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tidal currents, coupled with the requirement for
a suitable accommodation space in which to form
(Oertel 1985).
Mainland-attached beaches are backed by
dry land rather than water. These beaches (and
some barriers) may be strongly influenced by
the onshore and nearshore topography. A
number of distinctive beach planform shapes
develop in response. These include headland-
embayment systems and cuspate forms (salients,
forelands and tombolos) (Sanderson & Elliot
1996).
Coastal dunes constitute the aeolian com-
ponent of many temperate beach systems and
exhibit a wide range of morphologies (Fig. 8.7).
In temperate regions many coastal dunes are
vegetated. The dunes begin as accumulations
around debris on the beach, typically drift lines
of seaweed and other material. Initial coloniza-
tion by strand-line vegetation partly stabilizes
these dunes and may permit continued accretion
as wind-blown sand is trapped by the vegeta-
tion. Dunes comprise varying areas of vegetated
and unvegetated sand and are intimately linked
to their source beach areas (Sherman & Bauer
1993).
On prograding systems with abundant sedi-
ment supply and strong vegetation growth,
shore-parallel lines of foredune ridges may
form. Less vigorous vegetation growth leads
to a less organized, hummocky appearance.
Very dense and vigorous vegetation can lead
to effective sediment trapping and vertical
dune growth. A steep nearshore slope probably
accentuates this form of dune growth by pre-
cluding seaward progradation. In the absence
of vegetation a transgressive sand sheet may
form, which migrates landward across pre-
existing features. Instability and vegetation
damage may lead to blowout formation on
vegetated dunes and, if persistent, will cause the
development of parabolic dunes that migrate
landward through the dune system. As a result,
dunes must be regarded not only in terms of
interactions between the beach and dune but
as dynamic systems in their own right in which
morphological change and sediment transfer
may proceed intermittently.
Eroding
cliff
f
Bay beach
Deep
embayment
Spit
Headland
Dune
Estuary
delta
Barrier
Tidal delta
Headland
tombolo
Bedrock
Lagoon
Salient
Bedrock island
Lagoon
Barrier island
Tidal delta
Coastal
plain
Spit
Beachridge plain
Sandy delta
Fig. 8.5 Temperate depositional landforms (headland-
embayment beach, spit, tombolo, salient, cuspate foreland,
barrier, barrier island).
the form of cuspate forelands (Fig. 8.6b) and
spits (Fig. 8.6d). Barrier islands are surrounded
on all sides by environments that are regularly
submerged. Thus a barrier island is fronted by
the open ocean and backed by a sheltered lagoon
(which may be marsh-filled). They are bounded
at either end by inlets that permit exchange of
water and sediment between the back-barrier
environment and the open sea.
Barriers enclose a marsh, lagoon or estuary and,
unlike barrier islands, are mainland-attached.
An inlet may or may not be present, through
which water flows between the back-barrier
system and the ocean. In some instances these
inlets are ephemeral or seasonal features depend-
ent on freshwater flow (Cooper 2001b). Inlets
on both barriers and barrier islands may or
may not contain flood- and ebb-tidal deltas. The
presence and morphology of tidal deltas are
controlled by the relative strengths of waves and
 
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