|Quadrangle map, 1:250,000-scale||SR|
|Quadrangle map, 1:63,360-scale||D-7|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This site represents a gold placer mine at and near the confluence of Gulch and lower East Fork Sixmile Creeks. The creeks are located in T. 8 N., R. 1 W., of the Seward Meridian. The map site is just northeast of the Seward Highway, about 1.25 miles southeast of the Hope road turnoff. This is location 142 of Cobb and Richter (1972), location 166 of MacKevett and Holloway (1977), location 14-15 of Cobb and Tysdal (1980), and location P-73 of Jansons and others (1984). This location is accurate to within 300 feet.|
Gulch Creek and lower East Fork Sixmile Creek occupy narrow bedrock canyons along most of their length and contain thin, discontinuous gravel deposits. The bedrock in these drainages is slate and sandstone of the Valdez Group of Late Cretaceous age (Nelson and others, 1985).
Gravels in a low bench, mined at the mouth of Gulch Creek, are composed of pebbles and boulders of slate, sandstone, and granite and have a clay matrix (Tysdal, 1978 [MF-880B]). Mining about 1.5 miles upstream worked old channel gravels consisting of horizontally stratified gravel having a locally compact clay and sand matrix (Tysdal, 1978 MF-880-B]).Gravels in the active steam bed range from loose and sandy on the surface, to clay cemented, with bouldery gravel near bedrock. Some of the boulders are 5 feet or more feet in diameter. Fine gold is disseminated throughout the gravels, but the pay streak is on bedrock and in fractures and is accompanied by sticky, tan clay (Jansons and others, 1984). The gold is flat, smooth, and medium coarse to coarse (Johnson, 1912). Nuggets as heavy as 5 ounces have been recovered from Gulch Creek (Jansons and others, 1984).
|Geologic map unit||(-149.402061146902, 60.7757377557701)|
|Mineral deposit model||Placer Au (alluvial) (Cox and Singer, 1986; model 39a).|
|Mineral deposit model number||39a|
|Age of mineralization||Quaternary.|
|Workings or exploration||
Prior to 1906, the placer was worked mainly by pick and shovel. Hydraulic mining predominated from 1906 through 1917. Most of the gold was taken from the mouth of Gulch Creek and from East Fork SixmileCreek just below its confluence with Gulch Creek. East Fork Sixmile Creek has been worked mainly between Gulch Creek and Sixmile Creek (Moffit, 1906).
In 1911, two hydraulic plants were in operation. The lower, smaller plant operated at the junction of Gulch and East Fork all season using an 8-inch pipe with a 2.5-inch nozzle. A 4,000-foot-long, 2-foot-wide ditch provided water. The gravel was piped into two lead boxes and then into a string of nine, 12-foot-long, 1-foot-wide sluice boxes set with pole riffles (Johnson, 1912). The upper plant, situated a short distance above the mouth of Gulch Creek, was not in operation when Johnson visited in 1912. There, the gold-saving apparatus consisted of a string of 11 sluice boxes with a 3-foot-square cross section laid on bedrock (Martin and others, 1915). In 1917, two men were hydraulic mining at the mouth of Gulch Creek (Johnson, 1919 [B 692-C, p. 175-176]).
In the early 1980s, the U.S. Bureau of Mines collected suction dredge samples at the head of Gulch Creek. They yielded 0.0006 to 0.0034 ounce of gold per hour. Two other samples from upper Gulch Creek contained 0.0008 to 0.0296 ounce of gold per cubic yard. Nine placer samples consisting of surface alluvium collected from the canyon of lower East Fork Sixmile Creek, contained 0.0019 to 0.015 ounce of gold per cubic yard (Jansons and others, 1984).Since the early 1980s small-scale suction dredging has become a popular mining method and occurs intermittently up to the present time (C. S. Huber, oral communication, 2000).
|Indication of production||Yes; small|
|Reserve estimates||The quantity of the gravel both on the benches and in the active stream channel is limited. No estimate of reserves is available.|
|Production notes||The total estimated production is 1,000 to 2,500 ounces of gold, of which as much as 250 ounces has been produced since 1975 (Jansons and others, 1984).|
Brooks, A.H., 1915, Mineral resources of Alaska; report on progress of investigations in 1914: U.S. Geological Survey Bulletin 622, 380 p.
Brooks, A.H., 1916, Mineral resources of Alaska, report on progress of investigations in 1915: U.S. Geological Survey Bulletin 642, 279 p.
Cobb, E.H., and Richter, D.H., 1972, Metallic mineral resources map of the Seward quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-466, 2 sheets, scale 1:250,000.
Cobb, E.H., and Tysdal, R.G., 1980, Summaries of data on and list of references to metallic and selected nonmetallic mineral deposits in the Blying Sound and Seward quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-621, 276 p.
Hoekzema, R.P., and Sherman, G.E., 1983, Mineral investigations in the Chugach National Forest, Alaska (Peninsula study area): U.S. Bureau of Mines in-house report; held at U.S. Bureau of Land Management Alaska State Office, Anchorage, 524 p.
Jansons, Uldis, Hoekzema, R.B., Kurtak, J.M., and Fechner, S.A., 1984, Mineral occurrences in the Chugach National Forest, southcentral Alaska: U.S. Bureau of Mines Mineral Land Assessment 5-84, 218 p., 2 sheets, scale 1:250,000.
Johnson, B.L., 1912, Mineral resources of Alaska, report on progress of investigations in 1911--Gold deposits of the Seward-Sunrise region, Kenai Peninsula: U.S. Geological Survey Bulletin 520-E, p. 131-173.
MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous and selected non-metalliferous mineral deposits in the eastern part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-A, 99 p., 1 sheet, scale 1:1,000,000.
Martin, G.C., Johnson, B.L., and Grant, U.S., 1915, Geology and mineral resources of Kenai Peninsula, Alaska: U.S. Geological Survey Bulletin 587, 243 p.
Moffit, F.H., 1906, Gold fields of the Turnagain Arm region: U.S. Geological Survey Bulletin 277, p. 7-52.
Nelson, S.W., Dumoulin, J. A., and Miller, M.L., 1985, Geologic map of the Chugach National Forest, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1645-B, 16 p., 1 sheet, scale 1:250,000.
Paige, Sidney, and Knopf, Adolph, 1907, Geologic reconnaissance in the Matanuska and Talkeetna basins, Alaska: U.S. Geological Survey Bulletin 327, 71 p.
|Reporters||Jeff A. Huber (Anchorage)|
|Last report date||5/13/2000|