Swift, D. J. P., and Field, M., 1981. Evolution of a classic sand
ridge field, Maryland sector, North America inner shelf.
Sedimentology, 28, 462–482.
Uchupi, E., 1968. Atlantic Continental Shelf and Slope of the United
States: Physiography. Washington, DC: US Government
Printing Office, 529-C, p. 30.
Veatch, A. C., and Smith, P. A., 1939. Atlantic Submarine Valleys of
the United States and the Congo Submarine Valley. Washington,
DC: Geological Society of America, 7, p. 101.
Cross-references
Bar
Barrier Island
Barrier Spits
Coastal Barriers
Coastal Landforms
Sedimentary Structures
SANDBANKS
Vanesa Magar
Oceanology Division/Department of Physical
Oceanography, CICESE, Ensenada, Mexico
Synonyms
Bank; Hummock; Ridge; Sands; Shoal
Definition
Sandbanks are bedforms consisting of cohesive or
non-cohesive sediments in estuaries and continental shelf
areas that can be exposed at low tide. They are generally
formed by sediment transport by tidal currents and waves
as well as changes of tidal prism due to sedimentation in
estuaries.
Description
Sandbanks have been the focus of an array of studies (e.g.,
Dyer and Huntley, 1999; Christopherson, 2002;
Chaumillon et al., 2008; Reeve et al., 2008; Brown and
Davies, 2009; Neill and Scourse, 2009). They mainly consist of sand particles with sizes varying from very coarse
(2 mm–1 m diameter) to very fine (0.10–0.05 mm) but
also can include silt (0.05–0.002 mm), clay
(<0.002 mm), and biological matter. Typical locations of
sandbanks are ebb and flood deltas of tidal inlets within
and in the vicinity of estuary mouths and near coastal
headlands.
Sandbanks generally form from tidal flows through
straits, past headlands and islands, where the currents are
rapid. At the ends of these features, the currents decrease,
and sediment deposition occurs. Sandbanks develop from
sand convergence driven by both tidal currents and waves.
In estuaries, sediment infilling causes the decrease in the
tidal prism on a century and millenia time scale, leading
to sandbank formation.
The location of sandbank formation has been used for
their classification. For example, sandbanks may be classified as open shelf linear sand ridges (Type 1), wide estuary sand ridges (Type 2A), ebb and flood deltas (Type
2Bi), shore attached ridges (Type 2Bii), banner banks
(Type 3A), and en-echelon ridges (Type 3B).
Sandbanks play a key role in natural coastal defenses
from waves (e.g., at the mouth of the Dyfi estuary in North
Wales), navigation, and as resources for sediment aggregates. Additionally, sandbanks are prime locations for offshore wind farm deployments in coastal regions. They are
also used as nesting grounds by sea lions and as feeding
and resting grounds by coastal birds such as seagulls and
oyster catchers.
There are many excellent examples of sandbanks.
Two of these in the UK include the Great Yarmouth sandbanks and the Isle of Portland sandbanks. The Great Yarmouth sandbanks may have been formed when the sea
transgressed from the south through the Dover Strait at
the end of the Holocene period. Some deep channels
between the sandbanks were also formed due to strong
tidal currents. Two of the major sandbanks of the Isle
of Portland (West Shoal and Adamant Shoal) may have
been formed when the Isle of Portland was isolated from
the mainland by a navigable strait. After sedimentation
caused the closure of the strait, these two sandbanks
were no longer actively maintained and subsequently
migrated towards the two largest present-day headland
sandbanks of the region (Portland Bank and
Shambles Bank).
Bibliography
Brown, J. M., and Davies, A. G., 2009. Methods for medium-term
prediction of the net sediment transport by waves and currents
in complex coastal regions. Continental Shelf Research, 29,
1502–1514.
Chaumillon, E., Bertin, X., Falchetto, H., Allard, J., Weber, N.,
Walker, P., Pouvreau, N., and Woppelmann, G., 2008. Multi
time-scale evolution of a wide estuary linear sandbank, the
Longe de Boyard, on the French Atlantic coast. Marine Geology,
251, 209–223.
Christopherson, R. W., 2002. Geosystems – An Introduction to
Physical Geography, 5th edn. New York: Prentice Hall.
Dyer, K. R., and Huntley, D. A., 1999. The origin, classification and
modeling of sand banks and ridges. Continental Shelf Research,
19, 1285–1330.
Neill, S.P., and Scourse, J. D., 2009. The formation of headland/
island sandbanks. Continental Shelf Research, 29, 2167–2177,
doi:10.1016/j.csr.2009.08.008#_blank.
Reeve, D. E., Horrillo-Caraballo, J. M., and Magar, V., 2008. Statistical analysis and forecasts of long-term sandbank evolution at
Great Yarmouth, UK. Estuarine, Coastal and Shelf Science,
79, 387–399.
Cross-references
Deltas
Mass Physical Sediment Properties
Sediment Transport
SANDBANKS
537
ridge field, Maryland sector, North America inner shelf.
Sedimentology, 28, 462–482.
Uchupi, E., 1968. Atlantic Continental Shelf and Slope of the United
States: Physiography. Washington, DC: US Government
Printing Office, 529-C, p. 30.
Veatch, A. C., and Smith, P. A., 1939. Atlantic Submarine Valleys of
the United States and the Congo Submarine Valley. Washington,
DC: Geological Society of America, 7, p. 101.
Cross-references
Bar
Barrier Island
Barrier Spits
Coastal Barriers
Coastal Landforms
Sedimentary Structures
SANDBANKS
Vanesa Magar
Oceanology Division/Department of Physical
Oceanography, CICESE, Ensenada, Mexico
Synonyms
Bank; Hummock; Ridge; Sands; Shoal
Definition
Sandbanks are bedforms consisting of cohesive or
non-cohesive sediments in estuaries and continental shelf
areas that can be exposed at low tide. They are generally
formed by sediment transport by tidal currents and waves
as well as changes of tidal prism due to sedimentation in
estuaries.
Description
Sandbanks have been the focus of an array of studies (e.g.,
Dyer and Huntley, 1999; Christopherson, 2002;
Chaumillon et al., 2008; Reeve et al., 2008; Brown and
Davies, 2009; Neill and Scourse, 2009). They mainly consist of sand particles with sizes varying from very coarse
(2 mm–1 m diameter) to very fine (0.10–0.05 mm) but
also can include silt (0.05–0.002 mm), clay
(<0.002 mm), and biological matter. Typical locations of
sandbanks are ebb and flood deltas of tidal inlets within
and in the vicinity of estuary mouths and near coastal
headlands.
Sandbanks generally form from tidal flows through
straits, past headlands and islands, where the currents are
rapid. At the ends of these features, the currents decrease,
and sediment deposition occurs. Sandbanks develop from
sand convergence driven by both tidal currents and waves.
In estuaries, sediment infilling causes the decrease in the
tidal prism on a century and millenia time scale, leading
to sandbank formation.
The location of sandbank formation has been used for
their classification. For example, sandbanks may be classified as open shelf linear sand ridges (Type 1), wide estuary sand ridges (Type 2A), ebb and flood deltas (Type
2Bi), shore attached ridges (Type 2Bii), banner banks
(Type 3A), and en-echelon ridges (Type 3B).
Sandbanks play a key role in natural coastal defenses
from waves (e.g., at the mouth of the Dyfi estuary in North
Wales), navigation, and as resources for sediment aggregates. Additionally, sandbanks are prime locations for offshore wind farm deployments in coastal regions. They are
also used as nesting grounds by sea lions and as feeding
and resting grounds by coastal birds such as seagulls and
oyster catchers.
There are many excellent examples of sandbanks.
Two of these in the UK include the Great Yarmouth sandbanks and the Isle of Portland sandbanks. The Great Yarmouth sandbanks may have been formed when the sea
transgressed from the south through the Dover Strait at
the end of the Holocene period. Some deep channels
between the sandbanks were also formed due to strong
tidal currents. Two of the major sandbanks of the Isle
of Portland (West Shoal and Adamant Shoal) may have
been formed when the Isle of Portland was isolated from
the mainland by a navigable strait. After sedimentation
caused the closure of the strait, these two sandbanks
were no longer actively maintained and subsequently
migrated towards the two largest present-day headland
sandbanks of the region (Portland Bank and
Shambles Bank).
Bibliography
Brown, J. M., and Davies, A. G., 2009. Methods for medium-term
prediction of the net sediment transport by waves and currents
in complex coastal regions. Continental Shelf Research, 29,
1502–1514.
Chaumillon, E., Bertin, X., Falchetto, H., Allard, J., Weber, N.,
Walker, P., Pouvreau, N., and Woppelmann, G., 2008. Multi
time-scale evolution of a wide estuary linear sandbank, the
Longe de Boyard, on the French Atlantic coast. Marine Geology,
251, 209–223.
Christopherson, R. W., 2002. Geosystems – An Introduction to
Physical Geography, 5th edn. New York: Prentice Hall.
Dyer, K. R., and Huntley, D. A., 1999. The origin, classification and
modeling of sand banks and ridges. Continental Shelf Research,
19, 1285–1330.
Neill, S.P., and Scourse, J. D., 2009. The formation of headland/
island sandbanks. Continental Shelf Research, 29, 2167–2177,
doi:10.1016/j.csr.2009.08.008#_blank.
Reeve, D. E., Horrillo-Caraballo, J. M., and Magar, V., 2008. Statistical analysis and forecasts of long-term sandbank evolution at
Great Yarmouth, UK. Estuarine, Coastal and Shelf Science,
79, 387–399.
Cross-references
Deltas
Mass Physical Sediment Properties
Sediment Transport
SANDBANKS
537