97 JOURNAL OF THE 
eral faults; this succession of variations giving rise toa 
succession of rapids and shoals, with an aggregate fall 
of 85 feet in a distance of 9 miles. For this distance the 
river flows through a deep and open gorge flanked by 
hills which, near Gaston and a short distance westward, 
are capped with unconsolidated gravels, presumably of 
Potomac age, and bordered by terraces of more recent 
age, probably post-tertiary (Columbia). In the neigh- 
borhood of Weldon and eastward the rocky hills give 
places to the terraces and plains of the coastal region, 
composed of gravels, sand, loams and clays, varying in 
age from Potomac at the bottom to Columbia at the top. 
ON THE TAR RIVER. 
On the Tar river there is but one large waterpower, 
that at Rockv Meunt, which may be considered as being 
at the eastern margin of this zone and some 20 miles 
eastward of the western border of the coastal plain 
region. The Tar rises nearly 100 miles to the northwest 
of this point and crosses successively several granitic, 
schistose and slaty belts of rock, but owing to the slight 
elevation of this upper part of its basin above that of the 
coastal plain, the long period during which the rocks of 
this upper basin have been undergoing su1face decay, 
and the long period during which this stream, with no 
ereat volume of water, has been slowly carving out its 
channel, its freedom at the present rime from conditions 
favorable to waterpower is easily understood. At Louis- 
burg there is a fall of several feet owing toa change in 
the character of the granitic rocks. At Rocky Mount it 
turns eastward and crosses a ledge of hard granitic rock, 
on the eastern slopes of which there is a natural fall of 
about 15 feet in the course of 100 yards. It is on the top 
of this granite ledge that the dam has been built which 
serves for the full development of this waterpower tor 
operating the Rocky Mount cotton-mill. 
