Geographe Bay map showing simplified surface geology (redrawn after Playford et al. 1976), localities (red labels) and bodies of water (black labels). 1 Cape Naturaliste, 2 Jingarmup Creek, 3 Dunsborough, 4 Toby Inlet, 5 Toby drain, 6 Quindalup, 7 Broadwater-New River, 8 Vasse-Diversion drain, 9 Busselton and Busselton Jetty, 10 Vasse River, 11 Port Geographe Marina, 12 Vasse-Wonnerup Estuary, 13 Sabina River, 14 Abba River, 15 Lundlow River, 16 Capel River, 17 Mile Brook diversion, 18 Point Casuarina (Bunbury). A1, A2 and A3 are the seismic survey locations. The geophysical survey track plot is also marked (in pink). Hydrography: Linear (Hierarchy; Department of Water DOW-029; 29-10-2008 12:18:04) from Shared Location Information Platform (SLIP; WMS Server: https://www2.landgate.wa.gov.au/ows/ wmspublic?; Service Name: SLIP Public Web Map Service (ISO 19115 Categories). Simplified bathymetric contours are shown (source: Department of Transport).

Contexts in source publication

Context 1

... for the inferred chronostratigraphy of the survey area, are the geotechnical, sedimentological and palynological data obtained through the 'Quindalup borehole line project' (Wharton 1981(Wharton , 1982 and the 'Busselton shallow-drilling project', ( Hirschberg 1988Hirschberg , 1989) on the Swan Coastal Plain between Dunsborough and Capel ( Fig. 1), as part of an assessment of the groundwater resources of the Perth Basin. Although the majority of these studies were investigating groundwater aquifers, the findings derived by collecting terrestrial borehole sediment can be extended to the nearshore marine area, due to proximity of the boreholes to the ...

Context 2

... Bay is a 90 km long, J-shaped bay with a west-northwest aspect in the north and north-west through to north-east in the south (Fig. 1). The nearshore bathymetry is relatively simple with a shallow-dipping seabed reaching 30 m depth about 15 km from the coast. However, the south-westernmost section between Dunsborough and Cape Naturaliste is characterised by a steeper bathymetric gradient with water depths reaching 40 m within 1 km of the coast (Fig. ...

Context 3

... to north-east in the south (Fig. 1). The nearshore bathymetry is relatively simple with a shallow-dipping seabed reaching 30 m depth about 15 km from the coast. However, the south-westernmost section between Dunsborough and Cape Naturaliste is characterised by a steeper bathymetric gradient with water depths reaching 40 m within 1 km of the coast (Fig. ...

Context 4

... region is characterised by a Mediterranean climate, warm and dry between November and March (summer) and cool and wet in winter (Bureau of Meteorology -Australia 2011). There is only one permanent river (Capel River; Fig. 1, no. 16) that discharges directly into the ocean (mean annual flow of 39.9 Gigalitres (Department of Water 2008), the other waterways are ephemeral or seasonal and flow Playford et al. 1976), localities (red labels) and bodies of water (black labels). 1 Cape Naturaliste, 2 Jingarmup Creek, 3 Dunsborough, 4 Toby Inlet, 5 Toby drain, 6 ...

Context 5

... Shoreline deposits (possibly Middle Pleistocene Yoganup Formation), the Bassendean, Spearwood and Quindalup Dune Systems, respectively the MiddleUpper Pleistocene Bassendean Sand, eolian limestone and yellow sand of Tamala Limestone; and Holocene marine and eolian parabolic dunes and the Safety Bay Sand ( Playford et al. 1976;Commander 2003; Fig. ...

Context 6

... 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). A map of the main seafloor ...

Context 7

... morphological information was used to determine which areas within the bay to carry out the following seismic survey. Three distinct areas (A1-3; Fig. 1) were selected for detailed seismic investigation and sediment sampling: (1) A1 in the westernmost portion of the investigation area is characterised by a high concentration of sandbars, oblique to the shoreline; (2) A2, 6 km seaward from Busselton Jetty, has numerous deep-water (~20 m) ridges and palaeochannels; and (3) A3, in front ...

Context 8

... total of 71 km of high-resolution reflection seismic profiles were acquired between the mouths of Buayanup drain and Capel River (A1, A2 and A3, Fig. 1). The main track orientations were parallel and perpendicular to the coastline, to capture most elements of the seafloor morphology. In A1, the seismic survey covered 16 km, mainly oriented north-northeasterly to southsouthwesterly, in water depths of 5-10 m. A total of 15 km of seismic profiles were collected within A2, in relatively ...

Context 9

... sandbars and associated swales are near-continuous linear features that extend obliquely (at an acute angle to the shoreline of 15-30°) from nearshore, up to ~6 km seaward (between Geographe and West Busselton), to a water depth of 10 m. They mainly lie in the south-western portion of the bay, with the easternmost sandbar lying in front of the northern tip of Vasse-Wonnerup Estuary (location 12 in Figs 1, 3). The distance between successive sandbar crests increases to the north-east, ranging from about 250 m to more than 1.5 km. ...

Context 10

... black cross symbols r e p r e s e n t s t a t i o n s w h e r e sampling was unsuccessful due to the hard substrate. The green line marks the location of the seismic profile in Figure 12. SOL: Start of Line; EOL: End of Line. the propagation of the signal, causing scattering and consequent deterioration of the quality in the acquired profiles. ...

Context 11

... following chronostratigraphic interpretation is based on the findings of previous investigations carried out by the Geological Survey of Western Australia (Wharton 1981(Wharton , 1982Hirschberg 1988Hirschberg , 1989Deeney 1989). During these studies, which aimed to define the lateral and vertical extent of the local aquifer systems, three clusters of boreholes were drilled near the shoreline adjacent to Area 1 (just west of Busselton, Figs 1, 9). The bore completion reports (Hirschberg 1988) showed that the shallow stratigraphy, up to 50 m below the Australian Height Datum (AHD) includes three successive units): (1) the Lower Cretaceous Leederville Formation (Unit B, basement); (2) the Pleistocene Tamala Limestone (up to 15 m thick); and (3) Holocene deposits (maximum thickness of 10 m; Fig. 9). ...

Context 12

... Tamala Limestone forms a coastal strip, roughly parallel to the present shoreline, extending up to 10 km inland and 30 km offshore (inner shelf, Brooke et al. 2010) and stretches along the state's coast for more than 1000 km, from the South West to Shark Bay in the north (Fig. 1, right bottom corner). The formation represents a series of shoreline deposits and associated eolianite buildups (cemented dunes), composed of coastal carbonate sediment and quartzose sand (Brooke et al. 2010), deposited during Pleistocene marine transgressive events (Brooke et al. ...

Context 13

... the timing of marine inundations. For instance, Baker et al. (2005) dated relict formations of inter-tidal serpulid tubeworms (vertical resolution as sea-level indicators: ±25 cm, following Baker & Haworth 1997;Baker & Haworth 2000 andBaker et al. 2001) from 21 locations along southern Western Australia, from Rottnest Island to Esperance (Fig. 1). Their research demonstrated that sea level peaked about 2.0 m above present between 6600 and 6800 years Before Present (BP), followed by an uneven fall to the present. Notably, a similar timing and elevation of the peak Holocene sea level was identified by Jahnert & Collins (2013) and Bufarale & Collins (2015) in Shark Bay. According ...

Context 14

... Geographe Bay, the oblique sandbars, first described by Paul & Searle (1978), are all subparallel (Fig. 10). Superimposing the sandbar map distribution (from Fig. 10) to the mean wave direction chart (Fig. 11), the interaction between these elements is highlighted, with the sandbars positioned perpendicular to the mean wave direction. The mean wave direction chart shows how the south-westerly storm waves are refracted around Cape Naturaliste ...

Context 15

... Geographe Bay, the oblique sandbars, first described by Paul & Searle (1978), are all subparallel (Fig. 10). Superimposing the sandbar map distribution (from Fig. 10) to the mean wave direction chart (Fig. 11), the interaction between these elements is highlighted, with the sandbars positioned perpendicular to the mean wave direction. The mean wave direction chart shows how the south-westerly storm waves are refracted around Cape Naturaliste toward Geographe Bay coast ), clearly playing a ...

Context 16

... Geographe Bay, the oblique sandbars, first described by Paul & Searle (1978), are all subparallel (Fig. 10). Superimposing the sandbar map distribution (from Fig. 10) to the mean wave direction chart (Fig. 11), the interaction between these elements is highlighted, with the sandbars positioned perpendicular to the mean wave direction. The mean wave direction chart shows how the south-westerly storm waves are refracted around Cape Naturaliste toward Geographe Bay coast ), clearly playing a significant role in mobilising the sediment and ...

Context 17

... the study area, several surficial and buried palaeochannels have been detected through highresolution bathymetric and seismic datasets. Buried palaeochannels are mainly found in A1, where six incisions can be depicted in the seismic profiles (Fig. 10). In A2 and A3, four and three main buried palaeochannels can be recognised, respectively. In area A2, the westernmost buried palaeochannels appear to be the prolongation of channel 1 and 2 (Fig. 10) seaward. In Area 3, a deep incision is clearly observed in the seismic profiles close to the shoreline (Fig. 2). The palaeochannel is ...

Context 18

... bathymetric and seismic datasets. Buried palaeochannels are mainly found in A1, where six incisions can be depicted in the seismic profiles (Fig. 10). In A2 and A3, four and three main buried palaeochannels can be recognised, respectively. In area A2, the westernmost buried palaeochannels appear to be the prolongation of channel 1 and 2 (Fig. 10) seaward. In Area 3, a deep incision is clearly observed in the seismic profiles close to the shoreline (Fig. 2). The palaeochannel is directly in line with the modern mouth of the Capel River, evidence that an ancient Capel River was active also in the past. At present, the incision is ~5 m deep, but considering that erosion of the ...

Context 19

... is likely to have happened, this channel and related palaeoriver might have been more significant, in terms of dimensions, discharge and flow than the modern one. The buried and surficial palaeochannels typically follow the same course, indicating that the pre-existing topography may have shaped and influenced successive morphological features (Fig. 12). Figure 8) showing an underlying seafloor palaeochannel that is the surficial expression of a buried incision. The vertical axis corresponds to the depth below sea level (BSL) and the scale is in metres. The sound velocity in the sediments is equivalent to ~2000 m/s. Surficial incisions, recognisable in the high-resolution bathymetric ...

Context 20

... to different Holocene thicknesses between the north-eastern A3 and the south-western A1. In the latter, where the Holocene unit is well-developed and a large amount of sediment is trapped along the sandbars, the palaeochannels have been infilled and covered up, and hence not recognisable within the bathymetric data, only in seismic profiles (Fig. 13). In A3, on the other hand, strong coastal currents (Fahrner & Pattiaratchi 1994) and the lack of seagrass meadows (McMahon et al. 1997;Oldham et al. 2010) have limited the deposition of sediment that instead has been transported and deposited farther south, leaving the surficial incisions more evident in the bathymetric ...

Context 21

... central-western Geographe Bay (near study area A1), similar to along the coasts of North Carolina and Virginia (U.S.A.; Browder & McNinch 2006) and Paraná inner shelf (southern Brazil; Oliveira 2015), buried palaeochannels and oblique sandbars are found adjacent (Fig. 13). However, unlike coastal U.S.A. and Brazil, where palaeochannels have been argued to influence the development of shore-oblique sandbars (McNinch 2004), in Geographe Bay this relationship is not significant as hydrodynamic conditions (waves and currents) are the main process involved in the formation of bottom geomorphology (Paul & ...

Context 22

... to the onshore Swan Coastal Plain, where subaerial coastal dune ridges become progressively younger from east to west (Commander 2003), the submerged ridges also young in the same direction, recording Late Pleistocene relatively high sea level stages. The schematic cross sections illustrating the Late Quaternary geomorphological evolution (Fig. 14) show how shallowwater ridges in the south (area A1 in Fig. 1) might have been eroded completely or covered by Holocene sediments, whereas they are preserved in the north (area A3 in Fig. 1).The shallow-water ridges in the south (area A1) might have been eroded completely or covered by Holocene sediments. The shallow-water ridges were ...

Context 23

... dune ridges become progressively younger from east to west (Commander 2003), the submerged ridges also young in the same direction, recording Late Pleistocene relatively high sea level stages. The schematic cross sections illustrating the Late Quaternary geomorphological evolution (Fig. 14) show how shallowwater ridges in the south (area A1 in Fig. 1) might have been eroded completely or covered by Holocene sediments, whereas they are preserved in the north (area A3 in Fig. 1).The shallow-water ridges in the south (area A1) might have been eroded completely or covered by Holocene sediments. The shallow-water ridges were the first ridge complex to form. At the termination of MIS 5e, ...

Context 24

... recording Late Pleistocene relatively high sea level stages. The schematic cross sections illustrating the Late Quaternary geomorphological evolution (Fig. 14) show how shallowwater ridges in the south (area A1 in Fig. 1) might have been eroded completely or covered by Holocene sediments, whereas they are preserved in the north (area A3 in Fig. 1).The shallow-water ridges in the south (area A1) might have been eroded completely or covered by Holocene sediments. The shallow-water ridges were the first ridge complex to form. At the termination of MIS 5e, when the sea level was about 8 to 10 m lower than the present (Chappell et al. 1996), these barriers started their development, ...

Context 25

... the south (area A1) might have been eroded completely or covered by Holocene sediments. The shallow-water ridges were the first ridge complex to form. At the termination of MIS 5e, when the sea level was about 8 to 10 m lower than the present (Chappell et al. 1996), these barriers started their development, close to the innermost palaeo shoreline (Fig. 14, ~120 ka). When the sea level further dropped, stranding these features, cementation commenced. Similarly, the second ridge complex (deep-water ridges) established its shape in an analogous manner, when the sea level was 20-30 m below present (Chappell et al. 1996;Creveling et al. 2017; Fig. 14, ~100 ky). Until ~10 ky BP, most of the inner shelf ...

Context 26

... close to the innermost palaeo shoreline (Fig. 14, ~120 ka). When the sea level further dropped, stranding these features, cementation commenced. Similarly, the second ridge complex (deep-water ridges) established its shape in an analogous manner, when the sea level was 20-30 m below present (Chappell et al. 1996;Creveling et al. 2017; Fig. 14, ~100 ky). Until ~10 ky BP, most of the inner shelf was exposed, favouring the cementation of the ridges. When the sea level inundated the shelf (early Holocene), erosion took place, leaving the lithified ridges asymmetric, with a flat top (Fig. 14, ...

Context 27

... manner, when the sea level was 20-30 m below present (Chappell et al. 1996;Creveling et al. 2017; Fig. 14, ~100 ky). Until ~10 ky BP, most of the inner shelf was exposed, favouring the cementation of the ridges. When the sea level inundated the shelf (early Holocene), erosion took place, leaving the lithified ridges asymmetric, with a flat top (Fig. 14, ...