The Democratic press. (Eaton, Preble County, Ohio) 1860-1865, 1861-12-19
Written for the Democrats kress.
EVENINGS AT HOME.
BY AUNT MARY.
II.

I'VE are quite ready, Aant Mary,I
to hear something more aEopt theE
earth. We are quite caops to-
know what creatures coa|a have
lived on the earth bsfers i'm wat
created..a
d Undue time. -safs
must first introduce you to the
long words I spoke of last evening,
that you may become acquainted
with the classification and nomen-
clature of the various strata. |
have already told you that the
three divisions, called by geolo-
gists, primary, secondary and ter
tiary, are founded on the supposed
chronological order of their crea-
ton. These have been subdivided
into separate formations, some Of
which are named from the most
prominent rock of which they are
composed. 1t will not be neceSsa-
ry for you to commit these subdi-
visions to memory now, as we shall
allude to them so frequently, in the
course Of our conversations, that
you will become sufficiently famil-
iarized with the order Of their sue
cession for our present purpose.
The tertiary formations, divided
into Upper, Middle and Lower,
contain the Pliocene, Miocene and
Eocene strata, extending at the
point of their greatest known de-
velopment, about $50 feet below
the surface of the earth. The Sec
ondary also subdivided into Upper,
Middle and Lower, contain the
Cretaceous, Oolitic and Triassic
systems; these extend about 5000
feet in depth. Between the sec
ondary and primary -rocIsss2ie the
| Transition series, which contain
the carboniferous or coal systems,
> also metallic ores; thickness from
1000 to 5000 feet. The primary
: formations contain the Plutonic
and Metamorphic series, consist
ing of GRANTEES, states and crystals
. the depth of which has not been
yet ascertained but is supposed tC
y exceed two miles
is all the granite that is usc(
for building bridges and othel
structures, dug up from below al
the other rocks, Aunt Mary?'
No, my dear Fanny, granite il
i often found detached and near thu
surface of the earth, but is novo
found lying on any rock in a STRAIT
: flied form, ard is therefore consid
cred to be the foundation WHEREOF
all the Others rest
Then the various strata are no
s. always found lying upon each 9th
{ er in the regular order in whicl
5 you have named them?'
g No, my dear, if they were, tn
Il study of geology would be yer,
u easy indeed, supposing the eartl
y could be bored to a suficien
10 depth to investigate the entire SC
. ries of strata, but the thickness G
10 many of the strata is SO great, tina
= we should probably have to pene
n trate to the depth of ten miles be
l0 fore we reached the granite, an
g such depth, or any approach to i
ie is altogether unattainable. Whe
~ rocks are found in successive strat'
Us according to the arrangement
I, Fhave just given you, it is terme
d 'conformable stratifcation:' whe
T. either the position or inclinatio
oi of the strata is disturbed, it PR
u sents an uncomfortable stratifici
d ton"
4 suppose volcanoes and eartl
III quakes have disarranged the orig
3o nal conformations?
Yes, my dear Anna, these a
= some of the disturbing cause
oe Eruptions of igneous matter ha'
covered the tops of the loftie
% Of mountains, and have dislocated
ce removed the solid strata; the m
to, chanical action of water has swe,
ro no away entire beds ofrocks, and d
ev posits of rivers and former lax
have superposed local formation