108 Hayes and Campbell—Appalachian Geomorphology. 
ward had cut broad baselevel valleys, described in Part I, in 
the soft horizontal limestone of the plateau region and in some 
of the folded rocks immediately eastward. The greater part of 
the Sequatchie anticline had thus been reduced to a peneplain 
continuous with the more extensive one through the plateau to 
the westward. Cumberland river had cut deeply into the old 
Cretaceous peneplain and again baseleveled its valley in the soft 
limestones of the plateau region. It also probably baseleveled a 
small area of folded rocks in the Appalachian valley—the pres- 
ent basin of Powell river which then flowed westward through 
Cumberland gap. The New-Kanawha had cut an extensive 
peneplain in the Carboniferous limestone on the eastern side of 
the West Virginia coal field, and also in the folded Cambro- 
Silurian limestone of the valley region. The latter limestone is 
less soluble and homogeneous than the former, so that its out- 
crops were less perfectly reduced, forming a rolling surface in- 
stead of a level plain. 
In the southeastern portion of the province the uplift of the 
Cretaceous peneplain was so slight that the streams were scarcely 
at all accelerated, and in the vicinity of Atlanta deepened their 
channels not more than 100 feet throughout the whole Tertiary 
cycle. 
From the New-Kanawha southwestward to the margin of the 
Tertiary sea the Appalachian river and its tributaries had cut 
deeply into the Cretaceous peneplain and reduced all areas of 
soft rocks, more or less completely, to the new baselevel. The 
-physiography of this Tertiary peneplain has already been de- 
scribed in some detail. The plain was very perfectly developed 
over areas of pure limestone, while silicious limestones, shales 
and sandstones formed a rolling surface or ridges of varying 
heights, in proportion to their induration or capacity for resist- 
ing erosion. 
It seems probable that the great Appalachian river was formed 
by two main branches which flowed in nearly parallel courses 
to their junction west of Rome, Georgia. The western branch 
followed the present course of the Clinch and Tennessee to 
Chattanooga, and thence of the Chickamauga and Chattooga 
to the junction of the latter with the Coosa; the eastern branch 
followed the course of the Holston and continued southward 
from Knoxville along the base of the Great Smoky mountains 
‘ 
