No description available.

Construction of a 1:250,000 scale regolith-landform map of the Cobar area of central New South Wales (NSW) Australia, demonstrates the presence of a wide range of previously undescribed regolith materials, landforms and landscape features in the region. The map covers the east-west extent of the Cobar Basin, extends to the west onto the Darling River Floodplain, and east onto rocks of the Girilambone Group. The mapping area is centred on the Cobar township and covers -14,730 krn2 between 303113 and 446113 E and 6483184 and 6586183 N (AGO 66, MGA Zone 55). 48 regolithlandform units have been identified, including both transported (alluvial, colluvial, aeolian, lacustrine) and in situ materials. A range of siliceous, ferruginous and calcareous indurated materials are also present. Four major drainage types have been identified based on lithological, sedimentological and topographic differences in alluvial materials. The 4 drainage types include: 1) modern drainage; 2) maghemite and quartzose gravels elevated 1-2 m relative to the modern drainage; 3) higher topographically inverted, and at least partly silicified, gravels; and, 4) sediments of Cretaceous origin. Multiple phases of drainage stability and instability from the Cretaceous to the present are indicated within the sediments. Breaching of drainage divides and increased dissection of the modern drainage, especially to the south of Cobar, indicate possible tectonic movement across a major regolith-landform boundary in the southern map area. Colluvial materials are more widespread to the north of Cobar reflecting the increased landscape dissection to the south. Colluvial fans are preserved adjacent to major rangefronts. Aeolian and lacustrine materials include longitudinal dunefields of the Darling River floodplain, source bordering dunes, and small lunettes associated with the Barnato Lakes system. Regolith-landform mapping at Cobar has been used to assess the applicability of previously developed landscape evolution models of the Cobar Block and surrounding region, and to develop a new landscape evolution model for the region. The new landscape evolution model of Cobar indicates minimal deposition of Cretaceous sediments, succeeded by high-energy early Tertiary fluvial regimes across the Cobar landscape. Weathering and sediment deposition continued into the Miocene, coupled with deep valley incision on the Cobar Block associated with early Oligocene regression. By the close of the Miocene, the Cobar Block had eroded to predominantly bedrock terrain and widespread filling of previously incised valleys occurred. A decrease in erosion and fluvial activity led to the formation of the modern drainage during the Pliocene-early Quaternary, followed by the formation of alluvial, aeolian and lacustrine deposits in the later Quaternary. Regionally, Eromanga Basin sediments were not extensive over the Cobar Block, and low rates of erosion are recorded at Cobar from the Cretaceous to the present. Former northerly drainage did exist in this area in the Cretaceous, but was limited in distribution. By at least the Early Tertiary the Cobar area was a structural high and drainage systems of the region had assumed their current configuration. These findings do not support interpretations of AFTT data of significant cover and subsequent stripping over the Cobar Block in the Early Tertiary. Evidence of landscape evolution from the Cretaceous to the present suggests that the Cobar landscape has been responding to changes in the primary landscape forming factors of lithology, climate and to a lesser degree, tectonics. Variations in the these three primary landscape forming factors have contributed to ongoing weathering, relatively continuous deposition, and periods of relative stability and instability, particularly in response to climatic and baselevel fluctuations, within a dynamically evolving landscape throughout the entire Tertiary. Former landscape evolution models of peneplanation and pediplanation, based on correlation of palaeosurfaces including duricrusts, a deep weathering profile developed during extended planation in the Early Tertiary, and tectonism during the late Tertiary in the Cobar area, are not supported by evidence preserved in regolith-landform features at Cobar.

Landscape evolution is important for mineral and petroleum exploration concepts, especially in dryland continental settings. This study seeks to understand the main issues and controls on landscape evolution that have produced the regolith and young sediments around the western side of Lake Eye, in the arid heart of Australia. Several methods were employed including satellite image analysis, geomorphometry, geological mapping, regolith mapping and surveying. Outcomes indicate that the underlying structural fabric of the basement has controlled the development of the surface morphology of the Umbum Creek Catchment. The arrangement of basement faults is reflected in the distribution of surface landforms and in the topography of the land surface. Significant deformation of the Etadunna and Eyre formations indicate tectonic activity occurred at the end of the Miocene and was probably related to movement in the Lake Eyre Fault Zone. Pleistocene faulting is expressed as minor blind faulting associated with pre - existing basement faults. These faults remain active and current seismic activity is driven by changes in hydrostatic pressure (hydroseismicity). The scale of Pleistocene faulting and modern seismic activity demonstrates that since the Pliocene tectonic activity has been subdued. Climate change caused landforms developed under wet conditions during the Palaeogene and Neogene to be preserved by the development of aridity in the Pleistocene. High erosion rates associated with tectonism and the onset of aridity in the Pleistocene led to topographic inversion of many features. Palaeo-Proterozoic inliers formed inselbergs, silcrete outcrops formed capstones, gypsum hardpans protected underlying sediment from erosion creating plateaux of gypsum patterned ground and palaeo-channels on the Neales Fan were eroded to make heavily armoured mounds and associated sand dunes and sand sheets. The dominant factor influencing the evolution of the landscape in the Umbum Creek Catchment was the deposition of sedimentary sulphides within the Bulldog Shale. The excess sulphur that this sediment supplied to the landscape over time created the necessary conditions for the formation of a range of landscape features that would not otherwise exist. Weathering, oxidation and leaching of the sedimentary sulphides led to the development of silcrete. Subsequent weathering and tectonic activity led to the breakdown of the silcrete and the distribution of silcrete pebbles widely across the landscape forming gibber plains. Sulphur from the Bulldog Shale continued to contribute to the landscape forming intra-formational gypsum and precipitating as gypsum hardpans. This study has implications for petroleum exploration in dryland continental settings as potential reservoirs may be affected by secondary diagenetic processes, such as the formation of gypsum or silcretes, that could act as baffles or result in reduced porosity within the reservoir. The broad-scale architecture of fluvial systems, like the Neales Fan, may not conform to traditional fan-shaped models being, instead, comprised of structurally rearranged channels. In terms of earthquake risk assessment, the identification of hydroseismicity active within the Lake Eye Basin allows for a new level of predictability of earthquake behaviour within Central Australia. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1260856 / Thesis (Ph.D.) -- School of Earth and Environmental Sciences, 2006

<p>Kongsfjordhallet is situated at 79° N on the North coast of Kongsfjorden, Spitsbergen.The landscape shows a large diversity of landforms and sediments and the aim of thisstudy has been to investigate the spatial distribution and temporal differences betweenthese landforms.The most prominent landform is interpreted as a lateral moraine dividing the area fromsoutheast to northwest. This is probably a sign of a standstill during the deglaciation ofan ice-sheet glacier tongue filling the fjord. The valley-glaciers at Kongsfjordhallet haveadvanced after this event and left end moraines on top of the lateral moraine. Largeamounts of meltwater have eroded parts of the Kongsfjordhallet, creating several fossilmeltwater channels that dissect the landscape. Erratic boulders of mainly gneiss type arescattered all over the landscape, as high up as 500 m a.s.l. In addition to the erraticboulders, a lot of allochthonous material is found incorporated in local material,especially as a diamict interpreted as till that covers large parts of Kongsfjordhallet.The till can likely be correlated to one of the diamict units in the cliff sections at theKongsfjordhallet coast. At present, two large ravines drain the area, moving water fromthe glaciers to the ocean and a beach is developing in the Southeast part of the area dueto ocean transgression. Landforms from two glacial events are found, one regional andone local. An episode of high sea-level as well as fluvial and mass-wasting activity afterthe deglaciation is also recorded. The formation of the landforms in the area is believedto be after the Last Glacial Maximum and into the Holocene, but no absolute dates areavailable.</p> / SciencePub

Terrain as a continuum can be categorized into landform units that exhibit common physiological and morphological characteristics which might serve as a boundary condition for a wide range of application domains. However, heterogeneous views, definitions and applications on landforms yield inconsistent and incompatible nomenclature that lack interoperability. Yet, there is still room for developing methods for establishing a formal background for general type of classification models to provide different disciplines with a basis of landscape description that is also commonsense to human insight. This study proposes a method of landform classification that reveals general geomorphometry of the landscape. Landform classes that are commonsense to human insight and relevant to various disciplines is adopted to generate landforms at the landscape scale. Proposed method integrates local geometry of the surface with geomorphometric context. A set of DTMs at relevant scale are utilized where local geometry is represented with morphometric DTMs, and geomorphometric context is incorporated through relative terrain position and terrain network. &ldquo / Object-based image analysis (OBIA)&rdquo / tools that have the ability to segment DTMs into more representative terrain objects and connect those objects in a multi-level hierarchy is adopted. A fuzzy classification approach is utilized via semantic descriptions to represent ambiguities both in attribute and geographical space. Method is applied at different case areas to evaluate the efficiency and stability of the classification. Outcomes portray reasonable amount of consistency where the results can be utilized as general or multi-purpose regarding some ambiguity that is inherent in landforms as well.

No description available.

Die automatisierte Objektidentifikation stellt ein modernes Werkzeug in den Geoinformationswissenschaften dar (BLASCHKE et al., 2012). Um bei thematischen Kartierungen untereinander vergleichbare Ergebnisse zu erzielen, sollen aus Sicht der Geoinformatik Mittel für die Objektidentifikation eingesetzt werden. Anstelle von Feldarbeit werden deshalb in der vorliegenden Arbeit multispektrale Fernerkundungsdaten als Primärdaten verwendet. Konkrete natürliche Objekte werden GIS-gestützt und automatisiert über große Flächen und Objektdichten aus Primärdaten identifiziert und charakterisiert. Im Rahmen der vorliegenden Arbeit wird eine automatisierte Prozesskette zur Objektidentifikation konzipiert. Es werden neue Ansätze und Konzepte der objektbasierten Identifikation von natürlichen isolierten terrestrischen Oberflächenformen entwickelt und implementiert. Die Prozesskette basiert auf einem Konzept, das auf einem generischen Ansatz für automatisierte Objektidentifikation aufgebaut ist. Die Prozesskette kann anhand charakteristischer quantitativer Parameter angepasst und so umgesetzt werden, womit das Konzept der Objektidentifikation modular und skalierbar wird. Die modulbasierte Architektur ermöglicht den Einsatz sowohl einzelner Module als auch ihrer Kombination und möglicher Erweiterungen. Die eingesetzte Methodik der Objektidentifikation und die daran anschließende Charakteristik der (geo)morphometrischen und morphologischen Parameter wird durch statistische Verfahren gestützt. Diese ermöglichen die Vergleichbarkeit von Objektparametern aus unterschiedlichen Stichproben. Mit Hilfe der Regressionsund Varianzanalyse werden Verhältnisse zwischen Objektparametern untersucht. Es werden funktionale Abhängigkeiten der Parameter analysiert, um die Objekte qualitativ zu beschreiben. Damit ist es möglich, automatisiert berechnete Maße und Indizes der Objekte als quantitative Daten und Informationen zu erfassen und unterschiedliche Stichproben anzuwenden. Im Rahmen dieser Arbeit bilden Thermokarstseen die Grundlage für die Entwicklungen und als Beispiel sowie Datengrundlage für den Aufbau des Algorithmus und die Analyse. Die Geovisualisierung der multivariaten natürlichen Objekte wird für die Entwicklung eines besseren Verständnisses der räumlichen Relationen der Objekte eingesetzt. Kern der Geovisualisierung ist das Verknüpfen von Visualisierungsmethoden mit kartenähnlichen Darstellungen. / The automated object identification represents a modern tool in geoinformatics (BLASCHKE et al., 2012). In order to achieve results in thematic mapping comparable among one another, considering geoinformatics, means of object identification should be applied. Therefore, instead of fieldwork, multispectral remote-sensing data have been used as a primary data source in this work. Specific natural objects have been GIS-based and automatically identified and characterised from the primary data over large areas and object densities. Within this work, an automated process chain for the object identification has been developed. New approaches and concepts of object-based identification of natural isolated terrestrial landforms have been developed and implemented. The process chain is based on a concept that develops a generic approach to the automated object identification. This process chain can be customised for and applied to specific objects by settings of characteristic quantitative parameters, by which the concept of object identification becomes modular and scalable. The modul-based architecture enables use of individual moduls as well as their combinations and possible expansions. The introduced methodology of object identification and the connected characteristics of (geo)morphometric and morphologic parameters has been supported by a static procedures. These enable the comparability of object parameters from different samples. With the help of regression and variance analysis, relations between object parameters have been explored. Functional dependencies of parameters have been analysed in order to qualitatively describe the objects. As a result, automatically computed dimensions and indices of the objects can be captured as quantitative data and informations an applied to varied samples. Within this work the thermokarst lakes represent the basis for the process development and an example and a data basis for the design of the algorithm and analysis. The goevisualisation of multivariant natural objects has been applied to develop better understanding of their spatial relations. The essence of the geovisualisation is to link the methods of visualisation to map-like presentation.

No description available.

Consideration of almost any geomorphology textbook will show the fundamental argument that in cold environments mechanical weathering processes, usually freeze-thaw, will predominate and that chemical weathering will be temperature-limited, often to the point of non occurrence. These basic concepts have underpinned geomorphology for over a century and are the basis for the development of many landforms in periglacial regions. With the introduction of data loggers so field data became more readily available but, sadly, those data were not of a quality to other than justify the existent assumptions and thus did little more than reinforce, rather than test, the nature of our understanding of cold region weathering. Factors such as rock properties were dealt with to a limited extent but rock moisture was all but ignored, despite its centrality to most weathering processes. Here the results of field studies into weathering in cold regions, coupled with laboratory experiments based on the field data, are presented. An attempt is made to overcome the shortcomings of earlier studies. Temperature, moisture and rock properties have all been considered. Processes were not assumed but rather the data were used to evaluate what processes were operative. The results, both in terms of weathering process understanding per se and of its application to landform development, significantly challenge our longheld perceptions. Information is presented that shows that it is not temperature, but rather water, that is the limiting factor in cold region weathering. Indeed, in the absence of water, many cold environments have attributes akin to a hot desert. The relevance of this is that weathering processes other than freeze-thaw may play a significant role and that in the presence of water chemical weathering can play a far greater role than hitherto thought. Overall, the whole concept of zonality with respect to weathering is questioned. Finally, the attributes of weathering are put within the context of landform development and questions raised regarding the origin of some forms and of their palaeoenvironmental significance. Attributes of periglacial, glacial and zoogeomorphic processes and landforms in present and past cold environments are also presented. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2003.

Dartmoor Vlei is a 42ha un-channelled valley-bottom wetland system located in the headwaters of the Myamvubu River in the KwaZulu-Natal Midlands, South Africa. The wetland and its catchment are entirely underlain by a large dolerite sill that forms the Karkloof escarpment and plateau and the wetland terminates against a dolerite dyke ridge that has intruded into the sill. Wetlands on the Highveld and KwaZulu-Natal Midlands are thought to arise due to the lateral erosion of valleys upstream of resistant lithologies that impede vertical erosion. This is typical of valleys where Karoo sediments occur upstream of resistant dolerite dykes. Such valley widening by lateral planing is typically associated with actively migrating meanders. As a result, wetlands found upstream of dolerite intrusions are generally located on floodplains characterised by actively migrating meanders, extensive backswamps, ox bow lakes, alluvial ridges and clastic alluvial fill. However, in contrast to these floodplain wetlands, Dartmoor Vlei has evolved into an unchannelled valley-bottom wetland characterised by diffuse flow conditions, minimal channelled flow, extensive peat deposits and a general lack of floodplain features. Coring within the wetland has established that the sedimentary fill of the wetland generally comprises upward fining sequences of sediment characterised by sands and gravels near the valley floor that grade into fine organic-rich silt sediments and peat at the surface. These findings confirmed that the wetland has evolved from a floodplain wetland characterised by laterally migrating meanders to a valley-bottom wetland characterised by discontinuous streams and peat accumulation. Coring also established that the wetland is predominantly underlain by residual saprolite that extends to depths in excess of 7m. The occurrence of a large discontinuity between the residual saprolite and fresh dolerite surfaces underlying the toe of the wetland indicated that the residual saprolite surface has sagged relative to the fresh dolerite and dolerite dyke at the toe of the wetland over time. Chemical and mineralogical analyses of fresh dolerite and residual clay within the valley confirmed that the chemical transformation of the dolerite bedrock into residual clay has resulted in both volume and thickness losses in the weathered dolerite sill mass. This has in turn resulted in the sagging of the valley floor and the wetland surface over time. These findings provide an explanation for the extremely low energy conditions of Dartmoor Vlei and explain why the wetland did not evolve in the same fashion as other wetlands in a similar geological and geomorphological setting. The extensive chemical weathering of the dolerite sill underlying the wetland has been attributed to the extremely long-time period that the soils within the wetland have been saturated. The long-term saturation of soils within Dartmoor Vlei has been facilitated by the formation and preservation of the African Erosion Surface on which Dartmoor Vlei is located. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2009.