Stream Deposition

Bars

A ridge of sediment deposited in the middle or along the banks of a stream - Usually sand and gravel - Generally formed at the end of a flooding event, when flood waters recede and slow down, depositing sediment - Bar deposits can sometimes contain placer deposits- concentrations of heavy particles, such as gold, platinum, other metals or gemstones

Alluvial Fan

A stream coming into a desert form. No waves or tides. Usually snow melt going down mountains to the desert. Dumped right at the bottom of the mountain. Water soaks almost immediately because of flat dry land.

Stream Deposition

As velocity falls, largest particles settle out Results in sorting of sediment in river deposits, called alluvium Most transport takes place during floods and deposition as flood waters fall

Point Bar

Caused by erosion (outside) and deposition (inside). This eroding of land causes meandering streams

Braided Streams

Heavily loaded with sediment Sediment collects as bar deposits which separate the stream into several different channels

Oxbow Lake

Horseshoe shape that is completely cut off from the channel because of silt buildup

Meander cutoff

Land gets narrower and narrower until the erosion completely cuts through the land forming a circle

Distributaries

Main channel broken apart into smaller channels. Lots of sediment deposits

Meandering Streams

Older, well defined streams that tend to develop curves Faster on the outside (picks up material) Slower on the inside (deposited material) A "mature" river

Deltas

Sediment that accumulates at the mouth of a stream

Flood Plains

Sediments are deposited as a river floods its banks and the water velocity slows. - Most sediment is dropped closest to the river channel, with progressively less sediment carried away from the channel Organic rich material. Good for agriculture Years and years of buildup

Different Delta shapes

Stream-dominated deltas: long finger like sand bodies (Mississippi) Wave-dominated delta: seaward margin of consists of islands reworked by waves. Fan shaped. Sediments pushed out by tributaries but pushed back in by waves (creates islands) Tide-dominated deltas: continuously modified into tidal sand bodies that *parallel the direction of tidal flow* splotchy

Natural Levees

Type of Flood Plain Water goes up and over boundary, starts slowing immediately, deposits sediments, builds up from channel.