Evening star. [volume] (Washington, D.C.) 1854-1972, 1892-02-27
TREASURES FROM THE ROCKS.
Remarkable Curiosities ut the Geological
survey-How Mountains Are Made.

.~rNaOie Cunossues at the Geological
survey-How Mountains Are Made
TWO VERY REMARKABLE CURIosrTIES
u are placed side by side on q little shelf at
the geological survey. One is lump Of chal-
cedony as big as q child's fist, white and trans
lucent 1t is but thin shell, and when held
to the light il seen to be nearly filed with
water. which flows about as the object is
turned this way and that What makes it in
teresting 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 q drop Of il has
evaporated. Originally there was q cavity
in the rock, formed by Q volcanic bub-
BILE. Water percolated into it, bripg-
ing in solution slick, which was de-
posted on the walls Of the little hollow in q
coating Of chalcedony. At length it would
have been filled up solid with beautiful crys-
tails, forming one Of those "geodes," as they
ere called, which are natures treasure Baskets,
i iound concealed in rocky formations where
iG;ast expected and revealing wonders OF bril-
| FL. color Agates are made in the same
chnion; However, in this instance the small
becaInei by which the water flowed in and out
| cess =. Closed up In some way and SO the pro-
ten h.opped After the lapse of no one can
tainino" AZ, many centuries the stony mass con.
| contas the chalcedony chamber with its liquid
| loose. oAen open ana IL IeA ous' osins
ia vbst ner curious object above referred to
through s sps to be q petrified oyster, cut
half she'll INA mat one sees 1t apparently on the
| frosb for Just as 1t would look when opened
,resh tor customer 1t was found in chalk
| peos iornleo largely of the shells of various
amorg tbsm NY many oysters and clans
sniu1 'nJ hich me so,called .'heart' of the
1 II lto
other parts are WONDERFULLY dist;nc. N rha-s 10
| even small pearl in it seeminolv yet IL IA
not an oyster at all, but merely ono ~ thoss
marvellous imitationsi which nature makes Of
her own works in freakish moods Ae' Va
| The government rock sharps find ,,
surprising curiosity among the rocks wh;aE -
| is their business to investigate Inst no,. .,
the Office of the geological survey thew are ca a.
gagged in building imitation mount ains for tbe
purpose of studying the way in which the
| to the contraction o. the earth's crust The
| coal basins and other valuable mineral deposits
| in many parts of the United States have under
| gone just such crumpling. SO that it will be
profitable to ascertain the laws governing it.
These imitation mountains are built of wax,
hardened or softened by mixing it with other
substances, SO that it shall resemble in con-
| sistency the brittle 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 cas-,
in layers of a given thickness by melting and
| flowing it in q 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, repre-.
| senting geological strata. The next process II
\ to place the layers in a machine, piling sho,
on top of them to represent the force Of gray
| ity, after which pressure is applied from the
ends very slowly by piston advanced with .