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Data density map for the offshore component of the DRM, expressed in data points per km2. The scale is logarithmic and shows that the seabed component of the DRM predominantly has data densities of 102–105 data points per km2. The areas of multibeam sonar coverage have the highest density of soundings.
Source publication
A digital relief model (DRM) of the Swan Coastal Plain and Rottnest Shelf (7400 km2) was built with a range of topographic and high-resolution bathymetric datasets, gridded to a 50 m cell size. The DRM enabled the delineation of relict coastal landforms, benthic habitats and development of a regional morphostratigraphic framework. Well-defined feat...
Citations
... While it is becoming well documented that nonreefal accumulations, such as stacked aeolianites and beachrocks, also have the ability to form bathymetric highs on the modern seafloor (e.g., Brooke et al., 2017;Bufarale et al., 2019;Green et al., 2020;Lebrec et al., 2022aLebrec et al., , 2022bO'Leary et al., 2020;Passos et al., 2019) and can misleadingly exhibit reefal morphologies in seismic-reflection data (Bubb & Hatlelid, 1977;Salzmann et al., 2013), pre-Quaternary carbonate aeolianites and other relict coastal features are rarely documented in the geologic literature (e.g., Abegg & Handford, 2001;Dodd et al., 2001;Kindler & Davaud, 2001;McKee & Ward, 1983;Smith et al., 2001), and non-reefal carbonate buildups are seldom described by seismic interpreters. This is particularly puzzling given the ability of drowned coastal features to exhibit buildup morphologies and to form both carbonate and siliciclastic barrier complexes-composed of beachrocks, aeolianites and other coastal sedimentary deposits preserved through early cementation-forming seafloor ridges enclosing lagoons, bays or estuaries (e.g., Alcántara-Carrió et al., 2013;Brooke et al., 2010;De Falco et al., 2015;Gardner et al., 2007;Lebrec et al., 2022a;Locker et al., 1996;Mellett et al., 2012;Passos et al., 2019;Sade et al., 2006;Wenau et al., 2020). As an example, the islands of the Bahamas are largely formed by aeolianites (Carew & Mylroie, 2001;Nelson, 1853). ...
... (Gardner et al., 2005;Figure 9). Examples of drowned non-reefal ridges that form such structures on the present-day seafloor are numerous (e.g., Alcántara-Carrió et al., 2013;Brooke et al., 2010;De Falco et al., 2015;Lebrec et al., 2022aLebrec et al., , 2022bMellett et al., 2012;Wenau et al., 2020), and they should be considered as possible analogues for seafloor ridges observed along continental shelves. Additionally, identification of corals or other reefbuilding organism on the inside part of a ridge is not infallible evidence of a reefal origin, as loose corals or other sessile organisms can also be reworked to form ridges (e.g., Spiske, 2016), which may lead to their misinterpretation as a bioconstructed ridge. ...
Linear buildups formed in tropical carbonate environments are often interpreted as bioconstructed reefs. Nevertheless, coastal processes can also form extensive sedimentary ridges exhibiting buildup morphologies. This study investigates two Miocene ridges developed along the Australian North West Shelf using 3D seismic and well data. Ridge 1 is ca. 30 m thick and >60 km long, and it is made of foraminiferal pack‐grainstones. It protects a lagoon with pinnacle morphologies. Ridge 2 is ca. 150 m thick and >80 km long. It is composed of quartz sand forming lobes. Both ridges have a continuous curvilinear front and are in a mid‐shelf setting. They mimic the modern Australian coastline. It is then proposed that Ridge 1 is either: (1) a barrier reef developed on a drowned shoreline, or (2) stacked carbonate aeolianites and beachrocks acting as a barrier. Ridge 2 is interpreted as stacked deltaic sands. This study demonstrates that lithified and buried coastal features of carbonate and siliciclastic nature can form extensive ridges exhibiting buildup morphologies. It is proposed that ridges formed by stacked coastal features are overall continuous with a curvilinear front, while reefal ridges are more discontinuous and exhibit deeper and more stable passes.
... The base of the ridge typically represents the maximum height of constructive waves (Fig. 2B, Tamura, 2012). Extensive submerged wind-built ridges were reported in: (1) the Mediterranean Sea (Goff et al., 2018;Gzam et al., 2016;Mart and Belknap, 1991;Micallef et al., 2013;Sade et al., 2006); (2) eastern South Africa (Cawthra et al., 2013;Green et al., 2012;Green et al., 2013;Green et al., 2017;Martin and Flemming, 1986;Pretorius et al., 2016;Pretorius et al., 2019;Ramsay, 1994;Salzmann et al., 2013); (3) Mozambique (Wenau et al., 2020); (4) Australia (Beaman et al., 2005;Brooke et al., 2010;Brooke et al., 2014;Nicholas et al., 2014;O'Leary et al., 2020;Passos et al., 2019;Sprigg, 1979); (5) India (Rao et al., 2001); (6) Florida (Finkl and Andrews, 2008;Gardner et al., 2007;Jarrett et al., 2005;Locker et al., 1996); (7) Bermuda (Stanley and Swift, 1967); and (8) Turkey (Ocakoglu et al., 2018). Submerged wind-built beach ridges exhibit a large variety of sizes, with heights ranging from a few to tens of meters, spanning over areas of hundreds to thousands of meters. ...
Palaeoshorelines and associated palaeo-coastal features are studied to reconstruct past sea level, climate, and depositional environments. Their identification typically depends on direct field observations and is therefore challenging in marine environment, where the interpretation mostly relies on sparse geophysical data. This review presents, based on 118 published case studies, a summary of morphological evidences that can be used to identify submerged relict coastal features worldwide, using only geophysical data. Four coastal feature categories that can be used as palaeoshoreline indicators were identified: (1) beach ridges of wind and wave origin; (2) shoreface strata; (3) marine terraces; and (4) coral-reef terraces.
In light of this proposed classification, an area of ~200,000 km² was investigated along the Rowley Shelf (North West Shelf, Australia), a carbonate-dominated platform, based on the integration of high-resolution bathymetry (i.e., seismic-derived bathymetry, satellite-derived bathymetry, multibeam echosounder bathymetry, spot depth soundings) and 2D reflection seismic lines. Relict features were discriminated from modern bedforms using five criteria: (1) stratigraphic position; (2) emersion features; (3) similarity with modern and published analogues; (4) integration of modern ocean conditions; and (5) evidence of early cementation. In total, over 500 submerged relict coastal features were identified, making this review the most comprehensive catalogue published to date.
Relict features are concentrated over specific depths, referred to as modal sea-level depths (MSLDs), which correspond to depths where the relative sea level remained stable over long periods of time. Nine MSLDs are observed at 20, 35, 50, 60, 70, 80, 90, 105 and 125 m below sea level. Each MSLD is the result of the accumulation of coastal features through multiple glacial/ interglacial cycles. Most of the features may nevertheless be related to the last glacial sea-level fall and were likely formed between Marine Isotopes Stages (MIS) 5 and 2.
The analysis of the submerged coastal features indicates that the overall shelf morphology is controlled by the repartition of these features, and that, while in a carbonate province, their formation is related to wind, tide, fluvial and wave processes. The higher concentration of fluvial relict features at shallower depths and of tide-influenced relict features at greater depths suggest that fluvial runoffs were limited during glacial periods. This, in turn, supports the hypothesis of a prevalent dry climate during glacial periods and in contrast, of a humid climate during interglacial periods. Finally, the study reveals that most of modern coral reefs of the Rowley Shelf are growing on top of relict coastal features and that seabed ridges previously interpreted as drowned coral reefs are, in fact, likely to be relict coastal features formed through clastic processes.
Results from this study will support the identification of submerged palaeoshorelines on continental shelves around the globe and highlight the influence of associated relict coastal features on shelf morphologies. Additionally, this study provides new insights on processes shaping carbonate provinces.
... The remnant submerged Pleistocene paleoenvironments revealed from the highresolution 3D seismic surveys are similarly complex and highly productive, with human settlement pattern behaviour likely responding to these evolving coastal environments. The shoreline barrier feature (Fig. 7) similarly has a modern analogue in the Swan Coastal Plain (Semeniuk, 2000;Brooke et al., 2010), which Dortch and Dortch (2012) describe as a dune landscape, marked from west to east by a gradual lessening in topographic relief and an increase in biologically diverse terrestrial habitats. However, in this setting the most common archaeological site type is artefact scatters on the surface, in dune depressions and buried beneath dunes (Dortch and Dortch, 2012). ...
Almost 2 million square km of Australia’s continental shelf was flooded following the termination of the last glacial maximum, and with it the cultural heritage of the first arrival and coastal occupation of Australia beginning some 65,000 years ago. In order to prospect for this missing cultural record, we must first identify submerged coastal landscapes and landforms that likely provided favourable environments for occupation and resource use. However, this task is challenged by the sheer size of the Australian continental margin. To help address this, we use industry 3D seismic datasets, that cover vast areas of Australia’s continental shelf, to map seafloor bathymetry at high resolution (10–25 m). Our study focuses an area of 6500 square km on the mid/outer shelf regions proximal to Barrow Island. The 3D seismic bathymetry revealed a highly complex and geomorphically mature coastal landscape preserved at depths of 70–75 m below sea level, including coastal barrier dunes, lagoonal systems, tidal flats and estuarine channels. Based on the depth of the submerged shorelines and reconstructed sea level curves, the age range of these coastal landforms is constrained to Marine Isotope Stage 3 (57–29 ka), which overlaps with the known onset of occupation at Barrow Island and the wider Carnarvon bioregion and the adjacent Pilbara. Such feature preservation has significant geoheritage value, but also allows for human behavioural ecology modelling and provides targets for future dating and site survey.
... Since no dating has been undertaken for this research, the following interpretation was performed using pre-existing literature, including Wallace and Kimber (1989); Kendrick et al. (1991); Gozzard (2007); Brooke (2010) and Mathew (2010). ...
A high-resolution seismic survey was carried out across the metropolitan reach of the Swan River (Perth, Western Australia) to investigate its Late Quaternary sub-surficial geomorphology. Shallow imaging data, integrated with sediment cores, pre-existing literature (including dating) and LiDAR images, revealed three main units, forming a complex system of buried paleochannels, which developed during the Late Quaternary glacial sea level lowstands, and infilled during interglacial highstands.
The deepest unit was interpreted as comprising estuarine to fluvial sediments of the Perth Formation, deposited during the Last Interglacial (~130-80 thousand years before present) in a wide paleo-valley that cut the basement.
The sedimentary sequence of the overlaying middle unit belongs to the Swan River Formation, which consists of heterogenic fluvial to lacustrine sediments, deposited during the Last Glacial lowstand (~80-18 thousand years before present).
The shallowest unit comprises Holocene fluvial and estuarine sediments, up to ten-thousand-year-old.
This research represents the first environmental high-resolution acoustic investigation of the Swan River estuary. The findings have improved the understanding of the Late Quaternary Swan River development, providing a useful tool for modelling river onset and evolution, following sea level transgressions.
... The lithology and age of inner shelf deposits were inferred from previous investigations from Geographe Bay to Rottnest Island (including the Swan Coastal Plain; e.g., Probert 1967;Playford et al. 1976;Wharton 1981Wharton , 1982Commander 1982;Hirschberg 1988Hirschberg , 1989Deeney 1989;Collins and Baxter 1984;Hamilton & Collins 1997;Schafer et al. 2008;Brooke et al. 2010Brooke et al. , 2014 because coring and dating was not part of the present study. Interpretation of the geomorphological features is supported by the findings of Brooke et al. (2010Brooke et al. ( , 2014 who carried out an extensive morphostratigraphic investigation of shore-parallel, relict barriers and ridges between Hillarys (30 km north of Rottnest Island) and Cockburn Sound (up to 34 km south of Rottnest Island), using bathymetric and topographic digital relief models and previously acquired dating (from Price et al. 2001 andHearty 2003). ...
... The lithology and age of inner shelf deposits were inferred from previous investigations from Geographe Bay to Rottnest Island (including the Swan Coastal Plain; e.g., Probert 1967;Playford et al. 1976;Wharton 1981Wharton , 1982Commander 1982;Hirschberg 1988Hirschberg , 1989Deeney 1989;Collins and Baxter 1984;Hamilton & Collins 1997;Schafer et al. 2008;Brooke et al. 2010Brooke et al. , 2014 because coring and dating was not part of the present study. Interpretation of the geomorphological features is supported by the findings of Brooke et al. (2010Brooke et al. ( , 2014 who carried out an extensive morphostratigraphic investigation of shore-parallel, relict barriers and ridges between Hillarys (30 km north of Rottnest Island) and Cockburn Sound (up to 34 km south of Rottnest Island), using bathymetric and topographic digital relief models and previously acquired dating (from Price et al. 2001 andHearty 2003). Several shallow cores (up to 6 m long) cut within Cockburn Sound (about 100 km north of the survey area) by Skene et al. (2005) provide valuable insights into the sub-seafloor deposits of south-west Australia and were used to support the interpretation of the shallow stratigraphy proposed in this study. ...
... The Rottnest Shelf, defined by Carrigy & Fairbridge (1954), can be subdivided into three main bathymetric provinces: (1) the Inner Shelf, which extends from 0 to 100 m in depth, where submerged terraces and ridges formed during past periods of low sea level (Fig. 1); (2) the Outer Shelf that ends with the shelf-slope break at 170 m; and (3) the Upper Continental Slope (Collins 1988). Traces of subaerial erosion are recognisable in remnant subaqueous features such as reefs, shore-parallel ridges and barrier-dune systems (Collins 1988;Playford 1997;Brooke et al. 2010). ...
High-resolution shallow seismic profiles collected along the inner shelf in Geographe Bay (south-west Australia) illustrate a highly-variable buried architecture. Three main acoustic units, separated by unconformities, correspond to different geological facies, deposited under various sea-level conditions. The acoustic basement (Unit B) belongs to the Lower Cretaceous Leederville Formation; the middle unit is attributable to the Tamala Limestone (Unit P, Mid-to Late Pleistocene) and the top unit (Unit H) is Holocene. Combining the seismic data with high-resolution bathymetry and sediment grabs, several surficial and buried morphological features are revealed, including sandbars, palaeochannels and ridges. The shore-oblique sandbars have been directly influenced by local hydrodynamics including mean wave direction and currents, benthic habitats such as seagrass, and sediment grain size. The palaeochannels (buried and surficial) are the expression of previous sea-level lowstands. Two sets of shore-parallel, low-relief ridges, at depths of ~7 m and ~20 m, are relict landforms that are most likely regressive beach ridges and sub-littoral deposits, belonging to the Tamala Limestone. These structures were formed during Late Pleistocene relatively high sea-level stages (late Marine Isotope Stages 5e and 5c, respectively, between 120 and 100 thousand years ago), cemented when the sea level was lower and subsequently subject to transgressive erosion. The newly acquired seismic datasets shows that the inner shelf is mostly covered by a veneer of sediment (with average thickness of 50 cm) above the Pleistocene hard surface, whereas sandbars can be up to 6 m thick.
... Remote survey and physical sampling indicate that during Pleistocene low sea levels the shelf was carbonate sand plain featuring on its seaward edge a dune barrier, and eastward a succession of dune ridges aligned along former shorelines. Today's limestone reefs and islands are relicts of the coastal dune barrier (Brooke et al. 2010(Brooke et al. , 2014Nicholas et al. 2013Nicholas et al. , 2014Playford 1997). A few kilometres north of the Rottnest pre-island locality, the ancestral Swan River Estuary traversed the emergent shelf before entering the Perth Canyon incised into the shelf edge (Playford 1983:14). ...
The Greater Swan Region is an archaeological study area on the Indian Ocean coast in south-western Australia. It covers the central Swan Coastal Plain and the adjacent part of the formerly emergent Rottnest Shelf. Assessment of Aboriginal hunter-gatherer activity throughout this late Quaternary coastal landscape is based on dated records of open-air sites within their environmental settings, informed by historical accounts of mainland subsistence activities. Artefacts flaked from Eocene fossiliferous chert and other stone, identified, in situ, in dated dune soils on the mainland and in palaeosols and Tamala Limestone successions on Rottnest Island, show that during regressive sea levels human groups were distributed across a sand plain reaching from the Darling Scarp 70 km westward across the emergent Rottnest Shelf. On the mainland, open-air site settings near freshwater sources and terrestrial and estuarine habitats give insight into adaptive strategies of Aboriginal occupiers. A similar occupation pattern is proposed for the emergent shelf. Early Holocene records of terrestrial plant species and freshwater microfauna from Barker Swamp on Rottnest Island imply that freshwater sources and terrestrial habitats were comparable to those of the mainland. Further archaeological investigations on the Rottnest Shelf should include extant and former freshwater swamps on Rottnest Island.
... In Western Australia, investigations by Playford et al. (1976Playford et al. ( , 2013, Playford (1988Playford ( , 1997, Price et al. (2001), Brooke et al. (2014), and Ward et al. (2016) show that aeolianites were deposited during interglacial, interstadial, and glacial periods. Aeolianite formation during interstadial or glacial periods off the coast of Western Australia, when sea level was below present, is supported by mapping, submarine exploration, and sonar work that demonstrate the presence of these deposits offshore (Brooke et al. 2010(Brooke et al. , 2017Nichol and Brooke 2011). In South Africa, optically stimulated luminescence (OSL) dating also indicates that aeolianite deposition has a complex timing, occurring during interglacial, interstadial, and glacial periods (Bateman et al. 2004(Bateman et al. , 2011Porat and Botha 2008;Roberts et al. 2008;Carr et al. 2010). ...
Along most of the Pacific Coast of North America, sand dunes are dominantly silicate-rich. On the California Channel Islands, however, dunes are carbonate-rich, due to high productivity offshore and a lack of dilution by silicate minerals. Older sands on the Channel Islands contain enough carbonate to be cemented into aeolianite. Several generations of carbonate aeolianites are present on the California Channel Islands and represent the northernmost Quaternary coastal aeolianites on the Pacific Coast of North America. The oldest aeolianites on the islands may date to the early Pleistocene and thus far have only been found on Santa Cruz Island. Aeolianites with well-developed soils are found on both San Miguel Island and Santa Rosa Island and likely date to the middle Pleistocene. The youngest and best-dated aeolianites are located on San Miguel Island and Santa Rosa Island. These sediments were deposited during the late Pleistocene following the emergence of marine terraces that date to the last interglacial complex (∼. 120,000. yr to ∼. 80,000. yr). Based on radiocarbon and luminescence dating, the ages of these units correspond in time with marine isotope stages [MIS] 4, 3, and 2. Sea level was significantly lower than present during all three time periods. Reconstruction of insular paleogeography indicates that large areas to the north and northwest of the islands would have been exposed at these times, providing a ready source of carbonate-rich skeletal sands. These findings differ from a previously held concept that carbonate aeolianites are dominantly an interglacial phenomenon forming during high stands of sea. In contrast, our results are consistent with the findings of other investigators of the past decade who have reported evidence of glacial-age and interstadial-age aeolianites on coastlines of Australia and South Africa. They are also consistent with observations made by Darwin regarding the origin of aeolianites on the island of St. Helena, in the South Atlantic Ocean, more than a century and a half ago.
... On stable continental shelves, palaeoshorelines record the position at which sea level persisted for periods long enough for coastal processes to form these structures (e.g. Harris et al., 2005;Brooke et al., 2010a;Cawthra et al., 2014; Table 1). Where preserved, these structures capture a valuable record of environmental change and can inform our understanding of modern shelf ecosystems, particularly the distribution of seabed features that provide important habitat for benthic biological communities (Banks et al., 2008;Nichol et al., 2012;Brooke et al., 2012a). ...
... Middle shelf High energy, micro tidal, carbonate Brooke et al., 2010aBrooke et al., , 2014Nicholas et al., 2014 Carnarvon Shelf, central Western Australia Field of mounds, 2-5 m relief, and ridges, up to 16 m relief and 1.5 km long,~shore normal (remnants of large parabolic dunes). ...
... Hence, depositional palaeoshoreline structures are likely to differ in morphology from their modern counterparts on any given coast. Further, the degree of preservation of these relict features will also vary depending on the intensity of coastal erosional processes during subaerial exposure and marine transgressions, and the volume and degree of resistance to erosion of the features (Bateman et al., 2004(Bateman et al., , 2011Cawthra et al., 2014;Nichol and Brooke, 2011;Brooke et al., 2010aBrooke et al., , 2014. ...
Palaeoshorelines that lie submerged on stable continental shelves are relict coastal depositional and erosional structures formed during periods of lower sea level. An analysis of the well-dated Late Quaternary (0–128 ka) sea-level record indicates that the most persistent (modal) lower sea levels were at 30 – 40m below present, which occurred between 97 and 116 ka and at approximately 85 ka and 10 ka. A secondary modal position was at 70–90m that occurred mostly during a period of fluctuating sea level between 30 and 60 ka, as well as at around 87 ka (70 – 80m only) and 12−15 ka. For the tectonically stable Australian continental shelf, we show that a range of shorelines formed at each of these sea level modal positions and their morphology and degree of preservation depends on composition (carbonate vs siliciclastic) and oceanographic setting (wave, tide and wind energy). These ancient coasts record a range of oceanographic and geological regimes that existed during relatively long periods of lower sea level and provide a guide to the general depth zones in which similar features likely occur on other shelves globally. Australian palaeoshorelines represent distinctive benthic habitats that strongly influence the distribution of biodiversity across the shelf. Accurate mapping of these features provides a robust geospatial framework for investigations of marine species distributions and environmental change monitoring. These data also enable the better targeting of relict coastal areas that potentially include sand resources and sites of human occupation during periods of lower sea level.
... Morphologically, the drowned valley systems strongly resemble the modern estuarine complexes present along the modern Kimberley coastline and, further, some of the submarine bathymetric ridges are morphologically similar to the beach-ridge coastal plains of northeastern Australia (Semeniuk 2011; Short 2011). The stable tectonic setting means that these submerged features remain at depths that closely match the global sea-level record (Brooke et al. 2010;Nichol & Brooke 2011). Therefore, the area not only provides a unique record of past sea-level change but also potentially of early human coastal resource use in this northern corridor of Australia (see Veth et al. 2014;Ward et al. 2013;2014b;2015). ...
... This palaeogeography is sufficient to warrant the area to be considered of significant geoheritage value (Bruno et al. 2014) and worthy of dedicated marine archaeological investigation. High-resolution LIDAR and 3D geophysical survey imagery is continuing to reveal drowned fossil dune ridges and palaeoshoreline sequences along much of the WA continental shelf, including near Perth (Brooke et al. 2010;Semeniuk & Searle 1987;Stul et al. 2015), at Ningaloo Reef (Collins et al. 2003;Nichol et al. 2012;WAMSI 2008) and off Port Hedland (BHP Billiton 2008). The clear implication is that there is the potential for pre-European landscapes and marine archaeological sites to be preserved over many hundreds and possibly thousands of kilometres of the WA continental shelf. ...
This paper examines the prehistoric marine archaeological potential of relict shorelines off James Price Point, northern Western Australia. In addition to previously registered midden and intertidal fish-trap sites, archaeological excavation at James Price Point has provided evidence of coastal exploitation from at least 5 ky BP. In the adjacent marine environment are well-preserved drowned shoreline sediments, that form at least two series of north - south trending linear features with relief of up to 5 m of more above the surrounding seabed, at elevations of - 15 m and - 8 m respectively, which may date to ~ 9 ky BP and ~ 6 ky BP respectively. The submerged shorelines are associated with four main depositional environments, of which, ‘lagoon infill’ and ‘fossil intertidal flats’ have the highest preservation potential and highest archaeological potential. This palaeogeography has significant geoheritage value and systematic investigation of these features is likely to contribute to our understanding of early maritime adaptation and resource use in this region.
... RS and GIS routines can be easily replicated and treated as (submarine) landform assessment protocols, which if affordable enough, are especially important in developing countries natural resource management (Bocco et al., 2000). Especially ecosystembased management of the marine environment or benthic habitats characterization require a seabed landform assessment, which is achievable only through remote sensing application (Brooke et al., 2010). ...
... Source:Nichol et al., 2010. Vollmer et al., 2015.In Western Australia (Swan coastal plain and Rottnest Shelf), a merged topographic-bathymetric dataset obtained by LADS MKII enabled geomorphic features on the shelf and coastal plain to be displayed together (see figure 4), allowing sedimentary dynamics and the influence of past changes in sea level to be described(Brooke et al., 2010). ...
This brief essay deals with some general issues related to geomorphological mapping with a special
focus on the remote sensing technologies and GIS methodologies adopted for its submarine
application. Finally, a little section will provide insights and examples regarding Australian
organisations and their major geomorphological mapping studies.
