Geoscience Reference
In-Depth Information
(b)
(a)
(+0.7)
Dornoch Firth
Zone of falling
sea level
Zone of falling
sea levels
(-3.7)
+0.4
Zone of
Isostatic
Uplift
Deeside
(-7.0)
-4.7
GLASGOW
Zone of
rising sea level
-2.4
Tyne
Te e s Bay
Zone of
rising sea levels
Solway Firth
-0.1
BELFAST
(+4.0)
+2.1
+0.6
Morecambe Bay
Humber
Lowlands
LIVERPOOL
+0.3
DUBLIN
+0.3
The Wash
Mersey
(2.0)
Dee
Norfolk
Broads
Essex
Marsh
Thames
Estuary
Romney
Marsh
General tendency for
rising sea level
(-0.3)
+1.7
+1.4
+1.5
Severn
Estuary
LONDON
(-3.2)
South Wales
Somerset
Levels
+5.4
+5.1
+4.1
Solent
+1.7
-0.3
Figure 17.11 The complex emergent/submergent nature of the British coastline, with residual isostatic recovery in Scotland
and submergence in south-east England in mm yr -1 , where most areas threatened by the rising sea level (black tone) are to be
found.
Source: Partly after Boorman et al. (1989)
also prone to subsidence through the compaction,
dewatering and isostatic depression of sediment under its
own weight. Predominantly low-energy, nutrient-fed
environments of the delta plain encourage highly produc-
tive floral and faunal ecosystems. As a result, fossil deltas
often contain hydrocarbon deposits. Modern biopro-
ductivity often encourages high-density but vulnerable
human populations, living at subsistence level, into areas
prone to regular and sometimes disastrous flooding.
Storm surges in the Ganges-Brahmaputra delta in
Bangladesh claimed 225,000 lives in November 1970 and
138,000 in April 1991.
Estuaries and lagoons
Estuaries and lagoons partially enclose saline and
freshwater bodies, dominated by fluvial or tidal processes.
Estuaries are the freshwater-fed, submerged lower reaches
of structural, river- or glacier-eroded valleys. They usually
lie orthogonal to the coastline. Lagoons impounded by
barriers are coast-parallel, the direct product of coastal
processes and are also river- and/or rain-fed. Both types
of embayment are classified by their water chemistry and
exchange processes. Stratification, or vertical separation,
occurs in estuaries lacking significant tidal or current
0
100
km
Figure 17.12 The archipelago of British islands which would
result from the complete melting of Antarctic ice, raising
global sea-levels by over 60 m.
 
 
 
 
 
 
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