Staunton spectator. [volume] (Staunton, Va.) 1849-1896, 1859-09-27

Far. the Spectator.
Agriculture of Augusta County.
SECTION III.
Geology and Formation Of Soib.-The rock
masses forming the basis upon which August
county rests, are generally strsti6ed, and presen
considerable variety in structure and compost
ton. Hence the soils formed by their disinte
grafton vary widely in condition and quality.
In presenting brief and general outline o
the geology of the county, We shall commence a
the top of the Blue Ridge, which forms its s. E
boundary. The whole area may then be conve
niently divided into fpe distinct belts.
1. The first we shall call the "Blue Ridg'
belt" This lies along the s. E. border Of tbs
county, extending in length from the Rockbridgt
summit of the Ridge to the beginning of the
limestone rocks along the 8. River valley. The
main ridge OF this mountain range is composed
largely Of unstrati6ed or igneous rocks. These
were not deposited by the action of water, like
most of the rocks of this county, but have beer
thrust upward through the everything strati6ed
masses, by volcanic forces, and in fused condi
tinn They consist chiefly Of Trap and Epidote
minerals which by their dlsulegratiun mske
good soils. These are the only igneous rocks
found in Augusta, except an occasional dyke o.
Trap, which is found protruding here aud there
through the limestone rocks of the valley
When these Trap dykes are exposed to the wealth
or, the rock breaks up into angular blocks of va
rious sizes, which soon become weather-worn
having their angles rounded, and assuming the
shape of water. worn boulders. They are called
''irop rocks" it being enormously supposed, from
their weight and dark brown color, that they
are iron-0rs. Some call them "6re rocks, from
the fact that they bear high temperature with
out much change Of condition. On this account
they are used for lining lime-kilns. There is q
Basaltic Trap dyke near Mt. Solon, in which
short, black crystals of the mineral hornblend.
are abundant.
Near the Rockbridge line the igneous masses
of the Blue Ridge are very extensive, and by
their elevation, have thrust the adjoining sand
stone and slaty strata, forming the broken ridges
and spurs of the western slope of the mountain,
further out towards the valley, than at any 9th
er point in the county. The consequence is that
the limestone portion of the valley is here con-
sderably contracted and the rocky strata press.
ed back into an almost perpendicular position,
as may be seen near Midway and Greenvlle.--
AS the mountain approaches Rock6sh Gap, the
igneous rocks diminish in extent, until we find
at the Tunnel, the main ridge composed chiefly
of stratified rocks, which belong to the eastern
slope OF the mountain. Farther north the igne
ous rocks again increase in extent had give great
elevation to the sandstones and states resting a.
gainst their western side.
That portion of this belt lying between the
Blue Ridge and the valley limestones is made up
of the sandstones and states already alluded TO-
The strata here have been elevated on their
eastern edge by the igneous rocks so as to give
them western dip (or downward slope;
though, in some cases, they have been not only
elevated, but have been thrown back and tilted
until the eastern edge leans toward the west
aud the dip is towards the mountain. An ex-
ample of this may be seen near Waynesboro'.-
The states of this formation disintegrate rapidly
and form deep beds of clay, the soils of which
have moderate degree Of fertility. The sand
stones have been broken down more slowly, and
whilst much of the material of the states has
been carried off by freshets, the former rocks
still form the crests and bold precpces Of the
numerous knobs and peaks which give so much
of both beauty and sublimity to the western
slope of this dividing range OF the two Virgin
ias-two, yet one.
2. The next belt is one of limestones. These
have been very much worn down along the 3
River valley by the immense freshets that hsv'
swept down from the neighboring mountain
gorges at some former period of Geological His
tory But where they are exposed to view q.
long the bed, or on the banks of the river, the.
are found in nearly perpendicular position
Sometimes dipping eastward and sometime
westward. These lime-bearing strata lie g.
bove the adjacent states and sandstones in tn
geologic series; /. e., they are newer rocks, hav
isg been deposited in an ancient ocean, of which
tue others formed the bottom. The western
limit of this belt is a peculiar slate formation
stretching from three or four miles below Green
vile to the Rockingham line. 1t is about 81,
miles wide where the Central R. R. crosses 1t
and becomes narrowed down to less than fou
miles as it approaches the county line near Wey
| er's Cave. 1t also becomes narrower toward
its southern extremity, being compressed by tn
vast mass of matter thrown up in the Bule Ridg
opposite this part of the valley. This belt con
sists not only of vast beds of solid lmestones, bu
also of extensive layers of oalcareous shales,
which crumble down, under the influence Of tn
weather, with much greater rapidity than tn
more solid rocks. In many parts OF this bel
heavy beds of finty rock are found. Thi
rock is sometimes white, but more frequently G
blush gray, and brown color. 1t is wor
down more slowly than most of the neighborin
limestones and shales, and is hence left standin
up to form the central mass of numerous peak
and ranges of hills. 1t is gradually broken b.
the weather Especially the rain and frost int
fragments varying from minute grains OF san
through every possible size, up to rocks OF man
tons weight. These are frequently strewed o
YER the whole faces of hills, covering up to
great extent the more valuable cays formin
the lower slopes. The belt DOW under conside
ration has double range Of hills OF this charst
ter lying along its western side, little east
N. Hope, Fishersvlle and Barterbrook. Th
strata of more than half of thi, belt have wes
ern dip, by which they pass beneath the slat
belt next to be described.
8. The third division Of the geological feature
of the county embraces the slate belt above al
luded to. This does not, like the others, exten
throughout the whole length of the county. W
find its s. W. extremity, about tour miles nort
of Greenville, on the farms OF Messrs. fiisor
Shields, Christian and Others. The boundar
here is somewhat irregular, and the width aoou
mile. From this point it runs nearly parali.!
with the general bearing of the mountains IN
35 deg. e. until it passes into kockicgnal
county. 1t spreads out gradually until it attain
width OF about FIVE miles at the place wher
the Railroad crosses it between Staunton an
Fishersville. The width then varies but litti
until it approaches the Massanutten range :!
mountains in Rockingham. Passing under thi
range, it forms the basis upon which It rests.
In the middle part of this belt the states stan
upon their edge. Along the eastern and wester
sides they dip towards the middle. In tact I'd
whole formation lies in basin OF limestone rock
which crop out on both sides. The lower STRAIT
of the slate lie parallel with the bottom OF thl
basin, and also crop out on both sides OF tn
belt. So great has been the sinking in the mid
die, and the lateral pressure in that direction
that the highest strata have been folded an