Eureka weekly sentinel. [volume] (Eureka, Nev.) 1887-1902, 1897-12-18
the FORMATIONS WHICH ARE oRf-sfAa
ING AND THOSE WHICH SEPARATE
THEM.
Adduced From the Records Of the
u. q. Geological survey OF n
Fortieth Parallel and the Personal
Research Of the Author.


I Written for tie "SentiHel" By M. III. JosePhl
Mineral Hill, which occupies the north
ern slope OF Prospect Mountain. 10 com
posed OF dolomitic limestone and granite.
4 The Prospect Mountain quartzite. whlcn
there dipping to the northeast, forms the
footwall of the Ruby Hill lode, overlies
the granite and bends around Prospect
Mountain to the east and west in the form
OF q horseshoe, trending on the east aide
to a point northeast OF and near the Eu-
reks Tunnel and on the west side to n
other point extended westward from the
Grant mine. There il sinks beneath the
surface debris, but again appears above
the mountain qusrternary just southwest
OF and near the Prospect Mountain Tun-
mel, and still further south il underlies the
Prospect Mountain limestone east OF and
near the Dug Out mine. On the east hank
OF Prospect Mountain the qusrtzite dips
to the east. The granite, which owes its
exposure on the northsrly slope OF Pros.
poet Mountain to erosion, apparently dips
under the quartzite OF Ruby Hill. Pre-
vious to the erosion, the great belt OF lime.
stone OF Prospect Mountain and that
which constitutes the Ruby Hill lode we're
presumably one and the same and formed
q continuous body. The face OF the
ouartzite dips under the limestone OF the
Ruby Hill lode at an average angle OF
about 40 degrees to the northeast. The
exposure OF this body Of limestone on the
surface extends over 1000 linear feet from
near the Albion shaft on the northwest,
where 10 10 covered BY the debris OF Spring
Valley 10 Q point southeast OF and beyond
ths Jackson mine, where 10 comes to q mar
row point or wedge between the Prospect
Mountain quartzite and Pogonfp lime
stone. On the northern end OF Ruby Hill
the limestone 10 cut off By a fault assure,
called the "Ruby Hill fault" The width
Of the limestone zone OF Ruby Hill. at the
surface. is from 800 70 1000 feet; over
lying ID on the north are the Secret Can
yon shsle and the Hamburg limestone Of
Adams Hill. Overlying the quartzite.
upon the east side Of Prospect Mountain.
is bait Of Hamburg limestone. which 10
doubtless connected 81 some depth beneath
the surface with that OF Adams Hill. In
tervening those two bodies 81 the surface,
over Q space OF about 1900 feet. Is the
Pogonip limestone. which runs in q con-
tinuous belt through the eastern portion
Of the district. from Diamond Valley,
north Of the Bullwhscker mine 10 Newark
Valley on the south. Overlying the Ham
burg limestone OF Prospect Mountain 10 q
band Of argilsceous shAle identical In char
acter with that which o~vsrlies the north
ern part OF the Ruby Hill lode. but known
- the Hamburg shAle. Nearly ell Of
THE ORE BODIES
OF considerable magnitude aud economic
value that were discovered in Eureka Dis
trict up 10 the present time we're 10 the
Prospect Mountain aud Hamburg lime
stone formations, OF the Csmbrian Age,
but valuable deposits OF ore have been
found in the ~Buliwhacker aud Williams
burg mines. which are in the Pogonip
limestone and quartz porphyry Of the ST.
lurian Age. Very rich ore has been found
In paying deposits In the mines OF New
York Canyon, in Lone Mountain lime
stone, also Of the Silurian Age. The Lone
Mountain limestone Is separated from the
Pogonip limestone by the hard qusrtzite
reef Of McOoy's Ridge. This quartzite
extends northwsrd to Csriboo Hill and
southwark to Newark Valley.
The shales and quartzites are substan-
TALLY non.ore. bearing. In some places
the Prospect Mountain quartzite in Ruby
Hill hss been impregnated with the ore
bearing solutions, but 1t has nowhere been
found OF any economic value. Rhyolite,
Q species OF the porphyry GLASS OF rocks,
igneous and Don-ore bearing. ia found in
dykes of various dimensions 10 several
parts OF the district and frequently in di-
rect touch with the ore bearing strata.
The solfatsric action consequent upon its
eruption had probably much to do with
the ascending ore. bearing solutions, il not
with the actual deposition Of the ore.
Trending southerly from the end Of the
ouartzite. ON the east side OF Prospect
Mountain, Is . belt Of Secret Canyon shale.
which separates the Hamburg limestone
from the Prospect Mountain limestone
throughout the southern section Of the
district. The Prospect Mountain and
Hamburg iimestones are identical In char
aoter In all but that the latter 10 more
silioious than the former, and il weathers
rougher and breaks with Q sharper frac-
turs. Returning to the
Ruby HILL FAULT
II il first observed northwsrd, Of the sur
face near the Albion mine, taking an al
most uniform southeasterly course, with
an average dip. underground, Of about 10
degrees TO the northeast. II passes near
the Richmond Office and IL plainly visible
near the mouth Of q tunnel that was for
merly run TO connect with the Bell shaft;
thence northeast Of she Eureka and
z K shafts 10 . point between the Phenix
ana Jee1sen mines, where 70 beads around