Geology Reference
In-Depth Information
submergence, may open up to form marine inlets and
embayments. New lagoons may form where rising sea
levels cause the flooding of low-lying areas behind dune
fringes on coastal plains. They may also form where
depressions are flooded as rising water tables promote the
development of seasonal or permanent lakes and swamps.
Wherever there is a supply of replenishing sediment, the
deepening and enlargement of estuaries and lagoons may
be countered.
Corals and algae living on the surface of intertidal
reef platforms will be spurred into action by a rising sea
level and grow upwards (Figure 13.21e). However, reef
revival depends upon a range of ecological factors that
influence the ability of coral species to recolonize sub-
merging reef platforms. In addition, the response of corals
to rising sea levels will depend upon the rate of sea-level
rise. An accelerating rate could lead to the drowning and
death of some corals, and to the eventual submergence of
inert reef platforms. Studies suggest that reefs are likely
to keep pace with a sea-level rise of less than 1 cm/year, to
be growing upwards when sea-level rise falls within the
range by 1-2 cm/year, and to be drowned when sea-level
rise exceeds 2 cm/year (Spencer 1995).
are far-reaching and likely to impact severely on humans
living at or near coasts.
ESSAY QUESTIONS
1 How do currents and waves produce
landforms?
2 Why do deltas display such a variety
of forms?
3 Assess the likely consequences of a
rising sea level during the present
century for coastal landforms.
FURTHER READING
Bird, E. C. F. (2000)
Coastal Geomorphology: An
Introduction
. Chichester: John Wiley & Sons.
A highly readable, systematic coverage of form and
process along coasts. Excellent.
Carter, R. W. G. (1992)
Coastal Environments
. London:
Edward Arnold.
Covers applied coastal geomorphology, linking the phys-
ical and biological resources of coasts with their exploita-
tion and use. Good for students interested in coastal
management.
SUMMARY
Waves and tsunamis buffet coasts, nearshore currents
wash them, and tides wet them. Rocky coasts are dom-
inated by erosional landforms - shore platforms and
plunging cliffs, cave, and arches and stacks, and many
more. Some erosional landforms occur in predominantly
depositional environments, as in tidal creeks cutting
across salt marshes. Depositional landforms along coasts
are many and varied. Beaches are the commonest fea-
tures, but assorted species of spits and barriers are
widespread. Other depositional landforms include beach
ridges, cheniers, coastal sand dunes, estuaries, tidal flats,
salt marshes, mangals, marine deltas, and coral reefs
and atolls. Humans affect coastal erosion and deposition
by increasing or decreasing the sediment load of rivers
and by building protective structures. Many beaches in
Western Europe, the USA, and Australia need feeding
with sand to maintain them. The effects of a rising sea
level over the next century following the warming trend
King, C. A. M. (1972)
Beaches and Coasts
, 2nd edn.
London: Edward Arnold.
Dated, but is well worth digging out for the classic
examples of coastal features.
Komar, P. D. (1998)
Beach Processes and Sedimentation
,
2nd edn. Upper Saddle River, N.J.: Prentice Hall.
A top-flight technical topic on beach process, but some
mathematical knowledge is needed.
Masselink, G. and Hughes, M. G. (2003)
An Introduc-
tion to Coastal Processes and Geomorphology
. London:
Arnold.
An excellent introduction to the environments and
processes
occurring
along
the
coastlines
of
the
world.
