1863.] 289 [Lesley. 



open upon him in the same form anew, so soon as the denudation of 

 the Cretaceous and Tertiary surfaces come to be regarded as in like 

 manner in harmony with those of older dates. 



At Cornwall, sis miles south of Lebanon, hills of New Red Sand- 

 stone, three, four, and perhaps five hundred feet high, stand, looking 

 in upon the great Silurian plain, like Peris at the gates of a Paradise 

 they cannot enter. If along this line ?i fault, has in fact carried the 

 New Red down to the present level of the Silurian plain, the denu- 

 dation of the two surfaces is nevertheless so far one phenomenon, 

 that in its present condition it is to be explained by reference to 

 actions subsequent to the deposit of the Conglomerate, or upper- 

 most New Red layer, the so-called Potomac marble. But the hypo- 

 thesis of a fault along the south base of the South Mountain is a 

 pure fiction of embarrassment. If it existed anywhere, it must ex- 

 tend several hundred miles, and be approximately a straight line. 

 The most cursory glance at the geological map of Pennsylvania will 

 satisfy any one that no such fault exists. The succession of spurs of 

 the mountain range forbids it. The gophered edge of the New Red 

 on the Lancaster County limestone forbids it, and shows how entirely 

 superficial the New Red is. No river section shows the fault. It 

 is a pure fiction. The northwest dip of the New Red against the 

 Azoic mountain range is still a problem to be solved. 



The hypothesis of suboceanic erosion, contended against by the 

 geologists of the United States almost from the beginning, is fast 

 losing, if it has not lost altogether its hold upon the European mind. 

 The conviction is well established, which we freely expressed years 

 ago, that the ocean is a builder and not a leveller. Like the quie- 

 tistic and subjective letter M, which was its symbol in ancient litera- 

 ture, the main, the murmuring Typhon, has always been the absorber, 

 and the mother of multitudes. While the fringe of foaming breakers, 

 the Herculean Hydra, and in fact all river water, the rushing and 

 hissing Typhon, of which the letter S was symbolic, has always been 

 the destroyer, the enemy of the established, the ravager of the sur- 

 face. It was upon this basis that some subaerial cataclysmic hypo- 

 thesis like that of Professor Rogers came to be favored by those 

 who knew the grandeur of the work which had been done by the 

 denuding force whatever it was, among the paloeozoic anticlinals of 

 America; and who felt the perfect harmony which reigned over the 

 whole expanse of the phenomenon, from the Tertiary seaboard of the 

 Atlantic and the Gulf, past the beds of the great freshwater Devo- 



VOL. IX. — z 



