- Recessional glaciolacustrine deposits—Silt, clayey or sandy silt, and silty sand, typically with scattered dropstones; local lenses or beds of sand or gravel. Sediments are loose or soft, massive or laminated to thinly bedded, and locally display varve-like rhythmites. Kame lake deposits locally display some soft sediment deformational features, such as tilted or deformed bedding, and were deposited in small proglacial lakes in upland ice-marginal settings, such as the Youngs Creek ice-contact complex. Upward fining sequences record waning lake sedimentation in small proglacial lakes. Upward-coarsening sequences may begin as glacial-lake deposits (units Qglr and Qgos) and grade into overlying deltaic (unit Qgod) and fluvial (unit Qgof) deposits as a result of progradation of the outwash complexes into Glacial Lake Skykomish or smaller ice-marginal glacial lake environments. Glacial Lake Skykomish sediments were deposited mostly below ~400 to 440 ft (122–134 m) elevation in the northern part of the map area (Cross Sections A and B). Broecker and others (1956) reported a radiocarbon date of 11,900 yr BP from peat overlying soft blue clay (unit Qglr) in the Lake Joy quadrangle (Dragovich and others, 2012), indicating that the area was fully deglaciated before that time.
- African Plate (Wikipedia)
The African Plate, also known as the Nubian Plate, is a major tectonic plate that includes much of the continent of Africa (except for its easternmost part) and the adjacent oceanic crust to the west and south. It is bounded by the North American Plate and South American Plate to the west (separated by the Mid-Atlantic Ridge); the Arabian Plate and Somali Plate to the east; the Eurasian Plate, Aegean Sea Plate and Anatolian Plate to the north; and the Antarctic Plate to the south.