The great West. [volume] (St. Paul, Minn.) 1889-18??, 1892-04-15
TREASURES FROM ROCKS.
Curiosities at the Geological Survey-How.
Mountains Are Made.

TREASURES FROM ROCKS.
curiosities al the Geological survey-How
Mountains Are Made.
Two very remarkable curiosities
are placed side by side on a little
shelf st the Geological Survey says
The Washington Post. One is lump
of chalcedony as bigas child's fist,
white and translucent It is but q.
thin shell, and when held to the light
is seen to be nearly filled with water.
which flows about as the object is
makes it interesting is that the water
has undoubtedly been inclosed and
Theoretically sealed in this natural
receptacle for thousands and thousands
of years. Probably it was there long
before Moses was born. and yet not a
drop of it has evaporated.
Originally there was cavity in the
rock. formed by a volcanic bubble.
Water percolated into it. bringing in
solution SLICK which was deposited ON
the walls of the little hollow in a
coating of chalcedony. At length it.
would have filed up solid with beauti-
full crystals. forming one of those
'geodes " as they are called which
are natures treasure caskets found
concealed in rocky formations where
least expected and revealing wonders
of brilliant color. Agetes 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 CEN
turtles the stony mass containing the
chalcedony chamber. with its liquid
contents was broken open and it fell
out being loose.
The other curious object above re-
ferred to is what appears to be pet
rified oyster. cut through SO that one
sees it apparently on the half SHELF
just as it would look when opened
fresh for customer. It was found
in the chalk beds formed largely of
the shells of various bivalves, prob
ably many oysters and clans among
them. The so-called heart of the
animal. which is its big muscle. and
all the other parts are wonderfully
distinct. There is even a small pearl
in it seemingly. Yet it is not an
oyster at all. but merely one of those
wonderful limitations which nature
makes of her own works in freakish
moods
The government rock sharps find
many a surprising curiosity among
the rocks which it is their business to
investigate. just now at the Office of
the Geological survey they are en-
gagged in building imitation mount
aims for the purpose of studying the
way in which the eternal hills were
formed by the crumpling due to the
contraction of the earth's crust The
coal basins and other valuable miner
al deposits in many parts of the
United States have undergone just
such crumpling, so that it will be
profitable to ascertain the law govern
ing it.
The imitation mountains are built
of wax hardened or softened by mix
ing it with other substances, so that it
shall resemble in consistency the brit
tie rocks near 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. as the case may be.
The mixture is cast in layers of n
given thickness by melting and flow
ing it into a wooden trough. When
each layer has hardened it is taken
out and a number of the layers thus
made are superimposed one upon the
other like layers of jelly cake. repro
senting geological strata The next
process is to place the layers in
machine piling shot on top of them
to represent the force of gravity. after
which pressure is applied from the
ends very slowly by a piston advanced
with screw. This causes them to-
crumple up and under the artificial
contraction they are found to take pre-
cisely the forms of mountain ranges
like the Alleghenies.