Drainage of the Province. 95 
extended southwestward along the axis M N,so that in very 
recent geologic time the Tertiary peneplain from Asheville to 
Atlanta and southwestward has been elevated to its present 
position. 
Movements have occurred along some minor axes chiefly of 
subsidence, but their exact date cannot be fixed. ‘ 
The latest movements which can be detected in the province 
are along the axes K Land OP. That along K L has resulted 
in a slight ponding of the Tennessee river in the vicinity of 
Huntsville, Alabama, while the uplift along O P has affected 
the Cumberland river above point Burnside, Kentucky, in a 
similar manner. 
Part II.—DRraAtnaGE DEVELOPMENT. 
SUBDIVISIONS OF THE PROVINCE. 
Geologically, and topographically as well, the southern Appa- 
lachian province falls into four well-marked divisions. These 
are (1) an eastern piedmont plain, sloping gently seaward and 
composed of metamorphic and crystalline rocks; (2) a montanic 
tract, embracing the Blue ridge and the Great Smoky range with 
its many outliers and containing chiefly crystalline rocks with 
sediments which have undergone various degrees of metamor- 
phism ; (3) a central broad valley with numerous parallel ridges 
of Paleozoic sediments ; (4) a western dissected plateau of upper 
Silurian and Carboniferous rocks. 
OUTLINE OF THE PRESENT DRAINAGE. 
In the northern portion of the province the water parting be- 
tween the Atlantic and Gulf drainage is westward of the Appa- 
lachian valley. The Potomac heads upon the edge of the plateau 
and flows eastward across the Appalachian valley, the montanic 
tract and the piedmont plain. From the western point of Mary- 
land the divide passes nearly due southward, crossing the Appa- 
lachian valley diagonally, so that the James and Roanoke drain 
only the eastern part of the valley, but, like the Potomac, flow east- 
ward across the montanic tract and the piedmont plain. South 
of these streams the divide follows near the eastern margin of 
the montanic tract to its southern extremity, only the eastern 
slope being drained by streams crossing the piedmont plain to- 
14—Nart. Grog. Maa., vou. VI, 1894. 
