722 
NATURAL BRIDGES. 
sixty feet, but more at the ends, and the mass at the summit of the arch 
about forty feet. A part of this thickness is constituted by a coat of 
earth, which gives growth to many large trees. The residue, with 
the hill on both sides, is one solid rock of limestone. The arch ap- 
proaches the semi-elliptical form ; but the larger axis of that ellipsis, 
which would be the end of the arch, is much longer than the trans- 
verse. Though the sides of this bridge are provided in some parts 
with a parapet of fixed rock, yet few men have resolution to walk 
to them, and look over into the abyss. One involuntary falls on his 
hands and feet, creeps to the parapet, .and peeps over it. Looking down 
from this height about a minute, gave Mr. Jefferson a violent head- 
ache. If the view from the top be painful and intolerable, that from 
below must be delightful in an equal extreme. It is impossible for 
the emotions arising from the sublime to be felt beyond what they are 
here; so beautiful an arch, so elevated, so light, and springing as it 
were up to heaven, the rapture of the spectator really is itidescribable. 
This fissure continuing deep, narrow, and straight, for a considerable 
distance above and below the bridge, opens a short but very pleas- 
ing view of the North mountain on one side, and the Blue ridge on 
the other, at the distance of about five miles each. This bridge is in 
the county of Rockbridge, to which it has given name, and affords 
a public and. commodious passage over a valley, which cannot be 
crossed elsewhere for a considerable distance. The strean» passing 
under it is called Cedar Creek. It is a water of James’s river, and 
sufficient in the driest season to turn a gristmill, though its fountain 
is not more than two miles above. 
D on Ulloa mentions a break similar to this in the province of Agaraez 
in South America. It is from sixteen to twenty-two feet wide, one hun- 
dred and eleven feet deep, and of one hundred and thirteen miles con- 
tinuance, English measure. Its breadth at top is not sensibly greater 
than at bottom. Don Ulloa inclines to the opinion, that this chan- 
nel has been eft'ected by the wearing of the water which runs through 
it, rather than that the mountain should have broken open by any 
convulsion of nature. But if it had been worn bv the running of 
water, would not the rocks which form the sides have been plain ? 
or if, meeting in some parts with veins of harder stone, the water had 
left prominences on one side, would not the same cause have some- 
times, or perhaps generally, occasioned prominences on the other 
side also ? Yet Don Ulloa tells us, that on the other side there are 
always corresponding cavities, and that these tally with the promi- 
nences so perfectly, that, were the two sides to come together, they 
would fit in all their indentures, without leaving any void. In fact, 
this does not resemble the effect of running water, but looks ratheras 
if the two sides had been parted asunder. 
The sides of the break, over which is the natural bridge of Vir- 
ginia, consisting of a veiny rock which yields to time, the corres- 
pondence between the salient and re-entering qualities, if they existed 
at all, have now disappeared. This break has the advantage of the 
one described by Don Ulloa in its finest circumstance ; no portion, in 
that instance, having held together during the separation of the other 
parts, so as to form a bridge over the abyss. 
