Eagle Rock and Dans Rock are conspicuous
points reaching 3162 ft. and 2882 ft. above the sea. On the same side of
the Great Valley, south of the Potomac, are the Pinnacle (3007 ft.) and
Pidgeon Roost (3400 ft.). In the southern section of the Blue Ridge are
Grandfather Mountain (5964 ft.), with three other summits above 5000,
and a dozen more above 4000. The Unaka Ranges (including the Black and
Smoky Mountains) have eighteen peaks higher than 5000 ft., and eight
surpassing 6000 ft. In the Black Mountains, Mitchell (the culminating
point of the whole system) attains an altitude of 6711 ft., Balsam Cone,
6645, Black Brothers, 6690, and 6620, and Hallback, 6403. In the Smoky
Mountains we have Clingman's Peak (6611), Guyot (6636), Alexander
(6447), Leconte (6612), Curtis (6588), with several others above 6000
and many higher than 5000.

In spite of the existence of the Great Appalachian Valley, the master
streams are transverse to the axis of the system. The main watershed
follows a tortuous course which crosses the mountainous belt just north
of New river in Virginia; south of this the rivers head in the Blue
Ridge, cross the higher Unakas, receive important tributaries from the
Great Valley, and traversing the Cumberland Plateau in spreading gorges,
escape by way of the Cumberland and Tennessee rivers to the Ohio and
Mississippi, and thus to the Gulf of Mexico; in the central section the
rivers, rising in or beyond the Valley Ridges, flow through great
gorges (water gaps) to the Great Valley, and by south-easterly courses
across the Blue Ridge to tidal estuaries penetrating the coastal plain;
in the northern section the water-parting lies on the inland side of the
mountainous belt, the main lines of drainage running from north to
south.

_Geology._--The rocks of the Appalachian belt fall naturally into two
divisions; ancient (pre-Cambrian) crystallines, including marbles,
schists, gneisses, granites and other massive igneous rocks, and a great
succession of Paleozoic sediments. The crystallines are confined to the
portion of the belt east of the Great Valley where Paleozoic rocks are
always highly metamorphosed and occur for the most part in limited
patches, excepting in New England and Canada, where they assume greater
areal importance, and are besides very generally intruded by granites.
The Paleozoic sediments, ranging in age from Cambrian to Permian, occupy
the Great Valley, the Valley Ridges and the plateaus still