Geoscience Reference
In-Depth Information
22.5
°
N
TROPICS
22.5
°
S
Sea ice
Sheltered sea
Storm-wave dominated
Swell-wave dominated
Tropical cyclone tracks
Fig. 8.1
Distribution of temperate coasts including wave heights and types. (After Davies 1980; Short 1999.)
Washover
Dunes
Beach
Ebb tidal
delta
Flood
tidal
delta
Marsh
Mainland
Lagoon
Barrier
Fig. 8.2
Diagram of main sedimentary
environments considered in this chapter.
Shoreface
large, shore-parallel accumulations of sediment
(of which a beach forms the most seaward part),
deposited under wave action and which separ-
ate a low-lying area (marsh, lagoon or estuary)
from the ocean. Barrier islands are barriers that
are surrounded on all sides by water. Coastal
dunes develop in the supratidal zone by aeolian
transport and deposition of sand from adjacent
beaches.
The critical conditions for development of
these environments are as follows:
1
adequate sediment supply;
2
suitable accommodation space (shaped by
antecedent coastal morphology);
3
sufficient wave energy levels to move avail-
able sediment.
Sediment is derived from various sources and
has varying texture. There is a broad latitudinal
control in that gravel beaches are preferentially
developed in glaciated or formerly glaciated
(paraglacial) regions (Ballantyne 2002). Sedi-
ment texture is an important constraint on
