Eureka weekly sentinel. [volume] (Eureka, Nev.) 1887-1902, 1897-07-10
rHr FORMATIONS WHICH ARE 0af.BfAR'
ING AND THOSE WHICH SEPARATE
THEM,
Aaaueed From the Records of the
n. a. Geological survey of the
rartteth Parallel ANA the Rersonai
ue.enreh of the author.


,W,,nea for he Sentinel" BY N. ~. Joseph
Mineral Hill, which occupies the north
ern slope OF Prospect Mountain, is COM
posed Of dolomitic limestone and granite.
: The Prospect Mountain qusrizite. which
there dipping TO the northeast. forms the
footysll OF the Ruby Hill lode. overlies
tbe granite and bends around Prospect
Mountain 10 the east and west in the form
of q horseshoe, trending on the east side
A a poin, northeast Of aud near the Eu-
reks Tunnel and on the west aide to an
other point extended westward from the
Grant mine. There il sinks beneath the
surfsce debris, but again appears above
the mountain qusrterpary just southwest
of and near the Prospect Mountain Tnn-
mel, and still further south il underlies the
Prospect Noun tain limestone east OF and
near the Dug Out mine. On the east flank
Of Prospect Mountain the quartzite dips
10 the east. The granite, which owes its
exposure on the northerly slope OF Pros
pect Mountain TO erosion, apparently dips
under the quArtzite Of Ruby Hill. Pre-
yious 10 the erosion, the great belt OF lime
stone OF Prospect Mountain aud. that
which constitutes the Ruby Hill lode we're
presumably one and the same and formed
9 continuous body. The face OF the
quartzits dips under the limestone OF the
Ruby Hill lode at an average angie OF
about 40 degrees to the northeast. The
exposure OF this body Of limestone on the
surface extends over 4. 900 linear feet from
near the Albion shaft on the northwest,
where ID 10 covered by the debris of Sprine
Valley 20 point southeast OF and beyond
the Jackson mine. where ID comes TO mar.
row point or wedge between the Prospect
Mountain quartzite and Pogonip lime
stone. On the northern end OF Rnby Hill
the limestone 10 cut off by fault fissure
called the RUBY Hill fault" The width
OF the limestone zone OF Ruby Hill. at the
surface, is from 800 TO 1000 feet; over
lying II on the north are the Secret Can
yon shsle aud the Hamburg limestone oi
Adams Hill. Overlying the quartzite
upon the east side Of Prospect Mountain
10 e belt OF Hamburg limestone. which Il
doubtless connected 81 some depth beneath
the surface with that Of Adams Hill. In-
iervening those two bodies at the surface
over q space OF about 5000 feet, Is th,
Pogonip limestone, which runs in q con
tinuous belt through the eastern portion
OF the district. from Diamond Valley
north OF the Bullwhacksr mine TO Newark
Valley on the south. Ovsrlying the Ham
burg limestone Of Prospect Mountain 10 q
band OF argilaceous shale identi in char
aoter with that which overlies the north
ern part OF the Ruby Hill lode. but known
as the Hamburg shale. Nearly all OF
THE ORE BODIES
OF considerable magnitude and economi'
value that we're discovered in Eureka Dis
triet up TO the present time were in thu
Prospect Mountain and Hamburg lime
stone formations, OF the Csmbrian Age
bas valuable deposits OF ore have beer
found In the BullwhAcker and Williams
purs mines. which are In the PogoniI
limestone and quartz porphyry OF the 81
iurian Age. Very rich ore has been fourt
IN paying deposits In the mines OF New
YORK canyon, In Lone Mountain lime
stone, also OF the silurian Age. The Lon,
Mountain limestone Is separated from tn
Pogonip limestone by the hard auartzit
reel OF McCoy's Ridge. This auartzit
extends northward to Cariboo Hill an,
southwark to Newark Valley.
The shales and quartzites are substan
TALLY non.ore- bearing. In some place.
the Prospect Mountain quartzite in Rub,
Hill has been impregnsted with the ore
bearing solutions, but II has nowhere bee,
found OF any economic value. Rhyolite
species OF the porphyry class OF rocks
igneous and non-ore-besring, 10 fouud /,
dykes OF various dimensions in sewers
parts OF the district aud frequently in al
rect touch with the ore bearing strsts
The solfataric action consequent upon /,
eruption had probably much TO do viii
the ascending ore. bearing solutions IL no
with the actual deposition Of the ore.
Trending southerly from the end OF tb
quarszite, on the east side Of P:ospec
Mountain, Is belt OF Secret CANYON shsls
which separates the Hamburg iimeston
from the Prospect Mountain limeston
throughout the southern section OF m
district. The Prospect Mountain an
hamonrg iimestones are identical in cbal
acter in all but that the iattar "a -.
silicious than the former, and n ve.,ha,
rougher and breaks with a shsrnsr frs,
ture. Returning to the
RUBY HILL FAULT.
stis frst observed norlhward, a Aha m,
iacs nsas the Albion mine, iakine an 4