Mineral Point tribune. (Mineral Point, Wis.) 1869-1938, 1892-05-14
TREASURES FROM THE ROCKS.
Remarkable Curiositics at the Geological
sGrvey-How Mountains Are Made.

Two very remarkable curiosities are
placed side by side on little shelf at
the Geological Survey. Oue is - lump
ui chalcedony as biz as a child's iSt,
white and translucent. Ii is but a
thin she'll, ard when held 20 the light
is seen to y, nearly filled with water
which flows about as the object is
turned this way and that. What
makes it interesting is that the water
has undoubtedly been iuclosed and
Theoretically sealed in this natural re-
ceptacle for thousands and thousands
of Years Z obably II was there long
before Moses was born, and vet not .
drop of il has evaporated. Originally
there was cavity in the rock. formed
10y volcanic bubble Water percolat-
ed into it, bringing in solution slick,
which was deposited on the walls of
the little hollow in coating of chal-
cedony. At length it would have
been filled up solid with beautiful
crystals, forming one of those "geodos,
as they are called, which are natures
treasure Baskets, found concealed in
rocky formations where least expected.
and revealing wonders of brilliant
color. Agates are made in the same
fashion. However in this instance
the small channel by which the water
flowed in and out became closed up in
some way and so the process stopped.
After the lapse of no one can tell how
many centuries the stony mass con-
tanning the chalcedony chamber with
its liquid contents was broken open
aud it fell out. being loose.
The other curious object above re-
ferrcd to is what appears to be petri-
fed oyster cut through so that one
sees it apparently ON the half-shell,
just as it would look when opened
fresh for customer. 1t was found I'm
chalk beds formed largely of the shells
of various biySlYes, probably many
oysters and CLANS among them. The
so-calleG heart Of the animal. which
is its big muscle and an the other parts
are wonderfully distinct There is
oven a small pearl in it seemingly. Yet
it is not an oy ster at all, but merely
one of those marvellous limitations which
nature makes of her own works in
freakish moods.
The government rock sharps find
many a surprising curiosity among the
rocks which il is their business To in-
yesLgate. just nov n the office OF the
geological survey they arc engaged in
building imitation mountains for the
purpose Of studying the way in which
the eternal hills were formed by the
crumpling due to the contraction of
the eartb's crust The coal basins and
other valuable mineral deposits in
many parts Of the United States have
undergone Just such crumpGng, so that
it will be profitable to ascertain the
laws governing 1t.
These imitation mountains are built
of wax, hardened or softeued by mix
ing ii with other substances, So that it
shall resemble in consistency the brit
Tie rocks uear the surface Of the earth
or the plastic rocks which are in that
condition because Of the great pressure
that exists even at depths of only two
or three miles, IS the case may be.
The mixture is cast IN layers Of a given
thickness by melting aud flowing il in
"a wooden trough When each layer
number of the layers thus made are
superimposed one upon the other, like
layers of jelly cake, representing
geological strata. Tho next process is
60 place the layers in a machine, piling
shot on top of them TO represent the
force of gravity, after which pressure
is applied from the ends very slowly
by piston advanced with screw
This causes them to crumpic up, and
under the artificial contraction they
are found to take precisely the forms Of
mountain ranges Ike the AlIeghenies
- washington Ntar