Located on Tanana River at Bluff Cabin Ridge, 1.3 km (0.8 mi) north of Bluff Cabin, 1.6 km (1 mi) south of Goodpaster River and 9.2 km (5.7 mi) east of the community of Big Delta.
Named in 1885 by Lieutenant Allen (1887, p84), USA, for Otis Tufton Mason of the Smithsonian Institution.
Goodpaster Flats, Shaw Creek Flats,
Lakes:Big D Pond, Bluff Cabin Lake, Clearwater Lake, Little Lost Lake, Lost Lake, Quartz Lake, Thompson Lake,
Mountains:Ridges:Rivers:Delta River, Goodpaster River,
Streams:Clearwater Creek, Corda Creek, Cottonwood Creek, Eagle Creek, Flat Creek, Gilles Creek, Indian Creek, Jarvis Creek, Progressive Creek, Rapid Creek,
Cities: