M'arthur Democrat. (McArthur, Vinton County, Ohio) 1853-1865, 1859-03-31
Geology.

Geology.
We do not intend under this head
to give lecture on Geology, but a
few simple definitions that will fire.,
quently aid the readers Of agricultur,
al papers.
SoIL.--The ingredients of the sol
are derived from the decomposition oil
rocks. This decomposed rock is call.
ed debns.
RoCKs,-are classed as primary,
Chose created with the earth and
secondary, Chose since found;) J this
last class OF rocks is divided inlo up
per and lo'cer secondary. There are
also other formations, called metam0r
lphic and intrusive; the first, when the
primary approaches to, and appears
to be passing into the secondary; the
latter is class of rocks common to
both classes, that intrudes into others
without any regular order. These
classes lie in regular order, the prima.
ry never above the secondary, nor the
secondary below the primary; thus,
coal is never found below the pri-
mary rock, though it sometimes rests
on it.
GRANITE.-This is the primary and
lowest rock in the series, and is me-
chanical mixture of quartz, feldspqr
and mica. Hutton the author of the
Huttonian system, ,supposes GRANTEES to
have been fused by central heat. and
in liquid state to have beer hove up
ward. Werner author of the Werner
ian system, supposes it to have been
the earliest aqueous formation, or de-
.posit. The particles Of quartz, field.
spar and mica composing grants are
cemented together, forming rock with
out strat:fication, which will break
but not split.
FELDsPAE.-Feldspar, which is one
OF the ingredients of granite, is COM
posed of silex, 62 parts; alumina, 16;
potash, 13; lime, 3; oxide OF iron, L.
When pure and decomposed, it is call. .
ed kaOJin, and is porcelain clay, of
which queensware and porcelain teeth
are manufactured.
MICA.-Mica another Ingredient of
granite, commonly called isinglass, in
a pure state, is transparent as glass,
splitting into thin plates. 1t is com.
posed OF slick, As parts; alumins, "a;
potash, Is; oxide of iron, 5.
QUARTz.--Quartz, the other ingre.
dent Of granite, is almost pure silex,
So that granite contains within itself
almost all the ingredients of a good
soil, and if pulverized, would form
an excellent manure. Whether it will
ever pay to be prepared for manure
may be doubted; but as its use for
manure would remove it from where
it is a nuisance, we would like to see
the experiment tried.
NEIss.--Gnoiss is formed of the
same materials as granite, generally
in fine divisions, but so arranged as
to be stratified, and split in one direc.
tion only. 1t is aspecieS of aggrega.
ted rock, composed Of quartz, leldspar
and mica, and is more or less slaty.-
The lapers, whether strait or curved,
are often thick, and vary in the same
specimen. 1t passes on one side III
to granite, and on the other into mica
slate. 1t often contains hornblende,
and only iffers from granite n its sla
ty and stratifiod formation. 1t is
placed Immediately above granite aud
appears to be only a modification of
it in strata.
MICA SLATE.--This enters largely
into the composition of gnejs8, and is
composed Of mica and quartz
When the quartz predominates, it
passes into quartz rock; when the
mica predominates, it will split into
thin Ianain@, or slabs, and makes ex.
cellent paving stone.