QUERY V

 

        _Its Cascades and Caverns?_
 
 

        Falling Spring

        The only remarkable Cascade in this country, is that of the

Falling Spring in Augusta.  It is a water of James river, where it is

called Jackson's river, rising in the warm spring mountains about

twenty miles South West of the warm spring, and flowing into that

valley.  About three quarters of a mile from its source, it falls

over a rock 200 feet into the valley below.  The sheet of water is

broken in its breadth by the rock in two or three places, but not at

all in its height.  Between the sheet and rock, at the bottom, you

may walk across dry.  This Cataract will bear no comparison with that

of Niagara, as to the quantity of water composing it; the sheet being

only 12 or 15 feet wide above, and somewhat more spread below; but it

is half as high again, the latter being only 156 feet, according to

the mensuration made by order of M. Vaudreuil, Governor of Canada,

and 130 according to a more recent account.
 
 

        Madison's cave

        In the lime-stone country, there are many caverns of very

considerable extent.  The most noted is called Madison's Cave, and is

on the North side of the Blue ridge, near the intersection of the

Rockingham and Augusta line with the South fork of the southern river

of Shenandoah.  It is in a hill of about 200 feet perpendicular

height, the ascent of which, on one side, is so steep, that you may

pitch a biscuit from its summit into the river which washes its base.

The entrance of the cave is, in this side, about two thirds of the

way up.  It extends into the earth about 300 feet, branching into

subordinate caverns, sometimes ascending a little, but more generally

descending, and at length terminates, in two different places, at

basons of water of unknown extent, and which I should judge to be

nearly on a level with the water of the river; however, I do not

think they are formed by refluent water from that, because they are

never turbid; because they do not rise and fall in correspondence

with that in times of flood, or of drought; and because the water is

always cool.  It is probably one of the many reservoirs with which

the interior parts of the earth are supposed to abound, An

Eye-draught of Madison's cave, on a scale of 50 feet to the inch.

The arrows shew where it descends or ascends. And which yield

supplies to the fountains of water, distinguished from others only by

its being accessible.  The vault of this cave is of solid lime-stone,

from 20 to 40 or 50 feet high, through which water is continually

percolating.  This, trickling down the sides of the cave, has

incrusted them over in the form of elegant drapery; and dripping from

the top of the vault generates on that, and on the base below,

stalactites of a conical form, some of which have met and formed

massive columns.
 
 

        Another of these caves is near the North mountain, in the

county of Frederick, on the lands of Mr. Zane.  The entrance into

this is on the top of an extensive ridge.  You descend 30 or 40 feet,

as into a well, from whence the cave then extends, nearly

horizontally, 400 feet into the earth, preserving a breadth of from

20 to 50 feet, and a height of from 5 to 12 feet.  After entering

this cave a few feet, the mercury, which in the open air was at 50 degrees.

rose to 57 degrees. of Farenheit's thermometer, answering to11 degrees. of

Reaumur's, and it continued at that to the remotest parts of the

cave.  The uniform temperature of the cellars of the observatory of

Paris, which are 90 feet deep, and of all subterranean cavities of

any depth, where no chymical agents may be supposed to produce a

factitious heat, has been found to be 10 degrees. of Reamur, equal to 54

1/2 degrees. of Farenheit.  The temperature of the cave above-mentioned so

nearly corresponds with this, that the difference may be ascribed to

a difference of instruments.
 
 

        Blowing cave

        At the Panther gap, in the ridge which divides the waters of

the Cow and the Calf pasture, is what is called the _Blowing cave._

It is in the side of a hill, is of about 100 feet diameter, and emits

constantly a current of air of such force, as to keep the weeds

prostrate to the distance of twenty yards before it.  This current is

strongest in dry frosty weather, and in long spells of rain weakest.

Regular inspirations and expirations of air, by caverns and fissures,

have been probably enough accounted for, by supposing them combined

with intermitting fountains; as they must of course inhale air while

their reservoirs are emptying themselves, and again emit it while

they are filling.  But a constant issue of air, only varying in its

force as the weather is drier or damper, will require a new

hypothesis.  There is another blowing cave in the Cumberland

mountain, about a mile from where it crosses the Carolina line.  All

we know of this is, that it is not constant, and that a fountain of

water issues from it.
 
 

        Natural bridge

        The _Natural bridge_, the most sublime of Nature's works,

though not comprehended under the present head, must not be

pretermitted.  It is on the ascent of a hill, which seems to have

been cloven through its length by some great convulsion.  The

fissure, just at the bridge, is, by some admeasurements, 270 feet

deep, by others only 205.  It is about 45 feet wide at the bottom,

and 90 feet at the top; this of course determines the length of the

bridge, and its height from the water.  Its breadth in the middle, is

about 60 feet, but more at the ends, and the thickness of the mass at

the summit of the arch, about 40 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 lime-stone.  The arch approaches the Semi-elliptical form; but the

larger axis of the ellipsis, which would be the cord of the arch, is

many times longer than the transverse.  Though the sides of this

bridge are provided in some parts with a parapet of fixed rocks, yet

few men have resolution to walk to them and look over into the abyss.

You involuntarily fall on your hands and feet, creep to the parapet

and peep over it.  Looking down from this height about a minute, gave

me a violent head ach.  If the view from the top be painful and

intolerable, that from below is 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 is really indescribable!  The fissure continuing narrow,

deep, and streight for a considerable distance above and below the

bridge, opens a short but very pleasing view of the North mountain on

one side, and Blue ridge on the other, at the distance each of them

of about five miles.  This bridge is in the county of Rock bridge, 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 stream passing under it is called Cedar creek.  It is

a water of James river, and sufficient in the driest seasons to turn

a grist-mill, though its fountain is not more than two miles above (*

1).
 
 

        (* 1) Don Ulloa mentions a break, similar to this, in the

province of Angaraez, in South America.  It is from 16 to 22 feet

wide, 111 feet deep, and of 1.3 miles continuance, English measures.

Its breadth at top is not sensibly greater than at bottom.  But the

following fact is remarkable, and will furnish some light for

conjecturing the probable origin of our natural bridge.  `Esta caxa,

6 cauce esta cortada en pena viva con tanta precision, que las

desigualdades del un lado entrantes, corresponden a las del otro lado

salientes, como si aquella altura se hubiese abierto expresamente,

con sus bueltas y tortuosidades, para darle transito a los aguas por

entre los dos murallones que la forman; siendo tal su igualdad, que

si llegasen a juntarse se endentarian uno con otro sin dexar hueco.'

Not. Amer. II.  10.  Don Ulloa inclines to the opinion, that this

channel has been affected by the wearing of the water which runs

through it, rather than that the mountain should have been broken

open by any convulsion of nature.  But if it had been worn by the

running of water, would not the rocks which form the sides, have been

worn plane? or if, meeting in some parts with veins of harder stone,

the water had left prominences on the one side, would not the same

cause have sometimes, 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 prominences so perfectly, that, were the two sides to come

together, they would fit in all their indentures, without leaving any

void.  I think that this does not resemble the effect of running

water, but looks rather as if the two sides had parted asunder.  The

sides of the break, over which is the Natural bridge of Virginia,

consisting of a veiny rock which yields to time, the correspondence

between the salient and re-entering inequalities, if it existed at

all, has 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.