Running Water - The Changing Earth: Exploring Geology and Evolution - page 313

Mediterranean Sea

0 10 km

Delta Pass

Alexandria

North
Pass

Highlands

EGYPT

Delta plain

Northeast
Pass

South
Pass

Marsh and saltflat

Cairo

Barrier islands

Abandoned
distributaries

Southwest
Pass

0 500 km

Gulf of Mexico

The Mississippi River delta on the U.S. Gulf Coast is
stream dominated.

The Nile delta of Egypt is wave dominated.

a

b

The Ganges-Brahmaputra
delta of Bangledesh is tide
dominated.

c

BANGLADESH

Older surfaces

Delta plain

Tidal flat

Tidal sand bar

0 16 km

Bay of Bengal

◗ Figure 12.15 Marine Deltas

deposits that show little or no layering. Of course, the domi-
nant type of deposition can change through time, so a
particular fan might have both types of deposits.

more than a passing notice in the news. Widespread cata-
strophic fl ooding in the United States took place in 1993
(see Geo-inSight on pages 316 and 317), but since then,
several other areas in North America and elsewhere have
experienced serious flooding. As this was being written
in August 2007, another tragic flood was taking place in
Southeast Asia, particularly in India and Bangladesh. More
than 2100 people have perished and millions have been
displaced by swollen rivers, overflowing from monsoon
rains. As displaced people fl ee to high ground, so does the
wildlife, including poisonous snakes that have claimed
dozens of lives.

CAN FLOODS BE PREDICTED
AND CONTROLLED?
When a river or stream receives more water than its chan-
nel can handle, it fl oods, occupying part or all of its fl ood-
plain. Indeed, fl oods are so common that unless they cause
considerable property damage or fatalities, they rarely rate