Sedimentary deposits such as alluvial terrace deposits (regional flood deposits), debris flows (landslide during flood along river or stream valley), or mud flows (saturated fine-grained soils in a landslide during a flood along a river or stream valley) can produce layers several feet thick in a single event. At Mount Rainer for example in 2006 the Tahoma Creek was subjected to severe flooding, in some places flooding the river valley 400 feet across. Flood flow aggredation deposited 4 feet of granular soil in a single event near the bridge at the photograph below. The level the man is standing at was 4 feet higher than before the flood.
A park geo-scientist reported in a video presentation of the event up to 6 feet of deposition in some areas, and an accumulated 38 feet total aggredation in some areas since 1910. That is a 38-ft thick channelized or wide valley sedimentary deposit stratum or bedded strata in less than 100 years. Although the Tahoma Creek drainage valley is the downstream drainage feature of the local glacier, granular flood deposts can be produced along any river or stream valley where source rock is available upstream where rivers are present through rock geology. "Aggredation" is a term used to describe the accumulation of sediment.
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