Named as second from base of seven formations of Snake River Group (uppermost part of Snake River includes unnamed Recent lava flows). Type locality is Sugar Bowl, for which unit is named, a hill 4 mi northeast of Glenns Ferry, Elmore Co, ID, Snake River basin. Preserved as gravel-capped knobs and benches which are remnants of a graded terrace occurring parallel to present stream gradient but 400 ft higher. Principal remnants lie about 8 mi east of Glenns Ferry, northeast of Snake River; 9 mi southeast of Glenns Ferry; and Indian Cove, 15 mi west of Glenns Ferry. Gravel consists mostly of quartzite, porphyry, granite and conglomerate derived from Paleozoic and granitic rocks in mountains north of Snake River Plain. Minor amount of gravel consists of rocks from Idavada Volcanics (new) and pieces of basalt, chert and argillite. Thickness at type is 20 ft. Younger than Madson Basalt of Snake River; older than Thousand Springs Basalt (revised). Stratigraphic chart. Probably deposited during runoff caused by seasonal melting of glaciers in mountains north of Snake River Plain. Late Pleistocene age suggested by freshness of gravel.

Source: GNU records (USGS DDS-6; Denver GNULEX).