Eureka weekly sentinel. [volume] (Eureka, Nev.) 1887-1902, 1897-06-12
TINE FORMATIONS WHICH ARE oaf-stAR'
ING AND THOSE WHICH SEPARATE
THEM.

Auu0G6a rum ~
u. g.. Geological Survey Of she
Forsfeth Parallel and the Personal
Research OF the Author.
Written for as "SentiasI" BY N. II. JOsqAl
Mineral Hill, which occupies the north
ern slope Of Prospect Mountain. is com
posed Of dolomitic limestone and granite.
. The Prospect Mountain qusrtzite. which
there dipping 10 the northeast, forms the
footwall of the Ruby Hill lode. o~verlies
the granite and bends around Prospect
| Mountain to the east and west in the form
OF a horseshoe, trending on the east side
TO a point northeast OF and near the Eu-
reks Tunnel and on the west side TO an
other point extended westward from the
| Gran. mine. There il sinks beneath the
surface debris, but again appears above
the mountain qu%arternary just southwest
Of aud 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 flank
OF Prospect Mountain the quartzise dips
TO the east. The granite, which owes its
exposure on the northerly 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 were
presumably one and the same and formed
. continuous body. The face OF the
qusrtzite dips under the limestone Of the
Ruby Hill lode at an average angle OF
about 40 degrees TO the northeast. Tit
exposure Of this body Of limestone on the
surface extends over 1900 linear feet from
near the Albion shaft on the northwest,
where il 10 covered by the debris Of Spring
Valley 10 . point southeast OF and beyond
the Jackson mine, where ii comes to q mar
row point or wedge between the Prospect
Mountain quArtzite and Pogonip lime
stone. On the northern end of Ruby Hill
the limestone is cut off by g fault assure'
called the "Ruby Hill fault" The width
Of the limestone zone Of Ruby Hill. OF ths
surface, Ia from 800 TO 1000 feet; over
lying il on the north are the Secret Can
yon shale and the Hamburg limestone Of
Adams Hill. overlyipg the quarszise'
upon the east side Of Prospect Mountain
Ia 3 belt Of Hamburg limestone. which Ii
doubtless connected at some depth beneath
the surface with that OF Adams Hill. In
tervsning those two bodies 81 the surface
over q space Of about 5000 feet. 10 thu
Pogonip limestone, which runs In o CON
tinuous belt through the eastern portion
Of the district, from Diamond Valley
north Of the Bullwhacker mine to Newark
Valley on the south. 0verlying the Ham
burg limestone Of Prospect Mountain 10
band OF argilaceous shAle identical In char
acter with that which o~verliss the north
srn part Of the Ruby Hill lode. but known
Is the Hamburg shals. Nearly all Of
THE R BODIES
OF considerable magnitude and economit
value that we're discovered In Eureka Dis
trict up 10 the present time were In thu
Prospect Mountain and Hamburg lime
stone formations, Of the Csmbrian Age
but valuable deposits Of ore have beer
found in the Bullwhscker and Williams
burg mines. which are in the PogoniI
limestone and quartz porphyry Of the 81
lurisn 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 Lon'
Mountain limestone is separated from th'
Pogonip limestone by the hard qusrtzit'
reef of MeCoy's Ridge. This quartzis'
extends northwsrd to Cariboo Hill AND
southwark TO Newark Valley.
The shalss and quartzites are substan
TALLY non-ore-bearing. In some place.
the Prospect Mountain quartzise in RubJ
Hill has been impreenated with the ore
bearing solutions, but II has nowhere beer
found Of any economic value. Rhyolite
. species Of the porphyry class OF rocks
igneous and non-ore.b bearing, Ia found In
dykes Of various dimensions In several
parts OF the district and frequently in di-
rect touch with the ore bearing strata
The solfataric action consequent upon III
eruption had probably much to do will
the ascending ore-bearing solutions, IL moi
with the actual deposition Of the ore.
Trending southsrly from the end Of ths
quArtzite. on the east side Of Prospect
Mountain, Ia . belt Of Secret Canyon shalsl
! which separates shs HAmbufs limsstons