INTRODUCTION. 
29 
play through the uncounted centuries which make the lifetime of a con- 
tinent, disintegrated and worn away the vast mass, until it is but a skele- 
ton of what it was, transporting the ruins successively to lower levels, 
and finally to the sea. Of course in this process the softer rocks, as the 
shales, limestones and certain micaceous slates, would suffer a greater 
amount of abrasion than the harder masses, such as the siliciousand horn 
blendic slates, schists and gneisses. Hence the present mountain chains 
are composed of the latter, while the rivers have scooped out their val- 
leys through the tracts occupied by the former. 
There are abundant illustrations of these statements throughout this 
interesting region. It will be sufficient to cite the great valley of Chero- 
kee, hewn out of the limestone, and following that formation closely, far 
down into Georgia ; the valley of the French Broad through Transylva- 
nia and Henderson, which has been excavated in a similar and easily dis- 
integrate rock ; and the valleys of Yadkin and Catawba. The rivera 
east of the Blue Ridge usually take a course at right angles to the direc- 
tion of that chain, for the obvious reason that that is the line of quickest 
descent. But these two last named rivers form an exception to the rule, 
striking off for fifty or sixty miles in a northeasterly course, nearly paral- 
lel with the Blue Ridge, taking the tract of the softer rocks and making 
a grand easterly sweep around the harder strata of the Brushy and South 
Mountains. 
The great geological fact underlying and explaining much that is pecu- 
liar in the grand topographical outlines of the State as above sketched, is 
the existence of a transverse line of movement, or axis of uplift in this 
part of the Appalachian system. This is sufficiently evident from one 
observation, — that the dips of the later formations are north along the 
northern border of the State, and southerly along the south and south- 
easterly outcrops of the same beds. And the dips are by no means in- 
significant, ranging from 15 to 70 degrees. To explain these facts there 
is required quite as great an upheaval along an east and west axis as is 
sufficient to account both for the excessive elevation of the continental 
mountain system in this region and for the great eastward protrusion of 
the Atlantic coast line. 
Valleys. — T here are no great valleys in this State comparable to the 
Valley of Virginia, or the Valley of east Tennessee. But each of the 
numerous rivers has hewn out a narrow valley for itself, in the bottom of 
which lies its present channel. The most considerable and best defined 
of these are found in the mountain region just described. The most 
notable and the largest among them is the Valley of the French Broad y 
which is about 50 miles long and has a varying breadth of 10 to 25 miles. 
