Custer chronicle. [volume] (Custer City, Black Hills, D.T. [S.D.]) 1880-1890, 1885-10-17
The Mines Around Custer.
CONTINUED nom eur last


bottom Of an inland sea, and the
archean slate was the foundation rock
that this sea, like all other oceans, had
its currents aud counter currents that
rivers running down from lands OF
higher altitude flowed in TO it; that
these rivers held and carried in suspen-
sion the sediment that went to make
up all the different stratas whose edges
are now laid bare in many places, hav-
ing been cut by the flow Of rivers while
the stratas were yet soft and before they
were hardened BY age and action Of the
atmosphere. We refer now to the sedi
mentary formation as it was laid down
horizontally on the floor of the old or
archean slate. All this was not done in
a day, but required ages, and it is with
reference to these ages that geologists
classified the stratas as the silurian,
devonian, carbonaceous, cretaceous etc,
deriving their data from the fossils, or
remains of the different worms, fish, or
animals that have made each strata
their home in the age in which they
lived.
The first laid down or deposited, was
the old, coarse, gray sandstone, known
as the Potsdam sandstone; on top OF
this came the siliceous slate and con-
glomerate then the shales, then the
limestone, and 80 on. But we will 20 no
further than the limestone, as that is
the highest formation We find in the
Hills, or the mineral portion of the
Hills, and If this was ever capped by
any other formation, (and it is presum-
able that it was) it has long since been
worn and washed away. Now, suppos-
ing all this to be 30 as the facts indicate,
and our scientists all agree upon it, we
will shit the scene and introduce the
next act in the worlds great drama.
And now, what do We see? There is a
great commotion i'm the water the floor
Of this ocean is swelling and rising; the
water begins TO recede, and the dry
land appears above the water. The fish
are disturbed, and many Of the reptiles
and submarine animals are stranded
and left high and dry. If any Of our
| readers want to see some Of these re-
mains, they can go out to the bad lands
ESQ called, although that land is rich
enough TO be used az a fertilizer for the
lean lands Of the east and pick up their
petrified bones by the wagon load.
Now the earth begins to crack and open,
and along the line of these cracks comes
issuing steam and hot water, and next
comes oozing up, and filling all these
cracks. In the northern portion Of the
Hills with substance which we call
porphyry, and in the southern portion
comes yelling up a different substance
which we call granite, and in the cen
tral part a still different substance
which we call gneiss. These, the granite,
gneiss and porphyry are what the geolo-
gists term igneous or fire made rocks,
as distinguished from the sandstone,
| limestone, and shales, which are termed
| the sedimentAry or water made rocks.
| These igneous rocks (so called are sup
| posed to be the source of the mineral
| for the reason that in their absence We
| find no mineral, and in their presence
we always find it. Yet, strange to say,
we do not, as a general thing, find the
| mineral in the rock itself, but in fissure
cracks or veins running through these
| rocks in quartz, or in veins either fissure
or bed veins in the country rock, but
always near to or in contact with one OF
these dykes or ridges Of one or the
other of these igneous rocks.
1t might seem to some that in the
foregoing that We were DEPRESSING from
our subject, but we are not; we are
treating Of the mines Of Custer county
all the time, only thus far our vein sys.
tenn having common source with the
grand upheaval Of the country, we could
not make ourselves plain without treat
ing on the whole vein system of the
Black Hills. But now we come to q
point Of difference, for in the northern
Hills we find the igneous rocks to be
porphyry, and in the southern Hills we
have the granite, but no porphyry,
while in the central Hills the igneous
rocks is gneiss, without either granite
or porphyry, save here and there where
it meets and blends with the granite on
the south and the porphyry on the north
Spring creek, which is about IL miles
north Of Custer, seems to be the norther
ly boundary line Of the granite up
heaval, and il is to the mines in and
around this formation that the reader,
attention is now called, for it is in this
formation, the world over, that tht
greatest variety of minerals are found
1t is this formation, the world over, thai
is most noted for true fissure veins anC
it is in this formation that the pros
pector is most liable to find his high
grade ore. 1t is but fair to state how
ever, that this last remark will hardly
apply to silver, though it is laid down
in the books that the place 10 look fol
the richest silver is in the small veini
in the slate, in contact with granite, but
the result of our experience and obser