Round about Asheville. 299 



not been worn down. A topography of diiferential uplift gave 

 place to one of differential degradation. And to the latter the 

 dome-like " balds " of the Unakas belong. Those massive sum- 

 mits of granite, quartzite and conglomerate are not now cut 

 by running waters ; they are covered with a mantel of residual 

 soil, the pi'oduct of excessively slow disintegration, and they are 

 the remnants of a surface all of which has yielded to degradation, 

 save them. In time the streams will cut back and carve jagged 

 peaks from their masses, but standing on their heights my thought 

 has turned to the condition they represent — the condition that is 

 past. And thus in thought I have looked from the Big Bald out 

 on a gently sloping plain which covered the many domes of 

 nearly equal height and stretched away to merge on the horizon 

 in the level of the sea. That, 1 conceive, was the first base level 

 plain of which we have any evidence in the Appalachians and 

 from that plain our present valleys have been eroded. The con- 

 tinental elevation must then have been 3,000 or 4,000 feet less 

 than it is now, and the highest hills were probably not more than 

 2,500 feet above the sea. This was perhaps a period of constant 

 relation between sea and land, but it was succeeded by one dur- 

 ing which the land slowly rose. The rivers, which had probably 

 assumed nearly their present courses, were revived ; the impor- 

 tant channels soon sank in canons, the tributaries leaped in rapids 

 and cut back into the old base level. The region continued to 

 rise during a period long enough to produce the essential features 

 of the mountain ranges of to-day ; then it stood still in relation 

 to the sea or perhaps subsided somewhat, and the French Broad 

 and probably other rivers made record of the pause in plains like 

 that about Asheville. Again the land rose slowly ; again it 

 paused, and rivers, working always from their mouths backward, 

 carved a base-level in the limestones of the great valley ; but 

 hefore that level could extend up through the gorges in the 

 Unakas, the continent was raised to its present elevation, the 

 streams responded to the increased fall given them and the rivers 

 in the valley began to cut their still incomplete canons. 



Are we not led step by step from these latest sharply cut chan- 

 nels up stream through the chapters of erosion to the still surviv- 

 ing domes of an early old age ? Let us sum up the history we 

 have traced. There is reason to believe that : 



1st, The consequent topography of the earliest Appalachian 

 uplift was entirely removed during a prolonged period of erosion 

 and was replaced by a relief of differential degradation. 



