Eureka weekly sentinel. [volume] (Eureka, Nev.) 1887-1902, 1897-07-31
rNf FORMATIONS WHICH ARE oRf-sfAR'
ING AND THOSE WHICH SEPARATE
Them,
Adduced From she Records of she
n. n. Geological survey of the
Forsieth Parallel and the Personal
Research of the Author.

n. n. Geological survey of the
Forsfeth Parallel aod the Personal
eareh of the Author.
fWr,tt,n for ne Senfinsi" BY N. II. Joseph ]
Mineral Hill, which occupies the north
arm slope OF Prospect Mountain. 10 COM
posed Of dolomitic limestone and granite.
: The Prospect Mountain qusrizi.e. which
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 a horseshoe, trending on the east side
10 a point northeast OF and near the Eu-
reka Tunnel and on the west side 20 an
other point extended westward from the
Grant mine. There IL sinks beneath the
surface debris, but again appears above
the mountain quarternary 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
20 the east. The granite, which owes Its
exposure on the northsrly slope OF Pros.
pect Mountain 10 erosion, apparently dips
under the quarizite OF Ruby Hill. Pre-
vious TO 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
quArtzite 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 II 10 covered by the debris OF Spring
Valley 70 point southeast OF aud beyond
the Jackson mine, where 10 comes TO o mar
row point or wedge between the Prospeci
Mountain quArtzite and Pogonip lime
stone. On the northern end OF Ruby Hill
che 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 IL on the north are the Secret Can
Jon shale and the Hamburg limestone OF
Adams Hill. Overiying the qusrtzite.
upon the east side OF Prospect Mountain,
is q belt OF Hamburg limestone. which 10
doubtless connected as some depth beneath
the surface with that OF Adams Hill. In
tervening those two bodies At the surface.
over Q space OF about 5000 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 Bullwhacker mine to Newark
Valley on the south. Overlying the Ham
burg limestone OF Prospect Mountain is
band OF argilaceous shale identical In char
acter with that which overlies the north.
ern part OF the Ruby Hill lode. but known
o. the Hamburg shale. Nearly all OF
THE ORE BODIES
OF considerable magnitude and economic
value that were discovered in Eureka Dis
triet up 10 the present time were 10 the
Prospect Mountain and Hamburg lime
stone formations, OF the Cambrisn Age.
but valuable deposits OF ore have been
found In the Bullwhaoker aud williams
onre mines. which are In the Pogonip
,imsssons aud quartz porphyry OF the ST.
,ufiAn age. Very rich ore has been found
~ paying Deposits in the mines OF New
iolh osnyoh, In Lone Mountain lime
stone, also OF the silurian Age. The Lone
moun'Ain limestone IL separa ated from the
fogonip limestone by the hard ouartzite
reel OF McCoy's Ridge. This ouartzite
extends northward to Cariboo Hin ana
sonthward TO Newark Valley.
The shales and quartzites ara substan.
nsliy non-ore- bearing. In some plaees
tne Prospect Mountain quartzite In Ruby
Hill has been impregnsted with tbs ore.
bearing solutions. but ID has nowhero been
found OF any economic value. Rbyolite
species OF the porphyry class OF rocks.
igneous and non-ore. bearing, is found In
dykes OF various dimensions In sevarsl
parts OF the district and frequently in di-
rect touch with the ore bearing strata
The soliataric action consequent upon IL,
eruption had probably much 10 do with
the ascending ore.bearing solutions. n mo-,
with the actual deposition Of the ore.
Trending southerly from the end OF ,be
quartzite. on the east side of Prosnect
Mountain, Is . belt Of Secret CANYON shsIe'
which separates the Hamburg limsstone
from the Prospect Mountain limestone
tnroughout the southern section OF the
district. The Prospec, Mountain and
Hamburg limestonss are identical in char.
aoter in all but that the latter ia more
silicious than the former. and il veathsrs
rousher and breaks with a sharper frsc.
ture. Returning to the ~'
RUBY HILL FAULT.
n nrst observed norehward, a ths sur-
'scs near the Albion mine, sakins a. Al