Dexter Creek

Mine, Inactive

Commodities and mineralogy

Main commodities Ag; Au
Other commodities Sn
Ore minerals cassiterite; gold

Geographic location

Quadrangle map, 1:250,000-scale NM
Latitude 64.5817
Longitude -165.292
Nearby scientific data Find additional scientific data near this location
Location and accuracy This alluvial placer gold mine is on Dexter Creek, a west tributary to Nome River. Placer mining took place over at least 7,500 feet of Dexter Creek between elevations of 50 and 250 feet. The map location is in the NW1/4 section 33, T. 10 S., R. 33 W., Kateel River Meridian. It is locality 118 of Cobb (1972 [MF 463], 1978 [OFR 78-93]).

Geologic setting

Geologic description

Placer gold mining was underway on Dexter Creek by 1899. About 14,500 ounces of gold were produced in 1900 (Schrader and Brooks, 1900; Brooks and others, 1901). Most of Dexter Creek has been worked from its mouth to its headwater tributaries (Collier and others, 1908). Bench deposits at elevations 75 feet above the creek were worked at a few locations on the north side of the creek valley. One such is 1 mile above the mouth and 100 yards above the mouth of Grouse Gulch. Near the mouth of Dexter Creek, pay was on a blue clay false bedrock 5 feet below the surface. Upstream, 3 to 10 feet of stream gravels are on schist and marble bedrock, and pay continued downward into decomposed or fractured bedrock. Solution-enlarged fractures in marble were locally very rich and extended as much as 30 feet below the base of the gravels; karst features in bedrock probably contributed to water loss that commonly hindered mining operations on Dexter Creek (Moffit, 1913). The bench gravels were as much as 30 feet thick. The bench deposit 100 yards above the mouth of Grouse Gulch contained 5 feet of yellow clay over 15 feet of poorly sorted schist, marble, granite, and sandy clay gravels. The low elevations of the creek, from less than 50 feet to 250 feet, and proximity to the lower Nome River valley and coastal plain suggest that Quaternary sea-level fluctuations could have influenced development of some of the lower Dexter Creek placers, although most of the gold ultimately came from high-bench placer deposits. The upper south tributary to Dexter Creek is Wet Gulch, which taps the high-bench gravel between North Newton Peak and Anvil Mountain (NM248). Other headward tributaries include Grouse Gulch and Deer Gulch, which tap the Dexter high-bench (NM246), and Grass Gulch (NM266), which taps the Summit high-bench (NM247).
Bedrock in Dexter Creek is marble and schist, probably of early Paleozoic protolith age (Hummel, 1962 [MF 247]; Till and Dumoulin, 1994). Bundtzen and others (1994) classified bedrock on the uplands above Dexter Creek as porphyroclastic micaceous graphitic schist.
The completion of the Miocene Ditch to Dexter in 1903 allowed parts of the creek to be worked hydraulically, although drift mines were in operation as late as the winter of 1912-13 (Chapin, 1914). A dredge was installed in about 1918 and operated at least until 1926 (Cathcart, 1920; Smith, 1932).
Cassiterite was reported from one locality (Cobb, 1973 [B 1374]). Gold on Dexter Creek ranged in size from dust to large nuggets; gold was approximately 900 fine (Purington, 1905).
Geologic map unit (-165.29460776043, 64.5809375742348)
Mineral deposit model Alluvial placer Au (Cox and Singer, 1986; model 39a).
Mineral deposit model number 39a
Age of mineralization Quaternary.

Production and reserves

Workings or exploration Dexter Creek has been extensively placer mined from its mouth to its headwater tributaries. All types of surface placer mining operations have taken place, from hand operations to dredging. Dredging was the principal mining operation from 1918 to 1926 (Cobb, 1978 [OFR 78-93]).
Indication of production Yes; medium

References

MRDS Number A012934; A012935

References

Brooks, A.H., Richardson, G.B., Collier, A.J., and W.C. Mendenhall, 1901, A reconnaissance in the Cape Nome and adjacent gold fields of Seward Peninsula, Alaska, in 1900: U.S. Geological Survey Special Publication, p. 1-185, maps.
Till, A.B., and Dumoulin, J.A, 1994, Geology of Seward Peninsula and St. Lawrence Island, in Plafker, G., and Berg, H.C., eds., The Geology of Alaska: Geological Society of America, DNAG, The Geology of North America, v. G-1, p. 141-152.
Reporters C.C. Hawley and Travis L. Hudson
Last report date 7/10/2000