The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1884-01-01
Influence by fsulting said mass to q
slight extent.
EMMA HILL.

Il
slight extent.
EMMA HILL.
Passing along the wagon road fror
Alta to the Emma mine, We observ
another mass of granite, a fact which
taken together with the other masse
of granite. should demonstrate be
yond dispute. that the granite an
derlies the whole Of both districts.
The formations belong to the paleo
goic age, but for all that the speci
mems of slgse and other fossils, founl
liz the fetid lime OF tn
Oottonwoods. in reality, belong to tn
Ayoic; still the metamorphic actor
to which the rock has undepiabl,
been subjected. verifiss the conclu
sion OF paleogoic origin.
DAVENPORT HILL.
On the Davenport hillside the sec
ond upheaval has raised series O
rocke, which contain no quartzite
but sohlst and copper. schist over.
laying the same, fact which demon
strases the destruction of the missing
strata by action of the uphesval.
This part Of Davenport Hill is very
extensively traversed by several
dykes, of hard compact trap, hard
ly distinguishable from the surround
ing lime. Two of these dykes pass
within the vicinity of the Victoris
tunnel mouth. The upper dyke runs
north. passes the Imperial and
crosses the divide, by the Davenport
mine. a fault in the northern part
or end OF E mersld hill, forms syn.
clinal curve, in the ridge to within q
short distance OF the Wellington
mine little Cottonwood), passing
thence over to and through American
Fork mining district. Another fault
on the southern flank OF Patsey Mar
ley corresponds with the northern
fault which caused the absence OF
schist. The missing rock is visible to
within short distance of the break
itself. fact which verifes the FORE
going conclusions.
1t is undeniably beyond dispute,
that the varying character of the Cote
touwood ores was caused through
and by the Influence of the different
country rocks. Emma Hill shows
carbonates o! lead and galeua in do.
lomite; and between dolomite and
cslcite, soft oxides with galena in
tbs fetid lime.
In the granite We observe sulphate
OF silver, galena and iron pyrites. OK.
ides and carbonate of copper. OF
course there are exceptions.
In the upper bed on Emma Hill
the ore deposits appear as parallel
ore chimneys on the east and west
line. In the lower or Emma ore belt,
the deposits appear az segregations
or pseudo-morphic displacements on
an extensive scale. Nature in her
curious and mysterious work has
caused here the different assures 30 to
run and join each other as to form to
ali appearance, wsll defined strata
vein which in reality it is not.
By close observation, it will be seen
that the ore does not occupy q real
vein fssure, but that the mineral
solutions circulating and ascending
from below. have entered into all and
svery open space of the extensively
assured rock, rooted in the same, dis
solved the carbonates of lime and
and deposited in its place
he mineral wealth as We find the
Iame at present.
An illustration of this action is OBJ
ervsble in the Flagstaff, South Star
md Emma mines. Here the wall rock
8 decomposed in the line of fracture, |
apparently washed out by water, and |
oagh projecting boulders show the |
.ction of mineral reagents upon the !
aEe. So every small seam OF vein |
natter should be followed up, as the
anne must lead invariably to larger
eposits of ore and indeed to bon
MAS.
An examination OF the ore beds
bows that they were formed subse-
uently to the great upheaval by as
ension from below. Descending,
10 observe the action of the igneous
ocAa more frequent. trap dykes trav-
rising the lower beds; in association
18th these dykes are observable large
eposits of ferruginous ores. Some
these dykes seem to be of gran
ic origin, changing gradually to a
character and then dis ,
ppear. after having run short dis
Ince more in the lime and quartzite. !
II the ore deposits are OF a more ]
'cent origin than the dykes. but all :
re more or less in connection with !
le same. Sometimes thu porphyry ;
Is been removed by pseudo-morphic q
,tion and has been replaced with +
e, giving the appearance ss If the 4
rmstion of the ore deposits were a
10 secondary effect of the igneous r
uptions. The strike OF these ore Z,
'posits in most cases is in conform.
7 with the general course OF the a
kes.
The Emma, Davenport and other
lls are connected with such dykes, u
ID it is very suggestive to suppose q
e dyke instrumental in the forma- q
IN OF the ore deposits. the more so 81
thnso donao.fa CONTAIN ~ ~ ~ a -