Types of Deltas
(A)(A)
Fan or triangle shape
-E.g.
Nile Delta in Egypt
-Formed
when a river deposits its load uniformly over the
whole area.
(B)
“Bird’s foot” shape
-E.g.
Mississippi Delta in USA
-Formed when a
river deposits its load rapidly at the river mouth and
extends outwards into the sea like the claws of a bird.
How are
Deltas formed?
-As
the river approaches the calmer
sea water or a large lake, its velocity
decreases.
-It
starts to deposit its load at the mouth.
-As
the sediments continue to accumulate,
they obstruct the path of the river.
-The
river then branches into smaller
rivers to find a way around the obstruction
-These
smaller rivers are called distributaries.
-The
distributaries carry water away from the main river in several
directions before finally reaching the sea.
•
-Over
time, layers of different materials such as sand,
silt and clay are built up on the sea floor and a delta
results.
-Gradually,
plants may grow on the delta and stabilize
it.
Plan
View Cross-sectional View
•
Examples of
Deltas in the World
