Fourth Beach

Occurrence, Inactive

Commodities and mineralogy

Main commodities Au
Ore minerals gold
Gangue minerals garnet

Geographic location

Quadrangle map, 1:250,000-scale NM
Quadrangle map, 1:63,360-scale C-1
Latitude 64.5508
Longitude -165.3857
Nearby scientific data Find additional scientific data near this location
Location and accuracy Fourth Beach is the highest elevation auriferous strandline now known on the Nome coastal plain (Hopkins and others, 1960; Nelson and Hopkins, 1972; Tagg and Greene, 1973; Cobb, 1973 [B 1374, figure 29, p. 87]). The elevation of the Fourth Beach strandline is 125 feet. It is preserved at the base of Anvil Mountain, where it is buried by colluvium. The map location is about on Cooper Gulch at a surface elevation of 250 feet. It is in the west-central part of section 12, T. 11 S., R. 34 W., Kateel River Meridian. The location is accurate within about 500 feet.

Geologic setting

Geologic description

Fourth Beach represents the farthest advance of the sea in Quaternary time, and it has been recognized only at the base of Anvil Mountain. It formed as a true strandline beach by waves impinging upon bedrock. Unlike Third Beach, which terminates landward on a prominent scarp marked by long-continued erosion at that sea level, Fourth Beach is an inconspicuous strandline that evidently formed during a relatively short seastand. It is not generally rich enough to mine. Probably some of the gold that was concentrated at Fourth Beach sea level was eroded seaward before the beach was buried by mass-wasting deposits. Hopkins and others (1960, p. 47-48) noted that the sediments of Fourth Beach are overlain by drift of the Nome River glaciation and that the seaward edge of the deposits is truncated at the Third Beach escarpment. They postulated that Fourth Beach may have formed during some part of Submarine Beach time or during an otherwise unidentified interglacial interval. Nelson and Hopkins (1972) diagrammatically show Fourth Beach at the base of Anvil Mountain (also see Cobb, 1973 [B 1374, figure 29]).
Geologic map unit (-165.388300981609, 64.5500344152968)
Mineral deposit model Placer Au; buried, strandline beach deposit (Cox and Singer, 1986; model 39a).
Mineral deposit model number 39a
Age of mineralization Pleistocene.

Production and reserves

Workings or exploration There is no substantial production from Fourth Beach. Gold originally concentrated on this beach could have been eroded and reconcentrated in alluvial deposits below the beach.
Indication of production None

Additional comments

Considered too low grade to be of economic interest.

References

MRDS Number A012963

References

Reporters C.C. Hawley and Travis L. Hudson
Last report date 7/10/2000