514 REPORT OF NATIONAL MUSEUM, 1904. 



an infinite series of oceanic degradations, beginning with the uplift and 

 still in progress. Instead, he adopted the supposition of a succession 

 of denuding actions of unknown force and indefinite number. "A 

 homogeneous element with sufficient force, acting either by one or by 

 repeated blows," would bring about the present condition of affairs. 



No one will deny that water, if obtained in sufficient quantity at a sufficient veloc- 

 ity, would be such an agent. In the acknowledged instability of the crust of the 

 earth, in its acknowledged less stability in ancient times than now, we find the pos- 

 sibility, nay, we feel the certainty, that the oceans have at times been launched 

 across the continents, and we need nothing more to satisfy all the conditions for an 

 explanation of Appalachian topography. 



One great obstacle, Lesley thought, in the way of topographical 

 science among geologists — 



has been an innocent ignorance of the titanic postulates upon the ground, and there- 

 fore an inability to reconstruct in imagination the awful vaults of rock which have 

 been removed from over at least 50,000 square miles of the surface of the United 

 States merely along the one belt of the Appalachian Mountains, between the coal 

 area and the Blue Ridge range. 



However this may have been, Lesley himself could not be accused 

 of any such innocent ignorance and consequent impotency of imagina- 

 tion. Thus, when speculating on the character of the folds of the 

 Appalachians, as controlled by the roughness of the old surface of the 

 more or less disturbed and eroded sedimentaries and the thinness of 

 the newer formations, whereby there was a tendency for more or less 

 hitch and catch below and crack and shove above, he showed that such 

 features were here reduced to a minimum, and hence probably the high 

 anticlines were unbroken at the crest. 



As a whole, the plicating energy must have acted with a steady evenness of thrust, 

 which carried up the anticlinal waves of the crust unbroken, and in some cases to a 

 height of between 5 and 10 miles above the present surface level. 



Truly a strange admixture of views. As a modern catastrophist he 

 was equaled only by Clarence King. 



It was the opinion of Rogers, it will be remembered, that the great 

 amount of erosion which had manifestly taken place in the Pennsyl- 

 vania Appalachians was cataclysmic, the consequence of a great rush 

 of waters or body of water over the face of the continent at the time 

 when the coal era was about to be terminated by the upheaval of the 

 whole Appalachian belt of earth crust, when it was thrown into waves 

 or folds. Lesley at first accepted this view and even as late as 1864 

 confessed himself as not entirely convinced that such a cataclysm was 

 not necessary in order "to explain the earlier and perhaps the larger 

 part of the whole phenomenon." He did not, however, accept Rogers's 

 "pulsating planetary lava-nucleus" theory to account for the primary 

 origin of the range, but felt that the force of lateral thrust caused by 

 shrinkage from a cooling globe better accounted for the surface convo- 

 lutions as he saw them. 



