Geology Reference
In-Depth Information
Table 3
(continued)
Geological feature
Type of site, and its scale (category of site from
Fig.
1
)
Signi
cance
Rationale for assigning the level of signi
cance
Intra-estuarine deltas
Geohistorical sites and modern landscapes and
setting (active processes); reference sites; large
scale feature
National
Three rivers drain into the estuary creating intra-estuarine deltas that are distinct to
Western Australia; the deltas in different hydrodynamic settings; the deltas are
variably exposed to wave actions, or tides or are dominated by uvial
processes and this has resulted in variable delta forms that are dependent on the
estuarine setting of a given delta
Asymmetric, heterogeneous, and
polygenetic nature of the intra-
estuarine deltas
Geohistorical sites and modern landscapes and
setting (active processes); reference sites; large
scale feature
International
Each of the three deltas in their different hydrodynamic settings have produced
distinctively different forms in terms of their asymmetry, heterogeneity, and
polygenetic nature; the deltas re
ect their asymmetric formation depending on
whether their components are wave-dominated, tide-dominated, or
uvially
dominated
The tidal delta
Modern landscapes and setting (active processes);
reference sites; medium scale feature
State-wide
The entrance inlet of the estuary has produced a large and distinctive
ood-tidal
delta unique in form and size in Western Australia
Wetlands along the estuary
margin
Modern landscapes and setting (active processes);
reference sites; Medium scale feature
National
In this most humid part of Western Australia, this estuarine system is bordered by
wetlands (mainly paluslopes) that are variable in form and dynamics dependent
on estuarine setting; in the humid climate, the wetlands are underlain by peat;
the ensemble of wetlands bordering this estuary and their peat deposits are
unique to this part of Western Australia
Lake within the Circus Beach
Barrier
Modern landscapes and setting (active processes);
reference sites; medium scale feature
State-wide
The dune lake in the Circus Beach Barrier, formed by wind de
ation and water
table rise, is a unique landform to coastal Western Australia
Mean sea level history
Geohistorical site; small scale feature
State-wide
There is a unique local Holocene sea level history recorded in the shallow marine
deposits in this area that is different to the rest of coastal Western Australia
stratigraphic type sections
geohistorical site; small scale feature
State-wide
The area contains a number of stratigraphic type sections
Features of special interest
Geohistorical site; small scale feature
Regional, to
State-wide
signicance
There are number of signicant geological features of special interest in this
estuarine area; these are: peat capping the deltaic sequences in all three deltas;
peat formed in response to subartesian upwelling the occurrence of in situ
polychaete and mollusc assemblages stranded 1 m above their current
environment; saprolitic gneiss in the cliffs; and local palaeosols (see Semeniuk
et al. (
2011
) for more details)
