220 Geology, §¢. of Tennessee, §:c. 
the ranges, five in number, of the Alleghany mountains. The 
strata lie in a course northeast and southwest, the same as the 
general course of the mountains. The angle which they make 
with the horizon is very variable, from 25° to 45°. - The color 
of the rock varies from blue, and pale blue, to gray, or grayish 
white, frequently it presents a dull earthy appearance. ‘The 
fracture is more or less conchoidal. Sometimes the rock assumes 
_ a different character, and the fracture is uneven, and the texture 
firm. ‘This last is distinguished from the former, not only by the 
fracture, but by the color. It is usually spoken of by the inhab- 
itants as the gray limestone, the color of the other being usuaily 
of a bluish cast. It differs from that also by being less brittle, 
and possessing the quality denominated by stonecutters, * tough.” 
In consequence of this, and its enduring heat better, it is more 
frequently used in building than the other. This variety of 
limestone is not uncommon. Its color is not always gray, some- 
times it is a reddish brown, and sometimes white. Immense 
tities of it, possessing either a grayish or reddish brown color, 
are found in the vicinity of Knoxville, East Tennessee, as one 
range of it is crossed by every road, passing to the south and 
east of Knoxville. Its appearance is that of some variegated 
marbles; white veins penetrate it, and wind through it in every 
direction. Whether any part of it has a texture sufficiently fine 
d firm to be wrought to advantage, is yet to be determined. 
To the eye of a superficial observer, there are many indications 
that it has. A specimen of very fine white marble, resembling 
the Italian white, was shown me in Augusta county, Virginia, 
which was found 15 miles from Staunton, where there is said t 
be a considerable quantity of it. 
on Limestone country in Horizontal Strata. 
The second great division of the limestone country extends, 
on the route which I took, two hundred miles from the Cum- 
berland mountain, and others associated with it southwest, * 
far asthe Dividing Ridge, which separates the waters flowing 
into the Tennessee from those which proceed direct to the 
gulf of Mexico. The grand circumstance which distinguishes 
ee ae 
