Estuarine stratigraphic patterns will also depend on
hydrodynamic patterns, dispersal of sediments, estuarine
geometry, and factors which can result in cross-estuarine
heterogeneity or in facies asymmetry. For example, the
Leschenault Inlet Estuary of southwestern Australia,
a north–south-oriented shore-parallel estuarine lagoon, is
subject to southwesterly wind waves that rework its eastern shores such that it is sand-dominated, whereas the
western shore is spit, chenier, mud, and muddy sanddominated (Semeniuk, 2000). The Peel-Harvey Estuary
of southwestern Australia, mentioned above, provides
another example. Although functioning ecologically and
hydrochemically as a single estuary, it is geomorphically
a compound estuary. It has developed heterogeneous stratigraphy as a result of residing in a complex geological
framework, with local source materials, river dynamics,
fetch, and estuarine hydrodynamic processes (Semeniuk
and Semeniuk, 1990a). For instance, its shores facing
a long fetch are wave-dominated and composed of
prograded sandy beach ridges, while those sheltered from
the prevailing wave directions are mud-dominated. Also,
estuaries developed by marine flooding of a complex
meandering river on a coastal plain will result in
a geomorphically and sedimentologically complex estuary, with a resultant complex whole-of-estuary stratigraphy. In summary, the heterogeneous geometry, setting,
and internal features of estuaries may directly contribute
to a heterogeneous stratigraphy.
Thus, heterogeneity, complexity, and variability in an
estuary, in terms of shape, hydrodynamics (viz., river
vs. internal estuarine processes vs. magnitude of tides,
ocean waves, and wind), and sediment sources and volumes, will result in complex estuarine topography, internal geomorphology, and facies. For instance, in shoreparallel elongate estuary, with a sand supply from eroding
estuarine shores, and local sand (and not riverine sand),
under appropriate wind directions and wind waves, there
can be a major source of sediment transported alongshore
Stratigraphy of Estuaries, Figure 18 Longitudinal stratigraphic transect in the estuary of the Thames showing a mud-dominated
sequence, with local lenses of peat and sand (the stratigraphic section has been interpreted and constructed from information in
Morgan, 2006, and Khan et al., 2011)
STRATIGRAPHY OF ESTUARIES
639
hydrodynamic patterns, dispersal of sediments, estuarine
geometry, and factors which can result in cross-estuarine
heterogeneity or in facies asymmetry. For example, the
Leschenault Inlet Estuary of southwestern Australia,
a north–south-oriented shore-parallel estuarine lagoon, is
subject to southwesterly wind waves that rework its eastern shores such that it is sand-dominated, whereas the
western shore is spit, chenier, mud, and muddy sanddominated (Semeniuk, 2000). The Peel-Harvey Estuary
of southwestern Australia, mentioned above, provides
another example. Although functioning ecologically and
hydrochemically as a single estuary, it is geomorphically
a compound estuary. It has developed heterogeneous stratigraphy as a result of residing in a complex geological
framework, with local source materials, river dynamics,
fetch, and estuarine hydrodynamic processes (Semeniuk
and Semeniuk, 1990a). For instance, its shores facing
a long fetch are wave-dominated and composed of
prograded sandy beach ridges, while those sheltered from
the prevailing wave directions are mud-dominated. Also,
estuaries developed by marine flooding of a complex
meandering river on a coastal plain will result in
a geomorphically and sedimentologically complex estuary, with a resultant complex whole-of-estuary stratigraphy. In summary, the heterogeneous geometry, setting,
and internal features of estuaries may directly contribute
to a heterogeneous stratigraphy.
Thus, heterogeneity, complexity, and variability in an
estuary, in terms of shape, hydrodynamics (viz., river
vs. internal estuarine processes vs. magnitude of tides,
ocean waves, and wind), and sediment sources and volumes, will result in complex estuarine topography, internal geomorphology, and facies. For instance, in shoreparallel elongate estuary, with a sand supply from eroding
estuarine shores, and local sand (and not riverine sand),
under appropriate wind directions and wind waves, there
can be a major source of sediment transported alongshore
Stratigraphy of Estuaries, Figure 18 Longitudinal stratigraphic transect in the estuary of the Thames showing a mud-dominated
sequence, with local lenses of peat and sand (the stratigraphic section has been interpreted and constructed from information in
Morgan, 2006, and Khan et al., 2011)
STRATIGRAPHY OF ESTUARIES
639