ELISHA MITCHELL SCIENTIFIC SOCIETY 110 
easterly strike and dip at steep and varying angles. 
Near the eastern border of the region there is another 
but more narrow and irregular belt of rock of a some- 
what similar character, following approximately the gen- 
eral position of the Blue Ridge mountains. 
The general physiographic features of the region are 
those mountains and hills with narrow valleys. It may 
be restated here that the rivers of this region have their 
sources mainly along the western slope of the Blue Ridge, 
and that with the exception of New river, near the north- 
ern boundary, they flow in a general northwesterly di- 
rection across the upturned edges of both the gneissic 
and the more recent bedded rocks. ‘The elevation of the 
country is so great and the descent of the streams so 
rapid that the general courses of the principal rivers have 
been but little modified by geologic structure, though 
their courses lie directly across the strike of the rock ; 
and the resulting conditions are such as to produce along 
the streams occasional rapids and cascades. LEspecially 
would this be the case in the western counties, where the 
Pigeon, the Tuckasegee, the Little Tennessee and the 
Hiwassee break through the Great Smoky mountains, and 
in doing so cross a variety of limestone, quartzite and con- 
glomerate beds which go to make up the geologic forma- 
tion of that area, but for the fact that during the long 
period of time that these streams have occupied their pres- 
ent channels, owing to the rapidity of their flow and the 
large quantities of abrading materials, such as sand, grav- 
el and bowlders, carried down in their currents, the va- 
riations in the obduracy of the rocks, crossing these 
stream beds seldom result in cascades of large propor- 
tions, for the reason that the would-be projecting ledges 
of rock across the stream bed are kept down near the 
general level by these eroding agencies. 
A number of the smaller tributary streams flow in either 
