Dodgeville chronicle. [volume] (Dodgeville, Wis.) 1862-current, 1865-07-06

IDENTIFY stone-mad.
with this hammer, my boy, I break
my way into the treasury of Nature"
Here Boulder brought his hammer
down, and smashed my tea-cup.
"Ab, good !" he cried, taking frag-
ment up. "a lucky accident Look at
the crystalline fracture. What's here?
Clay. What makes the clay crystalline
in its fracture? Fire. Theory Of the
igneous rock. Thickness of the ponder
able crust of the globe, eight hundred
miles. Depth at which most of the rocks
ordinarily found at the surface would ex-
ist in molten state, say fve-and-twen-
ty miles. Undercrust of the globe,
granite Here's bit"
My excitable friend took from the
mantel-piece handsome paper-weight
If polished stone.
'Some ass Of a man has polished this
fine specimen ofprimitive rock" With
one tap Of his hammer, Boulder broke it
in two ."Observe, he said, ''the cx-
quisite fracture"
"Exquisite-co confound-"
"Never polish fine specimen. The
geoogist, my dear boy, is most particu
lar to show you a clean fracture and
nothing else. He breaks stone, and
takes pains not so much as to dim with
fingers touch the brlliance Of the
broken surface Now fractures are Of
various sorts, conchoidal or shell like,
even, uneven, smooth, splintery, hackly.
Only look in this beautiful bit Of gran
ite, at the silvery CLEANS of the mica
and the suety bits Of quartz speckling
the solid pudding Of felspar. Quartz is,
Of simple minerals, one Of the hardest
| knock out little chip of the granite,
and you will observe that it is impossi-
bic to powder the quartz in it by the
blows of hammer on the hearth-stone
You perceive the hearth stone breaks,
but the quartz grains remain uncom-
minuted.
'.Mr. Boulder I began, family
[ was made somewhat weak and help
less by my cold, or [ should have met
vigor with vigor.
Pardon me, Smith they remain, |
say, uncomminuted Let me advise you
to be a geologist I am going to the
hills day on an excursion. Come
Ah, you have cold. Well, I will stop
exactly half an hour" Here he pulled
out his watch. Il do want you to share
my enjoyment. | do want to make you
feel the delight caused by the study Of
geology. | didn't think that | should
take it up myself when | turned out
Jacks drawers. Page over-persuaded
me. He's just the man to bring the sci
ence home to you. All, Mrs. Boulder
doscn't know it, but I've carried up her
spare sheets and blankets into one of the
attics and have most beautiful exper-
iment on the formation Of mud banks
from aqueous deposit in her linen chest.
I've mixed up in water earth and shells
and shilling's worth of shrimps. In
a few days, when | drain the water off,
you come over to me, and I'll show you
how the top crust of the world is formed.
and how the remains of extinct animals
get to be mixed with it. Only. if Mrs.
B. should by chance go to the chest be-
fore the experiment is fnisbed-O those
women those women
"But now, Smith, as you've a cold,
and can't 90 to the hills, III show you
how geologist need go no farther than
his own room for study ofimcomparably
the most glorious of sciences. I'll give
you to-day only an elementary lesson
When [ come next we'll 90 into the
thing more completely. Now look here"
down came the hammer on a corner Of
my mantelpiece,-"I break of this lit
tie Bit of metamorphic rock; the char
acter has been destroyed by polishing,
but now what beauty have | not reveal
ed.'
Boulder l cried, '.g,ve me your
hammer Let me send your hammer
down into the hail. F"
"Thank you, thank you--I shall be
going presently. 'Tis not worth while.
Dismiss from your mind what | was just
saying about aqueous rocks. Above the
igneous you have the metamorphic--you
have, to speak familiarly, the mantel-
piece upon the paper weight, and not
the, paper weight upon the mantel-piece." !"
II have, have I?''
''To be sure you have. Heat and the
psessure of the superintendent strata
have given to these metamorphic rocks
their crystalline appearance, though 1t is
believed that they were once deposited
by water, and contained fossils of which
all trace bas been extinguished. Well
then, Smith, on the top Of the metamor-
phic rocks, on the top of the mantel-piece,
we place Ser Roderick Murchison. ,
"Can it possible p
"Yes. Murchison and the Silurian
rocks defined and discovered by him
They used to be called, along with some
others, the Greywacke formation"
30, indeed !"