320
......
R:H" Charlier and Chr. P. De Meyer
Matthews, E.R, 1979, Seasonal variation in volume and morphology of some
western Taranaki beaches • N.Z.J. Geol. & Geoph. 4, 465-473.
6
Other Littoral Environments
This book has centered on the coastal erosion affecting beaches. It is self evident
that other littoral environments can be subject to erosive processes, resulting from
natural processes and human interference. These include lagoons, deltas,
estuaries, wetlands and coastal marshes, coral reefs, and cliffs. The consequences
of disturbing, or exploiting coral reefs have been touched upon.
Coastal cliffs exist at all latitudes, they are, at least in part, the result of sculptural
action of the sea. They retreat in a front that remains parallel to itself and leave at
their foot a gently sloping abrasion platform ; sometimes detached blocks are left
behind which play the role of temporary natural breakwaters while here and there
a highly protruding part of the former cliff maintains itself (stacks, sea-arches
and the like). Geomorphologists distinguish live (regularly battered by the
waves), stabilized (waves reach it only at times of exceptionally violent storms),
and dead cliffs (when the shoreline has moved seawards or aggradation has
separated them from the sea).
A cliff is subject to marine and subaereal attack. The sea saps a cliff at its base,
destabilizes the scarp, lowers the abrasion platform and 'ttuarries" the cliff.
Besides a mechanical effect, the ocean exerts chemical and corrosive effects,
while freezing temperatures favor the formation of notches. Haloclastisis,
hydroclastisis and biological processes contribute to the progress of erosion.
Subaereal processes act upon the scarp itself and on the cliff's summit. The
nature of the rock, as with marine erosion, plays an important role. One of the
authors has observed cliff destruction due to humidity, including frequent
precipitations, on the isle of Wight and close to the Golden Sands north of Varna
(Bulgaria).
The rate of retreat ofa cliffvaries considerably ; it is not unusual for a retreat to
occur rapidly and suddenly. The magnitude is often impressive : to cite a
frequently given example (Valentin, H., 1971, Land loss at Holderness, 18521952. In : Steers, J.A. (ed.), Applied coastal geomorphology : London,
Macmillan) over a period of one century at Holderness (Great Britain) cliffs
retreated 120 m (nearly 440 ft) along a 60 km (roughly 37 mi) front resulting in a
land loss of 720 ha (about 1800 acres) and of 100 million m 3 (130 million cu.yd)
of clay. During the Winter storms of 1953, the cliffs retreated 10 m (32.4 ft) in
two days.
......
R:H" Charlier and Chr. P. De Meyer
Matthews, E.R, 1979, Seasonal variation in volume and morphology of some
western Taranaki beaches • N.Z.J. Geol. & Geoph. 4, 465-473.
6
Other Littoral Environments
This book has centered on the coastal erosion affecting beaches. It is self evident
that other littoral environments can be subject to erosive processes, resulting from
natural processes and human interference. These include lagoons, deltas,
estuaries, wetlands and coastal marshes, coral reefs, and cliffs. The consequences
of disturbing, or exploiting coral reefs have been touched upon.
Coastal cliffs exist at all latitudes, they are, at least in part, the result of sculptural
action of the sea. They retreat in a front that remains parallel to itself and leave at
their foot a gently sloping abrasion platform ; sometimes detached blocks are left
behind which play the role of temporary natural breakwaters while here and there
a highly protruding part of the former cliff maintains itself (stacks, sea-arches
and the like). Geomorphologists distinguish live (regularly battered by the
waves), stabilized (waves reach it only at times of exceptionally violent storms),
and dead cliffs (when the shoreline has moved seawards or aggradation has
separated them from the sea).
A cliff is subject to marine and subaereal attack. The sea saps a cliff at its base,
destabilizes the scarp, lowers the abrasion platform and 'ttuarries" the cliff.
Besides a mechanical effect, the ocean exerts chemical and corrosive effects,
while freezing temperatures favor the formation of notches. Haloclastisis,
hydroclastisis and biological processes contribute to the progress of erosion.
Subaereal processes act upon the scarp itself and on the cliff's summit. The
nature of the rock, as with marine erosion, plays an important role. One of the
authors has observed cliff destruction due to humidity, including frequent
precipitations, on the isle of Wight and close to the Golden Sands north of Varna
(Bulgaria).
The rate of retreat ofa cliffvaries considerably ; it is not unusual for a retreat to
occur rapidly and suddenly. The magnitude is often impressive : to cite a
frequently given example (Valentin, H., 1971, Land loss at Holderness, 18521952. In : Steers, J.A. (ed.), Applied coastal geomorphology : London,
Macmillan) over a period of one century at Holderness (Great Britain) cliffs
retreated 120 m (nearly 440 ft) along a 60 km (roughly 37 mi) front resulting in a
land loss of 720 ha (about 1800 acres) and of 100 million m 3 (130 million cu.yd)
of clay. During the Winter storms of 1953, the cliffs retreated 10 m (32.4 ft) in
two days.