Articoli di riviste sul tema "Geomorphology South Australia"

This article provides a review of the study and geomorphology of Australia's fluvial systems by offering comment on the development, concerns and future of the subject. Trends in the history of fluvial landform studies in Australia are traced from the observations and comments of the early explorers and visiting scientists through to the emergence and growth of fluvial geomorphology as a study discipline. Subsequent development of the idea of a distinctive geomorphology of Australian fluvial systems that often contrast with Anglo-American observations is outlined and illustrated with particular reference to fluvial studies in south-east Australia. Key features of the Australian setting include low long-term denudation rates, the absence of extensive Quaternary glaciation and the predominance of low gradient fluvial systems over much of the continent. Some of the most important themes in contemporary Australian fluvial research are discussed and include long-term landscape evolution, thresholds and riverine response to secular trends in climate, Quaternary environmental change, arid-environment systems, bedrock channels and applied approaches to study. Consideration is also given to present deficiencies in research and to future priorities. Particular attention is focused on the need firstly to collect additional process data, secondly to shift the bias in research away from south-east Australia, and thirdly to develop links between fluvial process and alluvial stratigraphy/chronology. It is concluded that, given the variety of hydrogeomorphological environments in Australia and the diversity of approaches to study, ongoing research will provide further indications of the unusual nature of many of the continent's fluvial systems.

This study examines landscape rehabilitation treatments installed 20–40 years ago in the Western Catchment of NSW. Treatment outcomes were assessed using geomorphic criteria, because geomorphic processes are fundamental to ecological permanence. Contour furrowing creates artificial runoff-runon sets which intercept runoff (resistance to flow by windrows microrelief and surface roughness) and promote infiltration (artificial permeability by ripping). As originally conceived, after windrows subside, flow resistance would be afforded by surface roughness under belts of vegetation. This study shows that rehabilitation treatments have a more complex relationship with the landscape than this would suggest, and that the final effect of the treatment depends on the geomorphic processes natural to the site. Treatment design should therefore be site-specific. The relevant aspects of treatment design are site location, runoff : runon ratio (expressed as furrow spacing and furrow length), furrow placement, and post-treatment management. Some long-term successes are documented. In ironstone ridge country affected by impermeable hard-setting soils, furrowing creates artificial permeability, allowing plant germination; plant material in the soil reverses hard-setting and establishes self-sustaining permeability. In stony gilgai country furrowing through vegetated patches can aid in re-establishing vegetation, but furrowing through stony runoff patches only diminishes, rather than improves, landscape function. Other landscape types will have different key attributes. In all cases, selection of appropriate sites for rehabilitation treatment is of primary importance. The 1990s NSW Soil Conservation Service best-practice included a specialised furrower, surveying techniques for accurate furrow placement along the contour, staggered gaps along each furrow line to reduce risks of gullying by windrow breakthrough, and post-treatment management of total grazing pressure. New guidelines for treatment design developed from this study include determining for each site the optimum runoff:runon ratio (which varies according to climate, gradient, vegetation, and regolith), and matching furrow spacing and furrow/gap length to local runoff:runon ratios. In stony gilgai country, furrow placement should be along the contour but within non-stony patches; elsewhere, placement should be rigorously along the contour. In ironstone ridge country, a greater runoff:runon ratio, commensurate with the area’s apparently larger patch scale, can be achieved by having more gap than furrow along each furrow line. No single rehabilitation technique will fit all landscape types, and these guidelines will ideally be developed further with investigation of other landscapes.

The received wisdom was and is that landscapes cannot be more than a few millions of years old. Nevertheless, consideration of local geology and age of sediments in adjacent basins convinced Paul S. Hossfeld that the summit surface of low relief preserved on the northern Mount Lofty Ranges of South Australia resulted from long-continued planation and that it is of Cretaceous age; that is, some 70 million years old. Hossfeld's apparently intuitive suggestion that very old landscapes exist, recorded in his graduate thesis but not further pursued by him, is the earliest known statement of this idea.

Abstract. Here we present the results of a multi-proxy investigation – integrating geomorphology, ground-penetrating radar, and luminescence dating – of a high-elevation lunette and beach berm in northern New South Wales, eastern Australia. The lunette occurs on the eastern shore of Little Llangothlin Lagoon and provides evidence for a lake high stand combined with persistent westerly winds at the Last Glacial Maximum (LGM – centring on 21.5 ka) and during the early Holocene (ca. 9 and 6 ka). The reconstructed atmospheric circulation is similar to the present-day conditions, and we infer no significant changes in circulation at those times, as compared to the present day. Our results suggest that the Southern Hemisphere westerlies were minimally displaced in this sector of Australasia during the latter part of the last ice age. Our observations also support evidence for a more positive water balance at the LGM and early Holocene in this part of the Australian sub-tropics.

The invasion of northern Australia by the poisonous cane toad is well recognised, as is its devastating impacts on numerous local native species. However, there is little recognition that the toads are spreading into south-western Queensland. Utilising local knowledge, a limited survey was undertaken within the Cooper Creek catchment to locate the invasion front. Dispersal during 2010–11 floods has established cane toads as far south as Jundah. Integrating this information with landform mapping indicates that cane toad invasion can continue south-west down the Cooper Creek. Though arid, Cooper Creek’s geomorphology renders it partially independent of local climate, and permanent and semipermanent waterholes (including RAMSAR-listed wetlands) are found downstream from Windorah and into the Strzelecki Desert. Natural landforms provide potential daytime shelter and breeding sites, and additional suitable habitat created by human activity is also widespread. Even unsuccessful attempts at breeding may be detrimental to regional ecology, especially fish populations, at critical stages of their boom/bust cycle. We conclude that there is no reason why cane toads cannot penetrate further down the Cooper Creek, threatening wetlands in north-eastern South Australia. Published models of cane toad expansion, which conclude that north-eastern South Australia is too dry for cane toad populations to establish, are based on climatic parameters that significantly under-represent true habitat availability.

Phylogeographic patterns in the cp genome of Eucalyptus marginata Don ex Sm., a species common in the mesic region of south-western Australia, were investigated by using RFLP analysis. The chloroplast diversity was structured into two geographically distinct lineages and nested clade analysis inferred historical fragmentation as the major influence on the phylogeographic pattern. The lineages were separated along the geomorphological boundary of the Darling Scarp, which separates the Coastal Plain from the Darling Plateau. The divergence between the lineages is consistent with uplifting of the Darling Plateau in the late Neogene. Further geographic structuring in haplotype distributions was evident in the forest lineage on the Darling Plateau, where one sublineage was present in the central forest region and another was restricted to the south-eastern region. The level of divergence between these sublineages was similar to that between divergent lineages that have been identified in comparative phylogeographic studies of cpDNA variation in three species widespread throughout south-western Australia. In these species, divergence was attributed to the influence of significant changes in climatic oscillations across the semi-arid region during the mid-Pleistocene. The divergence identified in this study indicates that the influence of climatic change was widespread throughout south-western Australia, including the mesic, higher-rainfall region.

The distribution and productivity of mangroves is directly affected by a wide range of climatic drivers, including temperature, frost, rainfall, evaporation and storm activity, which, in turn, influence a suite of secondary drivers, including changes in freshwater run-off and sediment supply, groundwater dynamics and inter-species competitiveness. The highest-latitude expression of mangroves globally is at Millers Landing, Victoria (38°45′S), and because the vigour and productivity of mangroves across much of Victoria is thought to be limited by low winter temperatures and the incidence and severity of frosts, it is likely that mangroves will be among the first plant communities to be affected by climate change in coastal south-eastern Australia. An increase in plant vigour is likely, but there are almost no historical data with which to compare current rates of primary production. An extension of mangroves to higher latitudes on the mainland is impossible because of the geomorphology of the land that lies further to the south. Small-scale changes in distribution, including the progressive encroachment of mangroves into coastal saltmarsh, are likely to be among the clearest indications of the response of mangroves to a warming climate. Increased effort into tracking changes in mangrove vigour, productivity and distribution is clearly warranted.

Recent erosion in arid regions of western NSW has exposed large areas that are scattered with stone artefacts manufactured by Aboriginal people in prehistory. These exposures offer an opportunity for archaeologists to study the artefacts abandoned by Aboriginal people through time and to compare those artefacts that accumulate in different parts of the landscape. To reconstruct the nature of prehistoric behaviour in the rangelands, two approaches are needed. First, the geomorphological context of the artefacts needs to be considered since exposure of the artefacts is a function of landscape history. Second, large areas (measured in thousands of square metres) and large numbers of artefacts need to be considered if patterns reflecting long-term abandonment behaviour by Aboriginal people are to be identified. This paper reports on the Western New South Wales Archaeological Program (WNSWAP) which was initiated in 1995 to study surface archaeology in the rangelands. Geomorphological studies are combined with artefact analysis using geographic information system software to investigate Aboriginal stone artefact scatters and associated features such as heat retainer hearths, in a landscape context. Results suggest that apparently random scatters of stone artefacts are in fact patterned in ways which inform on prehistoric Aboriginal settlement of the rangelands. Key words: Aboriginal stone artefacts; rangelands; landscape archaeology; geomorphology; GIs

The recognition and effective portrayal of floristic heterogeneity is a complex issue for land classification. This study in Toohey Forest, south-east Queensland, examines the effects of mapping scale and environmental variables on a floristically heterogeneous area. Current Version 4.1 regional ecosystem mapping at 1: 1 00 000 scale maps Toohey Forest as a single regional ecosystem unit "12.11.5", described as an "open forest complex with Corymbia citriodora, Eucalyptus siderophloia, E. major on metamorphics ± interbedded volcanics". Plant taxa data from 50, 20 x 20 m sites comprising 247 native vascular plant taxa were collected, along with data for 17 environmental variables and 10 species richness categories. A priori site groupings of 1 :12 500 scale vegetation mapping and a geomorphic classifications of the area were examined using cluster analysis (UPGMA, Bray-Curtis Metric, β = –0.1) and ordination (SSH MDS). Biplots of several variables (shrub species richness, total species richness, per cent rock cover, CEC, carbon and phosphorus) were significantly (P < 0.05) correlated with the ordination axes derived from each of the two strata levels and the total taxa, for both geomorphological and vegetation mapping. Several variables (shrub, vine, woody and introduced species richness, and carbon, nitrogen, phosphorus, pH and CEC) varied significantly (P < 0.05) across both geomorphic categories and 1:12 500 scale vegetation community mapping. The ongoing reduction in regional ecosystem mapping scale, centred on the use of fine-scale geomorphology mapping, is likely to improve the representation of floristic patterns in heterogeneous environments.

William Noel Benson was one of the most renowned geologists in Australia and New Zealand during the first half of the twentieth century. He studied geology at the Universities of Sydney and Cambridge and occupied the Chair of Geology at the University of Otago with great distinction for thirty-three years. His research work extended across the greater part of the geological spectrum and gained him world-wide recognition and a reputation as a scholar in the classical mode. His name is today most closely associated with his pioneering work on the composition, origin and tectonic setting of the mafic and ultramafic rocks of the Great Serpentine Belt of New South Wales, and with his unfinished study of the Tertiary volcanic rocks of the Dunedin district, in New Zealand. He also made important contributions in such diverse fields as palaeontology, geomorphology, engineering geology and medical geology. Benson was a highly respected teacher and a compassionate man with deep religious convictions.

AbstractAnalysis of the geomorphology, geology, and palynology of deposits in the King Valley permits the identification of four glaciations and two interglaciations and has led to a revision of the Pleistocene stratigraphy of the West Coast Range. The oldest late-Cenozoic deposits in the valley appear to predate glaciation, contain extinct pollen types, and are probably of late-Tertiary age. Overlying deposits of the Linda Glaciation show intense chemical weathering and have a reversed detrital remanent magnetization indicating deposition before 730,000 yr B.P. The highly weathered tills are conformably overlain by organic deposits of the Regency Interglaciation which show a transition from montane scrub rainforest to lowland temperate rainforest. Deposits formed during the later Moore Glaciation record advances of the King Glacier and glaciers from the West Coast Range. A pollen-bearing fluvial deposit records an interstade during this glaciation. On the basis of weathering rinds, amino acid dating, and palaeomagnetism the deposits are estimated to have formed between 730,000 and 390,000 yr B.P. The Moore Glaciation deposits are overlain by sediments of the Henty Glaciation which are believed to predate 130,000 yr B.P. These deposits record multiple advances of the King Glacier and the development of a large lake during an interstade. Deposits of the subsequent Pieman Interglaciation consist of organic fine sands and silts that record a lowland scrub rainforest. Deposits of the last (Margaret) glaciation are restricted to small areas in the northern part of the valley. Although the most recent ice advance culminated after 19,000 yr B.P., evidence of older deposits of the Margaret Glaciation suggests that an early last-glaciation ice advance may have occurred. When combined with earlier studies, the recent work in the King Valley has provided one of the more complete records of Pleistocene glaciation in the Southern Hemisphere. Comparison of the deposits with the record of glaciation in southern South America and Westland, New Zealand, suggests some similarities exist between pre-last-glaciation events and indicates that glacial events in Southern Hemisphere middle latitude areas were synchronous during the last glaciation.

This article explores nomadic site occupation as a form of planetary colonization involving both human and non-human agents. Conventional understandings of temporary occupation are often humancentric with little attention paid to the disruption of extant site ecologies and processes. The latter are particularly pressing concerns in nomadic settlements located in precarious landscapes. Taking the latter as its focus, this article engages the earth as an agent resisting its own colonization in the Australian-licensed squatter settlement known colloquially as Tin City. Located within the largest mobile sand dune structure in New South Wales, Tin City is an assemblage of several self-built fishing shacks accommodating a nomadic population. Its occupants engage in a daily battle against the shifting sands that threaten to subsume their temporary homes. Located in an area of significant indigenous heritage, the Tin City settlement has become a tourist attraction shrouded in local lore. Current discourses about it and its architectures generally focus on its unusual aesthetics, its contested sociopolitical histories and its ecology, with some discussion on the impacts of European colonization on the sand dune’s dynamic geomorphology. To concentrate on the latter, the article develops and deploys the posthumanist conceptualization of the earth posited by Iranian philosopher Reza Negarestani in his ficto-critical text Cyclonopedia: Complicity with Anonymous Materials. Negarestani ascribes the earth with sentient and agentic capacity, whilst the nomads who traverse its surfaces become the penultimate planetary colonizers. Tin City’s occupation thus becomes a story of colonization and resistance narrated by the earth itself, and a reminder that the production and consumption of architectural forms does not need to be confined to that which is conventionally human.

Organic carbon (OC) inputs, stores and processing underpin river functioning. We examined patterns in OC reservoirs (total organic carbon, TOC), suspended OC, drifting coarse particulate OC (drift OC), organic debris and the biomass of in-stream primary producers in five geographically proximate small rivers in south-eastern Australia during base-flow conditions. Despite differences in the extent of land-use conversion (native forest-to-pasture) and geomorphology among all sites, we found greater within-river than ‘within-land-use’ similarities in OC reservoirs. Our predictions regarding the relationships between distant v. proximate land-use and the OC reservoirs were mostly not confirmed. Riparian canopy cover was correlated with the mass of organic debris but not with other OC reservoirs. Our predictions regarding longitudinal patterns in rivers were also not confirmed. Rivers draining catchments with conservation land-use only did not show consistent patterns that were different from rivers draining a combination of conservation and grazing land. Variability in the extent of land converted to other uses was not necessarily associated with greater longitudinal variability in OC reservoirs. Our results suggest: (1) strong within-catchment controls of TOC concentration that are maintained despite a certain level of catchment impairment and (2) between-river differences in TOC at a local scale as great as continental scale differences.

In 2017, the New South Wales (NSW) Office of Environment and Heritage (OEH) initiated a state-wide mapping program, SeaBed NSW, which systematically acquires high-resolution (2–5 m cell size) multibeam echosounder (MBES) and marine LiDAR data along more than 2000 km of the subtropical-to-temperate southeast Australian continental shelf. This program considerably expands upon existing efforts by OEH to date, which have mapped approximately 15% of NSW waters with these technologies. The delivery of high volumes of new data, together with the vast repository of existing data, highlights the need for a standardised, automated approach to classify seabed data. Here we present a methodological approach with new procedures to semi-automate the classification of high-resolution bathymetry and intensity (backscatter and reflectivity) data into a suite of data products including classifications of seabed morphology (landforms) and composition (substrates, habitats, geomorphology). These methodologies are applied to two case study areas representing newer (Wollongong, NSW) and older (South Solitary Islands, NSW) MBES datasets to assess the transferability of classification techniques across input data of varied quality. The suite of seabed classifications produced by this study provide fundamental baseline data on seabed shape, complexity, and composition which will inform regional risk assessments and provide insights into biodiversity and geodiversity.

Abstract Southeastern Indonesia is located at a convergent triple junction of 3 plates : the Pacific (including the Caro-line and Philippines plates), the Australian and the Southeast Asian plates (fig. 1). The age of the different basins : the North Banda Sea (Sula Basin), the South Banda Sea (Wetar and Damar Basins) and the Weber Trough has been debated for a long time. Their great depth was a reason to interpret them as remnants of oceanic domains either of Indian or Pacific ocean affinities. It has now been demonstrated from geochronological studies that these basins have formed during the Neogene [Réhault et al., 1994 ; Honthaas et al., 1998]. The crust has been sampled only in the Sula Basin, where basalts or trachyandesites with back-arc geochemical signatures have been dredged. Their ages range from 11.4 ± 1.15 to 7.33 ± 0.18 Ma [Réhault et al., 1994 ; Honthaas et al., 1998]. The study of the magnetic anomaly pattern of these basins confirms this interpretation and defines an age between 12.5 and 7.15 Ma for the North Banda Basin and between 6.5 to 3.5 Ma for the South Banda Basin [Hinschberger et al., 2000 ; Hinschberger et al., 2001]. Furthermore, the existence of volcanic arcs linked to subducted slabs suggests that these basins resulted from back-arc spreading and subduction slab roll-back. Lastly, the Weber Trough which exceeds 7 300 m in depth and is one of the deepest non subduction basins in the world, remains enigmatic. A compilation of existing bathymetric data allows us to present a new bathymetric map of the region (fig. 2 and 3). A comparison with the previous published maps [Mammerickx et al., 1976 ; Bowin et al., 1982] shows numerous differences at a local scale. This is especially true for the Banda Ridges or in the Sula Basin where new tectonic directions are expressed. In the North Banda Basin, the Tampomas Ridge, which was striking NE-SW in the previous maps, is actually NW-SE parallel to the West Buru Fracture Zone and to the Hamilton Fault scarp (fig. 6). This NW-SE direction represents the initial direction of rifting and oceanic spreading. In this basin, only the southeastern rifted margin morphology is preserved along the Sinta Ridges. The basin is presently involved in an overall compressional motion and its buckled and fractured crust is subducted westwards beneath East Sulawesi (fig. 4a, 5 and 6). The northern border of the North Banda Basin is reactivated into sinistral transcurrent motion in the South Sula Fracture Zone continued into the Matano fault in Sulawesi. The South Banda Sea Basin is divided in two parts, the Wetar and Damar Basins with an eastward increase in depth. The Wetar and Damar Basins are separated by the NNW-SSE Gunung Api Ridge, characterized by volcanoes, a deep pull apart basin and active tectonics on its eastern flank (fig. 4b and 7). This ridge is interpreted as a large sinistral strike-slip fracture zone which continues across the Banda Ridges and bends towards NW south of Sinta Ridge. The Banda Ridges region, separating the North Banda Basin from the southern Banda Sea (fig. 5 and 7), is another place where many new morphological features are now documented. The Sinta Ridge to the north is separated from Buru island by the South Buru Basin which may constitute together with the West Buru Fracture Zone a large transcurrent lineament striking NW-SE. The central Rama Ridge is made of 2 narrow ridges striking NE-SW with an « en-echelon » pattern indicating sinistral strike slip comparable to the ENE-WSW strike-slip faulting evidenced by focal mechanisms in the northern border of the Damar Basin [Hinschberger, 2000]. Dredging of Triassic platform rocks and metamorphic basement on the Sinta and Rama Ridges suggests that they are fragments of a continental block [Silver et al., 1985 ; Villeneuve et al., 1994 ; Cornée et al., 1998]. The Banda Ridges are fringed to the south by a volcanic arc well expressed in the morphology : the Nieuwerkerk-Emperor of China and the Lucipara volcanic chains whose andesites and arc basalts have been dated between 8 and 3.45 Ma [Honthaas et al., 1998]. Eastern Indonesia deep oceanic basins are linked to the existence of 2 different subduction zones expressed by 2 different downgoing slabs and 2 volcanic arcs : the Banda arc and the Seram arc [Cardwell et Isacks, 1978 ; Milsom, 2001]. They correspond respectively to the termination of the Australian subduction and to the Bird’s head (Irian Jaya) subduction under Seram (fig. 5). Our bathymetric study helps to define the Seram volcanic arc which follows a trend parallel to the Seram Trench from Ambelau island southeast of Buru to the Banda Island (fig. 2 and 5). A new volcanic seamount discovered in the southeast of Buru (location of dredge 401 in figure 7) and a large volcano in the Pisang Ridge (location of dredge 403 in figure 7 and figure 8) have been surveyed with swath bathymetry. Both show a sub-aerial volcanic morphology and a further subsidence evidenced by the dredging of reefal limestones sampled at about 3000 m depth on their flank. We compare the mean basement depths corrected for sediment loading for the different basins (fig. 9). These depths are about 5 000 m in the Sula Basin, 4 800 m in the Wetar basin and 5 100 m in the Damar basin. These values plot about 1 000 m below the age-depth curve for the back-arc basins [Park et al., 1990] and about 2000 m below the Parsons and Sclater’s curve for the oceanic crust [Parsons et Sclater, 1977]. More generally, eastern Indonesia is characterized by large vertical motions. Strong subsidence is observed in the deep basins and in the Banda Ridges. On the contrary, large uplifts characterize the islands with rates ranging between 20 to 250 cm/kyr [De Smet et al., 1989a]. Excess subsidence in the back-arc basins has been attributed to large lateral heat loss due to their small size [Boerner et Sclater, 1989] or to the presence of cold subducting slabs. In eastern Indonesia, these mechanisms can explain only a part of the observed subsidence. It is likely that we have to take into account the tectonic forces linked to plate convergence. This is supported by the fact that uplift motions are clearly located in the area of active collision. In conclusion, the bathymetry and morphology of eastern Indonesian basins reveal a tectonically very active region where basins opened successively in back-arc, intra-arc and fore-arc situation in a continuous convergent geodynamic setting.

Waves generated by South Atlantic storms are greatly responsible for the beach and coastal erosion verified at the central coast of Rio Grande do Sul State, Brazil. These beaches are classified as intermediate, according to the morphodynamic approach suggested by the “Australian School of Coastal Geomorphology”. The storm wave regime controls the morphodynamic variability of those sandy beaches. Through the classification proposed by Dolan and Davis (1992). South Atlantic storms were classified and related to meteorological systems, considering corresponding beach responses. Out of the 3 year wave gauge storm data analyzed, 54.4% corresponded to Class I (weak), 23% to class II (moderate), 19.25% to class III (significant), 2.75% to class IV (severe) and for class V (extreme), 1 storm was recorded (0.6%). Coincidently, the proportion of storm class frequencies for the 3 year data of South Atlantic storms showed to be similar to the 42 year data studied by Dolan and Davis (1992) for North Atlantic storms. Such classification has proved to be effective for the southern Brazilian coast. Autumn and winter are the storm periods with greatest intensity, wich associated to maximum spring tides and storm surges generate the erosion cicle at this coast. The inverse process is verified to spring and summer, when the accretion cicle takes place. In addiction to this seasonal behavior trend, a continuous process of erosion without further recovering occurred at Conceição Lighthouse and Lagamarzinho beach locations, at rates of 3,6 meter per year and 1 meter per year respectively. The use of such method made possible quantifying storm intensity and establishing its relationship to seasonal erosion processes taking place in the southern Brazilian beaches.