Deltas Flashcards
What is a delta?
Large areas of sediment deposited at the mouth of a river -> form when deposition is greater than waves and tides removing it
Where are deltas formed?
Where the river meets the sea in a network of distributaries
What is a distributary?
A stream that branches off and flows away from a main stream
What is a levee?
Layers of material packed together
How is a levee formed?
High rainfall creates more water in a river, this then bursts and sediment is deposited
What is a crevasse splay?
A sedimentary deposit
How is a crevasse splay formed?
Levee breaks under pressure, water travels through gaps
Sediment for river deposited to side of river
What are the different types of delta?
Cuspate
Arcuate
Bird’s Foot
Cuspate delta
Pointed extension to the coastline, sediment is built up and shaped by slow currents in opposite directions
Few distributaries
Arcuate delta
Delta grows seaward and wave action smooths its edge
Lots of distributaries
Bird’s foot delta
Distributaries built outwards in branching pattern (deposition exceeds erosion)
Mississippi River source and size of whole drainage basin
Lake Nataska
3 million km^2
How was the Mississippi delta formed?
Sediment from upper course deposited around distributaries near mouth
River then takes new path
Lobe keeps changing to get most efficient way of movement possible
What is a delta cycle?
Lasts every 1000/2000 years
Results in new delta lobe
What is the present day lobe in the Mississippi Delta?
Balize Delta
