Alluvium

What the map says

Gravel, sand, and silt along courses of major and intermittent streams, and in alluvial fans along valley margins. Includes small bodies of till. Also includes unstratified deposits of fine sand or silt southeast of Shadow Mountain Dam believed to be of eolian origin (Meierding, 1977, pages 41). Deposits of considerable thickness occur in major river valleys upstream from terminal moraines of Pinedale age: 15- 25 m in Horseshoe Park and Moraine Park determined by drilling (Welder, 1971); 15-122 m in Kawuneeche Valley and 53 m in Big Meadows determined by seismic study (R.A. McCullough, oral commun., 1974). These thick deposits may contain lake sediments deposited behind dams formed by terminal moraines. Lake sediments composed of gray-blue clay interlayered with peat are exposed in stream cuts in Big Meadows (Meierding, 1977, pages 42). Several bodies of alluvium were deposited at margins of lateral moraines (as in Hidden Valley) when streams were dammed by the moraines. These deposits may contain lake sediments and alluvium of Pinedale and Bull Lake age. GRI Source Map ID 141 (I-1973). Lithology: unconsolidated.

1:100,000 sheet: National Park Service Geologic Resources Evaluation program, 2006, National Park Service (2 crags). A contact line at that scale is about 100 m wide on the ground.

Gravel, sand, and silt in stream valleys and alluvial fans. Lithology: unconsolidated; alluvium; mixed.

1:100,000 sheet: Day and others, 1999, U.S. Geological Survey Open-File Report 99-0427 (3 crags). A contact line at that scale is about 100 m wide on the ground.

Served by Macrostrat (CC BY 4.0). The wording is the map's own, quoted as a fact about the mapped unit, not about any one wall.