Formation of Outwash Plains Flashcards
What is an outwash plain?
An outwash plain, also known as a sandur, is a flat expanse of sediment in the pro-glacial area.
What happens to meltwater streams as they enter lowland areas beyond the ice front?
Meltwater streams gradually lose energy as they enter lowland areas beyond the ice front.
Where is the largest material deposited in an outwash plain?
The largest material is deposited nearest the ice front in an outwash plain.
Where is the finest material deposited in an outwash plain?
The finest material is deposited further away from the ice front in an outwash plain.
How are outwash plains typically drained?
Outwash plains are typically drained by braided streams.
What are braided streams?
Braided streams are river channels subdivided by numerous islets and channels.
What happens to debris-laden braided streams at the end of the melting period?
Debris-laden braided streams lose water at the end of the melting period and carry less material.
What happens to the channel of a braided stream when material is deposited in it?
When material is deposited in the channel of a braided stream, it causes the channel to divide.
What is the initial stage of braiding in a stream?
The initial stage of braiding in a stream is the formation of a mid-channel bar which grows downstream.
What happens to the size of a mid-channel bar as discharge decreases?
As discharge decreases, the size of the mid-channel bar increases because finer material is added to it.
How are channel bars stabilized and become more permanent features?
Channel bars are stabilized by vegetation and become more permanent features.
What happens to unvegetated bars in braided streams?
Unvegetated bars lack stability and often move, form, and reform with successive flood or high-discharge events.
Where is an extensive sandur located on the south coast of Iceland?
An extensive sandur is located on the south coast of Iceland.
What feeds the sandur on the south coast of Iceland?
The sandur on the south coast of Iceland is fed by numerous meltwater streams from glaciers such as Gigjökull and Solheimajökull.
What is the distance from the edge of the upland area to the present position of the sea in Iceland’s sandur?
The distance from the edge of the upland area to the present position of the sea in Iceland’s sandur is approximately 5 km.
