The Helena independent. [volume] (Helena, Mont.) 1875-1943, 1893-05-20

been yery large indeed. and has gone q
krOgs distance. IL consists here. ~ II does
evury whore else, In the creation OF new
minerals ont Of the, old materials. The
gfsnttes and ths states exchange elements
70 some sxtsnt. and out OF the ordinary
clay slate ONE a mica sehist with mica Ia
u. which Was not tn the slate bsfots. AL
though the ingredients wee there. Ono of
the char CITE Of the rock ID garnsts.
The contact e0sot Of granite with clay
slate IL generally to take Of II it's fslspar
almost to nothing but quartz and mica.
Another spsoimen OF altered granite az the
contact yaa exhibited 10 tho jury. DR..
Raymoaa said y was very instructive. II
was taken from tho IT. Louis
shaft No. J, which shows tho granite
twenty feet down and slate under II. Tho
granite has been hsraotsristioaliy altered
In the shaft until = person would hardly
now Il to DO granite. except that. bunohes
of tho mica slate could be found which
have been left there. Tho specimen also
showed the alteration In the slate. DIR.
Raymond said !: did not look a bit like the
ordinary clay slate. but that 1t was shiny
and crystalline and had received from the
g. ante some exchange of minerals which
formed tho new structure. He said those
contacts usually deoolorixe the etuptive
rock. the color 10 withdrawn from it, and it
mstamorpnossa; but ii IL known 10 DO
granite by tho nature Of the quartz and tho
appearance OF the patches OF mica In it.
The piece he exhibited hs said was taken by
himself from the crosscut at the bottom Of
shaft No. l running almost vertically under
the granite contact above. He snld it WAS
effect upon which of the contact IL shown
by IN intense solidiaoation. great hardness
and solidity OF tho rock, making II look
like a black dyke material and
not like thu ordinary slate. He
showed another specimen from the Same
formation which he said was a better SAM
pie. II was taken from o la &c quantity of
tho same stuff which was last thrown out
upon the dump of the shaft. The doctor
said he observed a great doal of what was
called BY @. Il. Batterman, Of Colorado,
the st. Louis compsny's export, "incipisnt
garnet" The doctor thought II WAS q very
happy phrase. but no was not quite sur
but they ara there. Thoy are not olenr like
the crystalline garnets used for jewelry.
The general mass of the rock seemed to
him to be a horn blende sohist, some mag.
nesia; II is not soapstone. 1t is what Prof.
CLAYTON used to call IAN impure serpen-
him. II 10 not soft enough. He showed
another piece exhibiting tho same ~altera-
ton of the slate. He said il was very diff
omit, and one might say improper. to give a
definite rock name to q product like this.
which ia really tho transition from one
md looks like a mica schist. 1t is tho
reorystallized slate affected by the contact.
Two specimens were next exhibited which
came from the 400 level Of the Drum Lum-
mon. Close by the pump station of shaft
No. 2. the doctor said. and proceeding
south along the foot wall from that shaft
there ID a considerable exposure of granite.
First there is a regular, complete granite
there. and close by it and along with il are
the states which have been acted upon by
the granite. This, he explained further on.
Is q tongue of gtanite extending from the
main mass In the m~ountAin-the nucleus
granite; here 1t has altered the states in it's
type of slate shown to the jury. more or
leas crystals. not at all like the old-fash-
Toned clay slate. In examining to sec
whether it WAS a tongue OF granite the doc
tor procured a specimen tom the contact
rock 600 feet under the ground. The piece
tho same time slate-a contact piece. This
sample with another he said were conclusive
evidence. although not as good as he would
like to have. that the granite which he had
observed 10 really the face of a granite
tongue coming from the mountain.
Next he 81 Explained what one of tho law
yers oallod "the intrusion of tho granite
into the slate" He said 1t must not be
supposed that the granite lifted tho states,
or crushed them. or exercised any particu-
lar direct mechanical effect upon them,
because the granite. according to tho best
deductions, must have been in the form Of
a paste. like freshly mixed mortar. The
slates we're lifted by some side thrusta, not
fully explained, but which is generally sup
posed to be duo from the contraction of the
earth. The doctor said it would AXE from
1900 to $4,000 feet of rock lying over the
granite to permit it to crystallizs in the
form in which IL ia. He said he did not
geological explanations, but it might be
interesting to say that ono of the reasons
for that deduction was the presence
in the quartz crystals of the granite of
liquid carbonic acid. which could not
have been liquid except under such a pres
In the quartz crystal Of granite IL ia settled
at once that the granite must have crystal
lizsd under great pressure. The granite be-
ing under the pressure OF the superincum-
bent rock comes up into any hole or cav
ity or crack or opening that IL made by the
States. When such q mass of states il
pressed by side thrusts there is IN opening
there and the granite simply follows after,
just as water would in any hydraulic ma
chine; it would 40 wherever il could, and
the weight of the surrounding rock being
upon the granite. Is filled up all the holes.
That is why granite 10 found entering into
all OF she states. The states didn't do any
thing, They were lifted. and whatever
hole there was became filled by the granite,
and II IL was q small crack the granite
could still force its way in. Some OF these
tongues of granite are bulbs on the end of
some channels of granite. Some Of them
have since been cut off by slips in she rock,
faults az they are called, not The large
Ones. but the little slips which
dislooate only n few inches or
a few feot. Afterwards when it
came to the action OF Ourfaoe waters these
Fragments got rounded on the corners and
nre then called bouldsrs. The doctor said
they were not boulders, never were, and
trusious. The outline 10 necessarily very
rugged OF the contact, he said, by reason
of tho granite going everywhere there
was room for it, and there was a good deal
of room, owing TO tho breaking of the
states by this upheaval. On the surface it
IL irregular for two reasons. In the first
place, u 10 irregular because 1t ia only a
limo. II 10 not a line Of great Importance;
it ID a line Of accidents. II is a line just
wherever the erosion OF tho surface has
happened to stop. Tho slate was origin
,ubbed off now. and whore it il rubbed off
and tho granite 10 exposed, usually in u de-
preston. because the granite becomes de-
composed there, an irregular line is pro-
ducsd. II a little more is rubbed of the
limo of contact 10 changed. The other rea-
son for irrssulatity on the surface is that
when a ravine has been bitten out. that will
necessarily throw the limo Of outorop back
into the ravine. Next he explained the ir-
regularity underground which makes tho
granite protsude into the slate and then