216 Geology, Fc. of Tennessee, Gc. 
€tructed. It is composed of fine silicious grains, is easily wrought, 
and-from its color, has the appearance at a small distance of 
white marble. ‘ 
Beautiful Breccia. 
- jt is also in the valley of this river, and not far from its fa- 
mous passage through the Blue Ridge, that immense quarries 
of beautiful Breccia have been opened. This rock was first 
brought into use by Mr. Latrobe, for some years employed by 
the government as principal architect. It is composed of peb- 
bles, and fragments of silicious and calcareous stones of almost 
every size, froma grain, to several inches in diameter, strongly 
and perfectly cemented. Some are angular, others rouD 
‘Their colors are very various, and often bright. Red, white, 
brown, gray, and green, are alternately conspicuous, with ev- 
ery intermediate shade. Owing to the silicious stones which 
are frequently imbedded through the mass, itis wrought with 
much difficulty; but when finished, shows a fine polish, and is 
unquestionably one of the most beautifully variegated marbles, 
that ever ornamented any place. It would be difficult to con 
ceive of any thing more grand than the hall of the representa 
tives, in. the Capitol, supported as it is by twenty or thirty pi 4 
lars formed of the solid rock, and placed in an amphitheatrical 
range; each pillar about three feet in diameter, and twenty i 
height. Some idea of the labor wich is employed in working 
the marble may be formed from the fact, that the expense of 
each pillar is estimated at five thousand dollars. The spetr 
mens in your possession, are good examples of its gene y 
ture, but convey no adequate idea of its beauty. 
Petrifaction of Wood. 
It will be proper to notice in this place, @ petrifaction of 
wood which ie fouka ek the road from Washington 7 
ricksburgh, 16 miles from the latter, and four miles north of the 
court-house in Stafford county. It is remarkable for its siz® 
rather than for any singularity in the composition. It was 
