Postma, G., 1990. Depositional architecture and facies of river and
fan deltas: a synthesis. In Corella, A., and Prior, D. B. (eds.),
Coarse-Grained Deltas. Oxford: International Association of
Sedimentologists Special Publication, Vol. 10, pp. 13–27.
Pritchard, D. W., 1967. What is an estuary: physical viewpoint.
In Lauf, G. H. (ed.), Estuaries. Washington, DC: American Association for the Advancement of Science Publication, Vol. 83, pp. 3–5.
Reineck, H. E., and Singh, I. B., 1980. Depositional Sedimentary
Environments, 2nd edn. Berlin: Springer.
Scruton, P. C., 1960. Delta building and the deltaic sequence. In
Shepard, F. P., Phleger, F. B., and van Andel, T. H. (eds.), Recent
Sediments, Northwest Gulf of Mexico. Tulsa: American Association of Petroleum Geologists, pp. 82–102.
Semeniuk, V., 2000. Sedimentology and Holocene stratigraphy of
Leschenault Inlet. Journal of the Royal Society of Western Australia, Special Issue on the Leschenault Inlet Estuary, 83, 255–274.
Semeniuk, C. A., and Semeniuk, V., 1990a. The coastal landforms
and peripheral wetlands of the Peel-Harvey estuarine system.
Journal of the Royal Society of Western Australia, 73, 9–21.
Semeniuk, V., and Semeniuk, C. A., 1990b. Radiocarbon ages of
some coastal landforms in the Peel-Harvey estuary. Journal of
the Royal Society of Western Australia, 73, 61–71.
Semeniuk, V., Semeniuk, C. A., Tauss, C., Unno, J., and Brocx, M.,
2011. Walpole and Nornalup Inlets: Landforms, Stratigraphy, Evolution, Hydrology, Water Quality, Biota, and Geoheritage. Perth:
Western Australian Museum. 584 p. ISBN 978-1-920843-37-3.
Summerhayes, C. P., Sestini, G., Misdorp, R., and Marks, N., 1978.
Nile Delta: nature and evolution of continental shelf sediments.
Marine Geology, 27, 43–65.
van Heerden, I., and Roberts, H. H., 1988. Facies development
Atchafalaya delta, Louisiana: a modern bayhead delta. American
Association of Petroleum Geologists, 72, 439–453.
Wright, L. D., 1978. Chapter 1: River deltas. In Davis, R. A. (ed.),
Coastal Sedimentary Environments. New York: Springer, pp. 5–68.
Wright, L. D., and Coleman, J. M., 1973. Variation in morphology
of major river deltas as functions of ocean waves and river discharge regimes. Bulletin of the American Association of Petroleum Geologists, 57, 370–398.
Cross-references
Delta Plain
Estuarine Deltaic Wetlands
Estuarine Geomorphology
Sediment Erosion
Shoreline Changes
Species Zonation
Stratigraphy of Estuaries
Tidal Hydrodynamics
DENSITY STRATIFICATION
Geórgenes H. Cavalcante
Institute of Atmospheric Science, Federal University of
Alagoas, Maceió, Alagoas, Brazil
Definition
Density stratification can be defined as the vertical
distribution of water masses into separate, distinct
horizontal layers as a result of differences in density.
These differences can also be attributed to differences
throughout the water layers in dissolved solids, temperature, or suspended solids.
Description
The density stratification is extremely sharp, so that pure
freshwater and pure saltwater are vertically adjacent. Such
conditions can increase as density increases with depth
and then the greater the vertical gradient will be, resulting
in higher stability of the stratification.
Variations in the distribution of ocean density control
the large-scale movements of water masses, and are
important features in the dynamics of ocean surface currents, and drive the circulation of estuaries (Kjerfve,
1979). The less dense freshwater has a tendency to remain
primarily in the surface layers. In estuaries where the tidal
range is small, the tidal energy is limited during neap tides,
and the water column becomes stratified vertically
because of denser bottom water and a less dense surface
layer.
In the North Atlantic Gyre, there are four distinct water
masses that resulted from density stratification, creating
interconnected currents with different flow characteristics
and temperature: North Equatorial Current (NEC), North
Atlantic Current (NAC), Gulf Stream (GS), and Canary
Current (CC) (Talley et al., 2011).
Bibliography
Kjerfve, B., 1979. Measurement and analysis of water current, temperature, salinity, and density. In Dyer, K. R. (ed.), Hydrography
and Sedimentation in Estuaries. Cambridge: Cambridge University Press, pp. 186–216.
Talley, L. D., Pickard, G. L., Emery, W. J., and Swift, J. H., 2011.
Descriptive Physical Oceanography: An Introduction. Amsterdam: Elsevier Science.
Cross-references
Estuarine Circulation
Residual Circulation
River-Dominated Estuary
Tidal Hydrodynamics
DETERMINING GEOHERITAGE VALUES
Margaret Brocx
1 and Vic Semeniuk
2
1
Department of Environmental Science, Murdoch
University, Murdoch, WA, Australia
2
V & C Semeniuk Research Group, Warwick, WA,
Australia
Definitions
Geoheritage. The heritage value assigned to features of
a geological nature encompasses globally, nationally,
statewide to regionally, and locally significant features of
earth science that are intrinsically important or culturally
important, offering information or insights into the
DETERMINING GEOHERITAGE VALUES
187
fan deltas: a synthesis. In Corella, A., and Prior, D. B. (eds.),
Coarse-Grained Deltas. Oxford: International Association of
Sedimentologists Special Publication, Vol. 10, pp. 13–27.
Pritchard, D. W., 1967. What is an estuary: physical viewpoint.
In Lauf, G. H. (ed.), Estuaries. Washington, DC: American Association for the Advancement of Science Publication, Vol. 83, pp. 3–5.
Reineck, H. E., and Singh, I. B., 1980. Depositional Sedimentary
Environments, 2nd edn. Berlin: Springer.
Scruton, P. C., 1960. Delta building and the deltaic sequence. In
Shepard, F. P., Phleger, F. B., and van Andel, T. H. (eds.), Recent
Sediments, Northwest Gulf of Mexico. Tulsa: American Association of Petroleum Geologists, pp. 82–102.
Semeniuk, V., 2000. Sedimentology and Holocene stratigraphy of
Leschenault Inlet. Journal of the Royal Society of Western Australia, Special Issue on the Leschenault Inlet Estuary, 83, 255–274.
Semeniuk, C. A., and Semeniuk, V., 1990a. The coastal landforms
and peripheral wetlands of the Peel-Harvey estuarine system.
Journal of the Royal Society of Western Australia, 73, 9–21.
Semeniuk, V., and Semeniuk, C. A., 1990b. Radiocarbon ages of
some coastal landforms in the Peel-Harvey estuary. Journal of
the Royal Society of Western Australia, 73, 61–71.
Semeniuk, V., Semeniuk, C. A., Tauss, C., Unno, J., and Brocx, M.,
2011. Walpole and Nornalup Inlets: Landforms, Stratigraphy, Evolution, Hydrology, Water Quality, Biota, and Geoheritage. Perth:
Western Australian Museum. 584 p. ISBN 978-1-920843-37-3.
Summerhayes, C. P., Sestini, G., Misdorp, R., and Marks, N., 1978.
Nile Delta: nature and evolution of continental shelf sediments.
Marine Geology, 27, 43–65.
van Heerden, I., and Roberts, H. H., 1988. Facies development
Atchafalaya delta, Louisiana: a modern bayhead delta. American
Association of Petroleum Geologists, 72, 439–453.
Wright, L. D., 1978. Chapter 1: River deltas. In Davis, R. A. (ed.),
Coastal Sedimentary Environments. New York: Springer, pp. 5–68.
Wright, L. D., and Coleman, J. M., 1973. Variation in morphology
of major river deltas as functions of ocean waves and river discharge regimes. Bulletin of the American Association of Petroleum Geologists, 57, 370–398.
Cross-references
Delta Plain
Estuarine Deltaic Wetlands
Estuarine Geomorphology
Sediment Erosion
Shoreline Changes
Species Zonation
Stratigraphy of Estuaries
Tidal Hydrodynamics
DENSITY STRATIFICATION
Geórgenes H. Cavalcante
Institute of Atmospheric Science, Federal University of
Alagoas, Maceió, Alagoas, Brazil
Definition
Density stratification can be defined as the vertical
distribution of water masses into separate, distinct
horizontal layers as a result of differences in density.
These differences can also be attributed to differences
throughout the water layers in dissolved solids, temperature, or suspended solids.
Description
The density stratification is extremely sharp, so that pure
freshwater and pure saltwater are vertically adjacent. Such
conditions can increase as density increases with depth
and then the greater the vertical gradient will be, resulting
in higher stability of the stratification.
Variations in the distribution of ocean density control
the large-scale movements of water masses, and are
important features in the dynamics of ocean surface currents, and drive the circulation of estuaries (Kjerfve,
1979). The less dense freshwater has a tendency to remain
primarily in the surface layers. In estuaries where the tidal
range is small, the tidal energy is limited during neap tides,
and the water column becomes stratified vertically
because of denser bottom water and a less dense surface
layer.
In the North Atlantic Gyre, there are four distinct water
masses that resulted from density stratification, creating
interconnected currents with different flow characteristics
and temperature: North Equatorial Current (NEC), North
Atlantic Current (NAC), Gulf Stream (GS), and Canary
Current (CC) (Talley et al., 2011).
Bibliography
Kjerfve, B., 1979. Measurement and analysis of water current, temperature, salinity, and density. In Dyer, K. R. (ed.), Hydrography
and Sedimentation in Estuaries. Cambridge: Cambridge University Press, pp. 186–216.
Talley, L. D., Pickard, G. L., Emery, W. J., and Swift, J. H., 2011.
Descriptive Physical Oceanography: An Introduction. Amsterdam: Elsevier Science.
Cross-references
Estuarine Circulation
Residual Circulation
River-Dominated Estuary
Tidal Hydrodynamics
DETERMINING GEOHERITAGE VALUES
Margaret Brocx
1 and Vic Semeniuk
2
1
Department of Environmental Science, Murdoch
University, Murdoch, WA, Australia
2
V & C Semeniuk Research Group, Warwick, WA,
Australia
Definitions
Geoheritage. The heritage value assigned to features of
a geological nature encompasses globally, nationally,
statewide to regionally, and locally significant features of
earth science that are intrinsically important or culturally
important, offering information or insights into the
DETERMINING GEOHERITAGE VALUES
187