Lecture 28 (Wednesday, April 3, 2002): Streams, and Rivers
Brief outline of this lecture:
Streams and rivers
Main points of this lecture:
Streams emerging from mountains onto plains commonly deposit sediment in alluvial fans.
Streams and rivers form a continuum from braided to meandering morphologies.
Coarse sediment and sparse surrounding vegetation favor formation of braided streams; fine sediment and dense surrouding vegetation favor formation of meandering streams.
Meandering streams can loop back on themselves, cutting off their flow and leaving behind ox-bow lakes.
Meandering streams migrate laterally toward the outside of their meanders, leaving behind fining-upward sequences of sediment in their point bars.
Rivers can establish floodplains and then cut deeper, leaving behind high relict floodplains called terraces.
Figures used in this lecture:
A sketch and a photograph of alluvial fans
Meandering vs. braided rivers
Meander cut-off and formation of an ox-bow lake
Reading assignment: Chapter 6.
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