Journal of the Royal Society of Western Australia, 87(4), December 2004 
Figure 1. Idealised block diagram showing geomorphic units of the Swan Coastal Plain, their sub-parallelism to the Darling Scarp and 
the coast, their gross surface features, and their stratigraphy, with some details of landscape (after Semeniuk & Glassford 1989). The 
scope of this study involves only the Spearwood Dunes, Bassendean Dunes, and parts of the Pinjarra Plain. 
(Fig. 1). The linear wetlands of the Yalgorup Plain 
(Semeniuk 1995) of the central to southern Swan Coastal 
Plain will be the subject of a separate study. Wetlands 
within the Becher Suite of the Quindalup Dunes of the 
central Swan Coastal Plain also are the subject of a 
separate study (Semeniuk 2005), though for completeness 
brief mention is made in this paper of some of their 
deposits in terms of the nomenclature used herein. 
Beachridges and lunettes that have formed along the 
margins of wetland basins, and that have become 
emergent above the high-water mark are not treated as 
part of the wetland fill deposits in this paper. The 
sediments of fluvial wetlands and related features (i.e., 
channels and floodplains), whose landform surfaces 
range in age from Pleistocene to Holocene, as well as 
estuaries and linear lakes and lagoons formed leeward of 
marine-derived barriers also are not considered in this 
paper. Sedimentation in selected linear lagoons and 
estuaries marginal to the Swan Coastal Plain has already 
been described in Semeniuk & Semeniuk (1990), and 
Semeniuk (1996, 2000). 
Classification and terminology 
The wetland classification of Semeniuk (1987), 
developed for the central Swan Coastal Plain, is used in 
this paper. This classification uses the components of 
landform and hydrologic regime to develop wetland 
categories. As the emphasis in this paper is on basin 
wetlands, only the terms for these are noted here. 
Combining basin landform with hydrologic regime in the 
Swan Coastal Plain results in 3 categories of wetland: 1. 
permanently inundated basin = lake; 2. seasonally 
inundated basin = sumpland; and 3. seasonally 
waterlogged basin = dampland. Water and landform 
descriptors augment the primary categories. 
In this paper, the term intraclast is extended from the 
usage of Folk (1962), who coined it for intraformational 
clasts in carbonate depositional regimes, to refer to any 
reworked clasts of cemented, indurated, or dried 
sedimentary materials that belong to the cycle of 
sedimentation in which they are embedded. Intraclasts 
may be gravel sized to sand sized. The term 
intraformational describes production of particles that 
form within a given sedimentary formation. For example, 
the cementation, reworking into clasts, and incorporation 
of these clasts into extant sediments are intraformational 
phenomena. The term infiltrational describes deposits that 
form by infiltration into another sedimentary formation. 
For example, the delivery by vadose processes resulting 
in the accumulation of fine-grained sediments 
interstitially within another sedimentary body, rather 
than superposed on that body, is an infiltrational 
phenomenon. The term accrelionary describes deposits 
that accumulate vertically by superposition above 
another sedimentary formation. The term synscdimentary 
refers to processes that occur concurrently or 
penecontemporaneously with sedimentation. Burrowing 
by fauna, and root-structuring by vegetation, 
contemporaneous or penecontemporaneous with 
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