44 GEOLOGY OP THE NAERAGA^SETT BASIK 



The conditions of the surface are in the main as shown in PL I, wi.th 

 the exception that occasional outliers of high land are found over the 

 Piedmont district. These outliers have the general aspect of ancient 

 islands, the bases of which have of late been elevated above the sea 

 level. 



Perhaps the best instance of these structures is afforded by King 

 Mountain, North Carolina, which, as has recently been shown by the studies 

 of Prof. Collier Cobb, of the University of North Carolina, is an insular 

 mass which has by elevation been embodied in the area of the emerged 

 continent. 



It should be said that this bench, with local variations, extends along 

 the Atlantic coast of the continent as far north as the St. Lawrence district, 

 but that the ancient islands are nowhere so well shown as in the Carolinian 

 section. 



The foregoing statements Avill make plain the working hypothesis as 

 to the erosion of the East Appalachian reliefs. We see that these moun- 

 tains lie in the realm of the marine bench, that border land of the continent, 

 where the repeated up and down goings of the sea bring the machinery of 

 the surf and the other erosive agents of the coast line — the frost, the tides, 

 and the winds — to bear in succession on every part of the surface. In 

 recent years there has been a disposition to deny to marine action any 

 considerable effect on the topography of a country. This limited view 

 is a natural recoil from the old notion that the sea is the principal agent 

 in land carving. From overestimating the value of a natural agent, the 

 inevitable step is toward an underreckoning, which seems in this case to 

 have gone altogether too far. A part of the misestimation as to the ero- 

 sional value of the shore agents is due to the study of coastal processes in 

 what we may term adjusted shore lines, such as are to be found where the 

 sea has acted for a long time on a coast where the lands have not altered 

 in their position with reference to the sea. In such conditions the sea, by 

 a complicated system of actions, builds a series of obstructions in the way 

 of shallows and beaches, which serve to bar the land from its assault, and 

 which often cause the energy of the waves and. tide to be expended in such 

 wise as little if at all to erode the land. Wherever we are able to study the 

 action of the sea where the land is rapidly oscillating, we note at once the 

 great increase in the effectiveness of the ocean's work. Thus, on the coast of 



