REVISION AS CAMBRIDGE GEOGRAPHY: RIVERS - DELTAS.

1. AS GEOGRAPHY
HYDROLOGY
4 QUESTIONS
REVISION
DELTA

2. DEFINITION
Delta is an area of land (very young) formed by the significant build-up
of river sediment at the mouth of a river (e.g. Danube Delta below).

3. QUESTION 1
Name three different types of delta.

4. ANSWER
Arcuate, bird’s foot,
estuarine, cuspate.

5. QUESTION 2
Under what conditions are deltas formed?

6. ANSWER
When the rate of supply of
fluvial sediment is greater than
the rate at which it is removed
by marine processes.

7. QUESTION 3
What are the two main elements of a delta?

8. ANSWER
The delta front (shoreline and offshore zone) and the delta plain.

9. QUESTION 4
What features of vertical structure do deltas often display?

10. ANSWER
They often have near-horizontal layers of sediment known as bottom-
set, fore-set and top-set beds.

11. IMPORTANT
The key issue in delta formation is the balance between input and
output of sediment at the mouth.
The Mississippi delta is one of the very few largely unaffected by marine
processes and so the fingers of sediment associated with the major
distributaries are able to continue growing into the Gulf of Mexico.
The process of flocculation may be significant – as fresh and salt water
mix, clay particles become electrically charged and combine, becoming
heavy enough to fall out of suspension.