Sediment composition in fjords
Fjords are often found in high latitudes and mostly on
rocky shores. Fjords were created by the advance and
retreat of glacial ice during the quaternary, and as such,
they are immature systems that evolve and change over
short timescales. In fjords, sediments originating from
the continental shelf are less abundant that in other estuary
types (Syvitski and MacDonald, 1982). This is because
fjords typically contain one or more submarine sills that
act as very effective barriers to marine sediments and
because the compensation current is not near the bottom,
as in other estuaries, but closer to the surface and thus does
not lift sediments off the bottom and transport them up
fjord. A substantial flux of organic matter in fjords may
be linked to plankton that was transported into fjords by
the compensation current, leading to plankton blooms
(Petersen, 1978). According to Syvitski et al. (1987),
fjords are incredibly efficient sediment traps, having
retained around a quarter of the fluvial sediment delivered
to the oceans over the past 100,000 years.
Sediment composition in coastal lagoons
Coastal lagoons, or bar-built estuaries, may be found in
micro- and mesotidal coasts that are, or were in the near
past, dominated by littoral processes. Sea-level variations,
and the formation and growth of a lagoon barrier, play
a significant role in the development of coastal lagoons.
These features appear in coastal plains where a minor
change in sea level causes major land inundations (Emery,
1967). Lagoons may be bordered by land, tidal flats, salt
marshes, or mangroves, depending on the climate. Usually,
the sediments in coastal lagoons tend to contain a large
amount of organic matter. Seasonal, laminated muds dominate the bottom of template lagoons, except when the
lagoon is shallow enough to be altered by wind waves. Sand
content and wave action in coastal lagoons increase towards
inlets, where ripples, mega ripples, dunes, and sand waves
may form (Boothroyd, 1985). In addition, because of the
high biological content, flocs play an important role in the
sedimentary processes of coastal lagoons (Pejrup, 1988).
Summary
This contribution has focused on the sediment composition of estuaries. It has shown that all estuaries share some
common features in relation to the sediment composition
along and across the estuarine waterbody. However, this
composition will depend on the geographical location of
the estuary, on the estuary’s origin, on the relative contribution of different physical processes and sediment
sources, and on the landscape characteristics.
Bibliography
Bianchi, T. S., 2013. Estuaries: where the river meets the sea. Nature
Education Knowledge, 4(4), 12.
Bokuniewicz, H., 1995. Sedimentary systems of coastal-plain estuaries. In Perillo, G. M. E. (ed.), Geomorphology and
Sedimentology of Estuaries. Developments in Sedimentology.
Amsterdam: Elsevier, p. 471.
Boothroyd, J., 1985. Tidal inlets and tidal deltas. In Davis, R. A.
(ed.), Coastal Sedimentary Environments. New York: Springer,
pp. 445–532.
Castaing, P., and Guilcher, A., 1995. Geomorphology and sedimentology of rias. In Perillo, G. M. E. (ed.), Geomorphology and
Sedimentology of Estuaries. Developments in Sedimentology.
Amsterdam: Elsevier, p. 471.
Dalrymple, R. W., Zaitlin, B. A., and Boyd, R., 1992. Estuarine
facies models; conceptual basis and stratigraphic implications.
Journal of Sedimentary Petrology, 62, 1130–1146.
Dalrymple, R. W., 1992. Tidal depositional systems. In: Walker, R.
G., and James, N. P. (eds) Facies models; response to sea level
change. Geological Association of Canada. pp. 195–218.
Elliot, T., 1986. Deltas. In Reading, H. G. (ed.), Sedimentary Environments and Facies. Oxford: Blackwell Scientific Publications,
pp. 113–154.
Emery, K. O., 1967. Estuaries and lagoons in relation to continental
shelves. In Lauff, G. H. (ed.), Estuaries. Washington, DC:
AAAS, pp. 9–11.
Evans, G., and Prego, R., 2003. Rias, estuaries and incised valleys:
is a ria an estuary? Marine Geology, 196(3–4), 171–175.
Fairbridge, R. W., 1980. The estuary: its definition and geodynamic
cycle. In Olausson, E., and Cato, I. (eds.), Chemistry and Biogeochemistry of Estuaries. New York: Wiley, pp. 1–35.
Galloway, W. E., 1975. Process framework for describing the
morphologic and stratigraphic evolution of deltaic depositional
systems. In Broussard, M. L. (ed.), Deltas, Models for Exploration. Houston, TX: Houston Geological Society, pp. 87–98.
Goldring, D. W., Bosence, J., and Blake, T., 1978. Estuarine conditions in the Eocene of Southern England. Sedimentology, 25,
861–876.
Hart, B. S., 1995. Delta front estuaries. In Perillo, G. M. E. (ed.),
Geomorphology and Sedimentology of Estuaries. Developments
in Sedimentology. Amsterdam: Elsevier, p. 471.
Hayes, M. O., 1975. Morphology of sand accumulation in estuaries:
an introduction to the symposium. In Cronin, L. E. (ed.), Estuarine Research. New York: Academic Press, Vol. II, pp. 3–22.
Kinsman, B., and Pritchard, D. W., 1965. Lectures on Estuarine
Oceanography, delivered by D. W. Pritchard, October 3 -
December 4, 1960. Baltimore, Md: Chesapeake Bay Institute
and Dept. of Oceanography, Johns Hopkins University, 1965.
Nichols, M. M., and Biggs, R. B., 1985. Estuaries. In Davis, R. A.
(ed.), Coastal Sedimentary Environments. New York: Springer,
pp. 77–125.
Officer, C. B., 1981. Physical dynamics of estuarine suspended sediments. Marine Geology, 40, 1–14.
Orton, G. J., and Reading, H. G., 1993. Variability of deltaic processes in terms of sediment supply, with particular emphasis on
grain size. Sedimentology, 40, 475–512.
Pejrup, M., 1988. The triangular diagram used for classification of
estuarine environments: a new approach. In de Boer, P. L.,
et al. (eds.), Tide-Influenced Sedimentary Environments and
Facies. Dordrecht: Reidel Publishing Company, pp. 289–300.
Perillo, G. M. E., 1995. Definitions and geomorphologic classifications of estuaries. In Perillo, G. M. E. (ed.), Geomorphology and
Sedimentology of Estuaries. Developments in Sedimentology.
Amsterdam: Elsevier, p. 471.
Petersen, G. H., 1978. Life cycles and population dynamics of
marine benthic bivalves from the Disko Bugt area of West
Greenland. Ophelia, 17, 95–120.
Postma, G., 1990. Depositional architecture and facies of river and
fan deltas: a synthesis. In Collela, A., and Prior, D. B. (eds.),
Coarse-Grained Deltas. Spec. Publs Int. Ass. Sediment.,
10, 13–27.
Schumm, S. A., 1977. The Fluvial System. Toronto: Wiley, p. 338.
288
ESTUARINE SEDIMENT COMPOSITION
Fjords are often found in high latitudes and mostly on
rocky shores. Fjords were created by the advance and
retreat of glacial ice during the quaternary, and as such,
they are immature systems that evolve and change over
short timescales. In fjords, sediments originating from
the continental shelf are less abundant that in other estuary
types (Syvitski and MacDonald, 1982). This is because
fjords typically contain one or more submarine sills that
act as very effective barriers to marine sediments and
because the compensation current is not near the bottom,
as in other estuaries, but closer to the surface and thus does
not lift sediments off the bottom and transport them up
fjord. A substantial flux of organic matter in fjords may
be linked to plankton that was transported into fjords by
the compensation current, leading to plankton blooms
(Petersen, 1978). According to Syvitski et al. (1987),
fjords are incredibly efficient sediment traps, having
retained around a quarter of the fluvial sediment delivered
to the oceans over the past 100,000 years.
Sediment composition in coastal lagoons
Coastal lagoons, or bar-built estuaries, may be found in
micro- and mesotidal coasts that are, or were in the near
past, dominated by littoral processes. Sea-level variations,
and the formation and growth of a lagoon barrier, play
a significant role in the development of coastal lagoons.
These features appear in coastal plains where a minor
change in sea level causes major land inundations (Emery,
1967). Lagoons may be bordered by land, tidal flats, salt
marshes, or mangroves, depending on the climate. Usually,
the sediments in coastal lagoons tend to contain a large
amount of organic matter. Seasonal, laminated muds dominate the bottom of template lagoons, except when the
lagoon is shallow enough to be altered by wind waves. Sand
content and wave action in coastal lagoons increase towards
inlets, where ripples, mega ripples, dunes, and sand waves
may form (Boothroyd, 1985). In addition, because of the
high biological content, flocs play an important role in the
sedimentary processes of coastal lagoons (Pejrup, 1988).
Summary
This contribution has focused on the sediment composition of estuaries. It has shown that all estuaries share some
common features in relation to the sediment composition
along and across the estuarine waterbody. However, this
composition will depend on the geographical location of
the estuary, on the estuary’s origin, on the relative contribution of different physical processes and sediment
sources, and on the landscape characteristics.
Bibliography
Bianchi, T. S., 2013. Estuaries: where the river meets the sea. Nature
Education Knowledge, 4(4), 12.
Bokuniewicz, H., 1995. Sedimentary systems of coastal-plain estuaries. In Perillo, G. M. E. (ed.), Geomorphology and
Sedimentology of Estuaries. Developments in Sedimentology.
Amsterdam: Elsevier, p. 471.
Boothroyd, J., 1985. Tidal inlets and tidal deltas. In Davis, R. A.
(ed.), Coastal Sedimentary Environments. New York: Springer,
pp. 445–532.
Castaing, P., and Guilcher, A., 1995. Geomorphology and sedimentology of rias. In Perillo, G. M. E. (ed.), Geomorphology and
Sedimentology of Estuaries. Developments in Sedimentology.
Amsterdam: Elsevier, p. 471.
Dalrymple, R. W., Zaitlin, B. A., and Boyd, R., 1992. Estuarine
facies models; conceptual basis and stratigraphic implications.
Journal of Sedimentary Petrology, 62, 1130–1146.
Dalrymple, R. W., 1992. Tidal depositional systems. In: Walker, R.
G., and James, N. P. (eds) Facies models; response to sea level
change. Geological Association of Canada. pp. 195–218.
Elliot, T., 1986. Deltas. In Reading, H. G. (ed.), Sedimentary Environments and Facies. Oxford: Blackwell Scientific Publications,
pp. 113–154.
Emery, K. O., 1967. Estuaries and lagoons in relation to continental
shelves. In Lauff, G. H. (ed.), Estuaries. Washington, DC:
AAAS, pp. 9–11.
Evans, G., and Prego, R., 2003. Rias, estuaries and incised valleys:
is a ria an estuary? Marine Geology, 196(3–4), 171–175.
Fairbridge, R. W., 1980. The estuary: its definition and geodynamic
cycle. In Olausson, E., and Cato, I. (eds.), Chemistry and Biogeochemistry of Estuaries. New York: Wiley, pp. 1–35.
Galloway, W. E., 1975. Process framework for describing the
morphologic and stratigraphic evolution of deltaic depositional
systems. In Broussard, M. L. (ed.), Deltas, Models for Exploration. Houston, TX: Houston Geological Society, pp. 87–98.
Goldring, D. W., Bosence, J., and Blake, T., 1978. Estuarine conditions in the Eocene of Southern England. Sedimentology, 25,
861–876.
Hart, B. S., 1995. Delta front estuaries. In Perillo, G. M. E. (ed.),
Geomorphology and Sedimentology of Estuaries. Developments
in Sedimentology. Amsterdam: Elsevier, p. 471.
Hayes, M. O., 1975. Morphology of sand accumulation in estuaries:
an introduction to the symposium. In Cronin, L. E. (ed.), Estuarine Research. New York: Academic Press, Vol. II, pp. 3–22.
Kinsman, B., and Pritchard, D. W., 1965. Lectures on Estuarine
Oceanography, delivered by D. W. Pritchard, October 3 -
December 4, 1960. Baltimore, Md: Chesapeake Bay Institute
and Dept. of Oceanography, Johns Hopkins University, 1965.
Nichols, M. M., and Biggs, R. B., 1985. Estuaries. In Davis, R. A.
(ed.), Coastal Sedimentary Environments. New York: Springer,
pp. 77–125.
Officer, C. B., 1981. Physical dynamics of estuarine suspended sediments. Marine Geology, 40, 1–14.
Orton, G. J., and Reading, H. G., 1993. Variability of deltaic processes in terms of sediment supply, with particular emphasis on
grain size. Sedimentology, 40, 475–512.
Pejrup, M., 1988. The triangular diagram used for classification of
estuarine environments: a new approach. In de Boer, P. L.,
et al. (eds.), Tide-Influenced Sedimentary Environments and
Facies. Dordrecht: Reidel Publishing Company, pp. 289–300.
Perillo, G. M. E., 1995. Definitions and geomorphologic classifications of estuaries. In Perillo, G. M. E. (ed.), Geomorphology and
Sedimentology of Estuaries. Developments in Sedimentology.
Amsterdam: Elsevier, p. 471.
Petersen, G. H., 1978. Life cycles and population dynamics of
marine benthic bivalves from the Disko Bugt area of West
Greenland. Ophelia, 17, 95–120.
Postma, G., 1990. Depositional architecture and facies of river and
fan deltas: a synthesis. In Collela, A., and Prior, D. B. (eds.),
Coarse-Grained Deltas. Spec. Publs Int. Ass. Sediment.,
10, 13–27.
Schumm, S. A., 1977. The Fluvial System. Toronto: Wiley, p. 338.
288
ESTUARINE SEDIMENT COMPOSITION