shore to the hard rocks and high lands of the interior. It 

 would be difficult to suppose that glacial action could have excavated 

 their mouths and not cut out the upper part of their courses deeper 

 than we find them to be. I am inclined to think that they have been 

 formed much in the fashion of the estuary known as the Broad River 

 in South Carolina. A river carrying comparatively little sediment, 

 and thus having a small delta-forming power, has had its mouth grad- 

 ually depressed by the sinking of the shore, and has thus naturally 

 formed an estuary as wide as that part of the valley which was sub- 

 merged. 



It seems likely that at the time when the beds of these streams 

 were first thus depressed the barrier of the Hatteras reefs had not 

 been raised above the sea, and that the run of the tides in these 



