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  • Multibeam bathymetry gridded at 20m resolution and projected to WGS84 UTM zone 50S from the North Perth Survey (GA reference GA-0332).

  • The Marine Survey Multibeam Bathymetry Web Map Service contains the highest-resolution multibeam bathymetry grids available for download on Geoscience Australia's website. These bathymetry grids were collected over numerous multibeam survey programs conducted in Australian mainland and Antarctic waters by both Geoscience Australia and our collaborators. Layers are grouped by survey or region and where available include both the Geoscience Australia and vessel survey identification numbers that contributed to the bathymetry grids. Bathymetry grids have been rendered over a rainbow colour-ramp with minimum and maximum depth values unique for each survey. These values are specified in each survey's layer description. The resolution of each bathymetry grid is also specified in each survey's layer description

  • This report presents the results of seabed mapping and habitat classification surveys completed in Darwin Harbour during 2011 and 2013 as part of the Northern Territory Government's marine habitat mapping program. This research aims to provide baseline data on the existing marine habitats and characteristics of the Darwin Harbour region. It is a collaboration between Geoscience Australia (GA), the Australian Institute of Marine Science (AIMS), the Department of Land Resource Management (DLRM) and the Darwin Port Corporation. Key objectives are to: - Produce detailed maps of the bathymetry and derived parameters such as slope and rugosity, - Classify the seabed into areas of hard and soft substrate, and, - Produce seabed habitat maps (or seascapes). Data collection was completed in two stages comprising a multibeam survey, undertaken on the MV Matthew Flinders in 2011 by DLRMs predecessor, the Department of Natural Resources, Environment, the Arts and Sport (NRETAS), GA, AIMS and the Darwin Port Corporation; and, a seabed sampling survey undertaken in 2013 on the MV John Hickman, by DLRM and GA. Data acquired from the surveys included continuous high-resolution multibeam sonar bathymetry and acoustic backscatter, video and still camera observations of seabed habitats and biological communities, and physical samples of seabed sediments. Key outcomes from the surveys include: 1. Improved understanding of the seabed of Darwin Harbour. The main seabed geomorphic features identified in Darwin Harbour include banks, ridges, plains and scarps, and a deep central channel that divides into smaller and shallower channels. Acoustically hard substrates are found mostly on banks and are associated with rocky reef and sponge gardens, and are often overlain by a thin veneer of sandy sediment. In contrast, plains and channels are characterised by acoustically soft substrates and are associated with fine sediments (mud and sand). 2. Classification of physical seabed properties to produce a Seascape Map for Darwin Harbour. Six seascape classes (potential habitats) were derived using an Iterative Self Organising (ISO) unsupervised classification scheme. These six classes are related to statistically unique combinations of seabed substrate, relief, bedform and presence of sediment veneer (quite often inferred from presence of epibenthic biota). The results presented in this report demonstrate the utility of multibeam acoustic data to broadly and objectively characterise the seabed to describe the spatial distribution of key benthic habitats. This is particularly important technique in high-turbidity settings such as Darwin Harbour where the application of satellite and aerial remote sensing techniques can be limited. The results of this study will be used for the planning and analysis of data from upcoming benthic biodiversity studies as they: - Provide robust near-continuous physical variables that can be used to predictive modelling of biodiversity; - Provide high-resolution coverage of near-continuous variables that describe the key physical characteristic of the seabed of the harbour, and; - Enhance survey sample design by providing indicative locations of likely similar biology communities.

  • Geoscience Australia carried out a marine survey on Carnarvon shelf (WA) in 2008 (SOL4769) to map seabed bathymetry and characterise benthic environments through colocated sampling of surface sediments and infauna, observation of benthic habitats using underwater towed video and stills photography, and measurement of ocean tides and wavegenerated currents. Data and samples were acquired using the Australian Institute of Marine Science (AIMS) Research Vessel Solander. Bathymetric mapping, sampling and video transects were completed in three survey areas that extended seaward from Ningaloo Reef to the shelf edge, including: Mandu Creek (80 sq km); Point Cloates (281 sq km), and; Gnaraloo (321 sq km). Additional bathymetric mapping (but no sampling or video) was completed between Mandu creek and Point Cloates, covering 277 sq km and north of Mandu Creek, covering 79 sq km. Two oceanographic moorings were deployed in the Point Cloates survey area. The survey also mapped and sampled an area to the northeast of the Muiron Islands covering 52 sq km. The dataset contains 6 bathymetry grids of the Carnarvon Shelf study area produced from the processed EM3002 bathymetry data using the CARIS HIPS and SIPS software. Please see the metadata for detailed information.<p><p>This dataset is not to be used for navigational purposes.

  • The Murray Canyons are a group of deeply-incised submarine canyons on a steep 400-km section of the continental slope off Kangaroo Island, South Australia. Some of the canyons are amongst the largest on Earth. The canyons, some 80 km long, descend from the shelf edge to abyssal plain 5200 m deep. Sprigg Canyon, the deepest and one of the largest, has walls 2 km high. The thalwegs of the larger canyons are concave in profile, steepest on the upper continental slope (15?-30?), with about 4?gradient on the mid slope, then level out on the lower slope to merge with the 1? continental rise. Between canyons, the continental slope is slightly convex to linear with a gradient of about 5?-6?. Canyon walls commonly slope at 15?-22?. The passive continental margin narrows to 65-km at the Murray Canyons and links the Bight and Otway Basins. WNW-trending Jurassic-Cretaceous rift structures control the irregular shape of the central canyons. At the western end, large box canyons 1 km deep are incised into thick sediments of the Ceduna Sub-basin. Formed by headscarp erosion, some of these canyons have coalesced by canyon capture. The upper parts of most canyons are cut into Cretaceous sediments and in some places are floored by basement rocks. Large holes, spaced about 5 km apart and up to several hundred metres deep, along the outlet channels of the larger and steeper canyons were probably gouged by turbidity currents resulting from major slope failures at the shelf edge. Quaternary turbidites were deposited on the abyssal plain more than 100 km from the foot of slope. Canyon down-cutting was episodic since the latest Cretaceous, with peak activity since the Oligocene due to strong glacioeustatic fluctations and cycles, with canyon development occurring during lowstands and early transgressions when sediment input at the shelf edge was usually highest. The timing of canyon development is linked to major unconformities within adjacent basins, with down-cutting events recorded or inferred during early Paleocene, Middle Eocene, Early Oligocene, Oligocene/Miocene transition (~24 Ma), mid Miocene (~14 Ma) and latest Miocene-Pleistocene. The early phases involved only siliciclastic sediments, while post-early Eocene canyon cutting was dominated by biogenic carbonates generated on the shelf and upper continental slope. The Murray River dumped its sediment load directly into Sprigg Canyon during extreme lowstands of the Late Pleistocene when the Lacepede Shelf was dry land.

  • Surveying of nearshore areas in the Vestfold Hills using high resolution multibeam swath bathymetry provides both a detailed digital bathymetric model and information on sediment acoustic backscatter. Combined with underwater video transects and sediment sampling, these data can be used to identify and map geomorphic units. Six geomorphic units identified in the survey region include: Rocky outcrops, sediment-floored basins, pediments, steep-sided valleys, scarps and sheltered embayments. In addition to geomorphic units, the data reveal sedimentary structures that provide insights into sediment transport and erosion in the area. Ice keel pits and scours are common while seafloor channels, scour depressions and sand ribbons indicate transport and deposition by wind-driven currents and oceanographic circulation. Gullies and sediment lobes on steep slopes indicate mass movement of sediment. The sheltered embayments preserve a mantle of boulder sand probably deposited by cold-based glaciers. Automated techniques utilizing the bathymetric grid and backscatter to map landforms are useful in defining reproducible boundaries between geomorphic units but cannot easily be adapted to accurately classify the variations in sea floor texture and structure imaged by these data.

  • Flythrough of the Austrlalian Margin (not including the northern margin) showing detail of the Exmouth Plateau, Perth Canyon, Murray Canyons, NSW Slope and Great Barrier Reef. Gridded bathymetry data shown in this product was sourced from GA and James Cook University.

  • This tile contains all multibeam data held by Geoscience Australia on August 2012 within the specified area. The data has been gridded to 50m resolution. Some deeper data has also been interpolated within the mapped area. The image provided can be viewed on the free software CARIS Easyview, available from the CARIS website: www.caris.com under Free Downloads.

  • This tile contains all multibeam data held by Geoscience Australia on August 2012 within the specified area. The data has been gridded to 50m resolution. Some deeper data has also been interpolated within the mapped area. The image provided can be viewed on the free software CARIS Easyview, available from the CARIS website: www.caris.com under Free Downloads.

  • This tile contains all multibeam data held by Geoscience Australia on August 2012 within the specified area. The data has been gridded to 50m resolution. Some deeper data has also been interpolated within the mapped area. The image provided can be viewed on the free software CARIS Easyview, available from the CARIS website: www.caris.com under Free Downloads.