On the physical geology of Tennessee. — Foerste. 347 
were the Archaean Protaxis on the east and the crest of the Cin- 
cinnati-Nashville anticlinal axis oh the west. 
This great valley was more or less subdivided by minor parallel 
flexures. Thus the Sequatchee anticlinal, at present occupied by 
the valley of the Sequatchee river for a distance of sixty miles ex- 
tends along the middle of this great valley. ' ' The flanks of the 
Sequatchee valley are composed of Carboniferous grits and shales 
resting on limestone, from below which the Devonian and Silurian 
strata emerge with a dip in the direction of the sides of the val- 
ley. The valley is therefore clearly in the line of an anticlinal 
axis, and to this it probably owes its origin, though it is possible 
that there ma} r be a fault here running in a parallel direction, 
along which river-erosion has acted through a lengthened period. 
The Little Sequatchee, a smaller valley further to the west is prob- 
ably due to a similar anticlinal flexure. " The Tennessee itself, 
north of Chattanooga, is figured as occupying a secondary anti- 
clinal valley, just east of the present Cumberland plateau. The 
great valley of east Tennessee, stretching eastward as far as the 
Archaean Protaxis, is occupied by formations often highly inclined 
or thrown into flexures. 
The region along the Archaean Protaxis, which was perhaps 
never altogether submerged, was upraised gradually into high 
land, and thus subjected to extensive erosion long before the more 
western districts which remained under water and undenuded, or 
were but slightly emergent. ' ' As time went on, these western 
tracts wherever in the line of anticlines, were themselves ele- 
vated and eroded, and ultimately the synclines themselves. " It 
- is evident from the context that the author ascribes most of thi& 
erosion to subaerial influences brought to bear upon the land areas- 
while gradually arising from the sea. According to this, the 
synclines being the last parts to emerge from the sea were the last 
to suffer erosion. But even then the syncline of the Cumberland 
plateau region was protected by the massive Carboniferous grits- 
which still capped them, whereas erosion removed this protection 
from the earlier exposed sides of the great valley, the regions of 
the Nashville anticlinal and the valley of east Tennessee. The 
cutting back of the strata no longer protected by these grits, 
in the direction of their dip, left the s} r nclinal area relatively 
higher than the anticlines and thus formed the Cumberland pla- 
