GOLD PLACERS OF THE RUBY CREEK DISTRICT
INTRODUCTION.
Late in the summer of 1907 a report was circulated that prospects
of placer gold had been discovered on Ruby Creek, a small stream
about 3 miles long that flows into Yukon River on its south side,
opposite the mouth of the Melozitna. (See map, PI. IX.) The discovery
was made at the mouth of the creek, in some fine gravel at the
level of the spring high-water mark of the Yukon. As this locality is
very accessible, especially from the settlements of Tanana, Rampart,
and Fairbanks, a good many men went to Ruby Creek during the
latter part of 1907, and extensive tracts of land on a number of the
streams were located as placer-mining ground. About 30 men
remained in the vicinity of Ruby Creek during the winter of 1907-8,
prospecting on the various creeks in this district. A number of shafts
were sunk during the winter, largely with the aid of three small steam
boilers, but the results of these operations do not appear to have been
very encouraging, for by July, 1908, most of the men had left the district,
and Discovery claim, on Ruby Creek, was the only property
that was being actively worked. The writer spent seven days in this
locality in July, 1908, and made a hasty examination of the general
geology.
GEOGRAPHIC SKETCH.
LOCATION.
The locality known as the Ruby Creek district-from the name of
the small stream on which gold was first discovered in the area-is
situated along the south bank of Yukon River, directly south of and
opposite the mouth of Melozitna River, about 175 miles below the
town of Tanana or 110 miles above Nulato, the two nearest large
settlements on the
The district is within the St. Michael recording precinct, as it is now
defined by the court for the second judicial division of Alaska. The
nearest points where supplies may be obtained are at the village of
Kokrines, 24 miles up the Yukon, and at Lewis's store, 23 miles
229
230 MINERAL RESOURCES OF ALASKA, 1908.
down the Yukon. The United States military telegraph station
called Melozi is on the north bank of the Yukon 8 miles below Ruby
Creek. The region is easily reached throughout the year by way of
Yukon River.
RELIEF.
For a distance of 10 miles along the south bank of the Yukon the
Ruby Creek area presents rolling hills from 400 to 500 feet high that
overlook the river with rock bluffs 200 to 300 feet high. These hills
may be considered to form the northeast end of the Kaiyuh Mountains,
which extend for about 175 miles toward the southwest to
lower Innoko River. The Ruby Creek hill country is noteworthy as
being the only place along the south side of Yukon River between
Tanana River and Bering Sea, a distance of over 800 miles, where the
highland is made up of the older rocks, and bluffs of consolidated
Bedrock form the immediate bank of the Yukon. The south bank
of the Yukon throughout all the rest of this distance is made up of low
bluffs of unconsolidated, alluvial silt, which covers the older hard-rock
formations for distances of 5 to 20 miles or more back from the stream.
The rolling hills near the Yukon gradually rise to low, dome-shaped
mountains 1,200 to 1,500 feet in height 10 miles south of the stream,
and these low mountains continue southward and southwestward to
the Innoko Valley.
DRAINAGE.
The drainage of this area is of the kind that may be expected to
characterize a low, rolling region. None of the streams carry much
water and their grades are not steep. Nowitna River discharges into
the Yukon from the south about 36 miles above Ruby Creek, after
meandering across extensive flats that extend southward from the
Yukon for 20 miles or more. Along the wide valleys of the larger tributaries
of the Nowitna broad strips of flat bottom land extend far back
into the hills, and the Ruby Creek hills descend eastward to these fiat
lands of the lower part of the Nowitna Valley. A large western
tributary of the Nowitna called the Solatna rises southeast of the
northeast end of the Kaiyuh Range, which is formed % the low domed
mountains southwest of the Ruby Hills. The largest streams
whose sources are in the Ruby Creek district flow toward the east into
the Nowitna Flats. These streams, named in order from north to
south, are Big, Independence, and Eureka creeks and the headwater
tributaries of the Solatna-Wolf, Joe, New York, Beaver, and Dome
creeks. There are also several large creeks that rise in the Ruby
Hills and drain toward the west, across the wide flats that are occupied
by boug &, small lakes, and the meandering lower course of
Yuko River, which discharges into the Yukon about 23 miles below
Ruby Creek. Only two of these streams have been named-Ora and
GOLD PLBCERS OF RUBY CREEK DISTRICT. 231
Main creeks; both empty into a slough that leaves the Yukon just
below the bluffs along the main river.
Big and Ora creeks run east and west, respectively, 3 or 4 miles
south of the Yukon and somewhat parallel to it. The divide that
separates these creeks from the Yukon is the southern boundary of
the strip of hilly country, from 2 to 3 miles wide and about 10 miles
long, that extends along the south bank of the Yukon with the
bluffs already mentioned overlooking the river. The bluffs are
separated by small valleys, at right angles to the Yukon, that are
occupied by creeks from 1 to 3 miles in length. Named from east to
west these streams, which drain directly into Yukon River, are as
follows: Flat, Center, Melozi, Ruby, Short, and Hannah creeks.
They are all small streams with a very scanty supply of water. Thus,
the Ruby Creek hills and the low dome-shaped mountains that rise to
the southwest of them form a divide between waters that flow eastward
into the Nowitna and westward to the Yuko Flats, and thence
into Yukon River.
VEGETATION.
The vegetation of the Ruby Creek district is that typical of this
part of the Yukon Valley. The white spruce is the only tree of
importance, and it grows to a good size only on the flats, being
small and scrubby on the hills.
GEOLOGIC SKETCH.
The bed rock of the hills and low mountains of the Ruby Creek
district comprises a variety of old altered sedimentary rockscrystalline
limestones, garnet-mica schists, and mica-quartz schists
with so fine a grain that they may well be called coarse slates. These
rocks occur in the bluffs along the Yukon. The bluff exposures
show local zones of shearing, with quartz stringers deposited along
the fractures. Near Flat Creek the results of shearing in the schists
are somewhat pronounced and large quartz lenses and stringers
occupy the openings thus produced. On the surface these quartz
deposits are of the lens or bunch type, with no particularly uniform
trend or thickness for any considerable distance. Two principal
exposures of quartz were seen, one about 100 yards below the mouth
of Flat Creek that shows a maximum thickness of 4 or 5 feet on its
face, and another about 100 feet downstream that is several feet
in thickness but of no marked linear extent. Assays of samples of
quartz from these exposures are said to have shown good values
in gold. In 1906 a tunnel, now caved in, was run in on the largest
of these quartz deposits, it is said for a distance of 150 feet, with the
object of following the quartz that shows on the surface of the bluff.
After the work had progressed for a few feet it was found impracticable
to follow the irregularities of the quartz stringers with a straight
232 MINERAL RESOURCES OF ALASKA, 1908.
tunnel, and most of the tunnel was run through the slaty schist
country rock, as is shown by the material on the dumps. In brief,
the bodies of quartz were found to be too irregular and uncertain in
extent to be mined by tunnels, and what has been demonstrated at
this place will probably be found to be true of any other quartz
deposits in this region.
Farther inland, quartzite schists, mica-quartz schists, cherty
limestone, and cherts make up the low mountains. All these rocks
have been considerably changed from their original form by metamorphism,
but not to a degree that noticeably obliterates their
sedimentary origin and arrangement. They are similar to and are
presumably to be correlated with formations that occupy large areas
of the mineral belt between Yukon and Tanana rivers, 200 miles to
the east.
The rocks of the district have been intruded to some extent by
dikes of igneous rock. These dikes are of diabasic and granitic
types.
The alluvial deposits that fill the bottoms of the valleys are moderate
in amount and thickness, and appear to be the gradual accumulations
produced by a meager drainage such as now prevails. The
rounded forms of the hills and mountains suggest that the present
aspect of the country is the result of a long period of uniform erosion.
GOLD.
Colors of placer gold are reported to have been found in the alluvial
deposits of nearly all the streams that rise in the Ruby Creek district,
but no rich gold-bearing gravels have yet been found.
In the fall of 1907 a number of men, following the usual practice
adopted when a .new placer district first attracts attention, located
practically all of the alluvial bottom lands along the streams of
this district -as placer-mining ground. These locations comprised
both association placer groups containing 160 acres and single 20-
acre tracts. Large areas of the valley slopes were also located as
so-called l 'bench claims."
During the winter of 1907-8 about 30 men prospected for placer
gold in the alluvial deposits of the creeks by sinking a number of
holes to bed rock. Most of this work was done on Ruby and Big
creeks, but a few holes were sunk on Boston Creek and two of its headwater
tributaries, Logger .and Boston gulches. Some prospecting was
also done on the headwaters of the Solatna-Beaver and Dome creeks.
One hole that did not reach bed rock was sunk on Melozi Gulch.
On Big Creek about 15 holes from 15 to 60 feet deap were dug
to bed rock. The deeper holes are on the upper part of the creek.
Farther downstream the unconsolidated deposits are not so thick.
Washed gravel of schist rocks lies on bed rock in a layer from 1 to 7
feet thick and is overlain by sandy clay and muck. Bowlders of
igneous rocks and quartz up to 1 foot in diameter are also present.
It is reported that colors of gold were found in all the holes on Big
Creek. A good deal of iron pyrite is included in the gravel, both as
washed grains and inclosed or attached to the larger fragments of
slaty bed-rock material.
The unconsolidated valley deposits on Ruby Creek probably average
about 15 feet in depth. They are composed of muck, loamy
sands, patchy layers of flat schist and slate pebbles, and a good many
water-rounded bowlders of igneous rock. The bed rock is schist,
slate, and limestone in the form of rectangular blocks and slabs.
The results that had been obtained by the close of the winter
prospecting season do not appear to have been of sufficient promise
to encourage the prosecution of summer work, except at the mouth
of Ruby Creek. In July, 1908, two men were carrying on open-cut
work on Discovery claim, the first above the Yukon. They were
working about one-eighth of a mile back from the river on the east
side of Ruby Creek, in a bank of muck, silt, gravel, and bowlders.
A small ditch had been built with an intake about 400 yards above
to bring a sluice head of water to the open cut. The bed rock in this
cut is a blocky, impure, banded crystalline limestone similar to that
exposed on the Yukon in the "lime bluff" just below the mouth of
Ruby Creek. I t is in the shape of sharp-cornered rectangular blocks
and bricklike slabs that have not been rounded by erosion. It is all
in a shattered condition, so that it has to be handled in working.
The material handled consists of this loose blocky limestone, flat
pieces of coarse mica slate similar to that seen above and below Ruby
Creek on the Yukon, close-grained cobbles of diabase, and large,
heavy bowlders of medium-grained diorite, similar to that seen in a
large dike on the Yukon. These bowlders are from 12 to 18 inches
in diameter and are well rounded. The large, heavy bowlders do
not lie on bed rock, as might be expected, but for the most part several
feet above it in the muck. The finer wash is below the muck,
on bed rock, and is made up mostly of flattish slate pebbles mixed
with loamy sand. This sand also fills the spaces between the blocky
limestone fragments of the bed rock. Mixed with the sand and in
patchy layers within it and on top of the blocky hestone are finer
waterworn gravels consisting of slate pebbles, mostly flat. These
layers of fine washed material do not appear to be continuous for any
great extent, nor are they very thick. They carry most of the placer
gold, which is in the form of fine, flaky, light particles, not as large
as bird shot. Owing to this fineness, it is hard to save all of the gold
in the sluice boxes.
Up to July, 1908, about $1,000 worth of this fine gold had been
produced from the open cut on Discovery claim on Ruby Creek.