bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of spatial relationships among geomorphic, petrographic and structural characteristics of the dartmoor tors
Authors: Ehlen Judy 
Published: February 2007

AbstractThe granite tors of Dartmoor are characterized by using the regional spatial patterns of 21 geomorphic, petrographic, and structural variables. The data were derived from topographic maps, field measurement, and laboratory analysis of rock samples collected in the field. Identification of spatial patterns and comparison of patterns between variables were made on contour maps generated from the data using ARC/INFO. Three tor types—summit tors, valleyside tors, and spur tors—are semiquantitatively characterized using these data and procedures.The three types of tors are distinguished with respect to variations in relative relief, joint spacing and joint type, rock texture, grain size, and composition. Summit tors have the highest relative relief (mean: 125·7 m), contain the most potassium feldspar (>30 per cent), and have the most widely‐spaced primary vertical (>300 cm) and secondary horizontal joints (> 10 cm). The rocks are the most megacrystic (> 15 per cent) and the coarsest grained. Plagioclase is also abundant in summit tors. Valleyside tors have the lowest relative relief (mean: 72·9 m) and the most widely‐spaced horizontal joints (primary, 60‐200 cm; secondary, > 10 cm). Grain size, vertical joint spacing, and quartz and potassium feldspar abundances are intermediate. The shapes of valleyside tors are controlled by horizontal joints and the rocks are either very feebly magcrystic or equigranular in texture. Spur tors have intermediate relative relief (mean: 115·4 m), the narrowest joint spacing (vertical joints, < 200 cm, 50‐75 cm; horizontal joints <60 cm, < 10 cm) and the finest grain. In addition, the rocks are feebly magacrystic.
Geomorphic activity of rabbits on a coastal sand dune, De Blink dunes, the Netherlands
Authors: Rutin J. 
Published: February 2007

AbstractA study of the erosion rate and the stability of sandy slopes was conducted on an eastern arm of a parabolic coastal sand dune, De Blink, central Netherlands. The contribution of rabbits to these processes was found to depend on two types of activity; the building of caves and sand mounds of up to 1·5 m2 in area; and the digging of shallow burrows, whereby amounts of sand up to 1 kg per burrow were excavated. The burrowing activity was found over the whole dune, while cave holes were dug mainly on the northern slope. The total amount of sand actually transported on the dune due to this activity is not clear yet, but their influence on the development of stepped slopes is well established.
Long‐term landscape evolution in Australia
Authors: Gale Stephen J. 
Published: February 2007

AbstractThe main features of the Australian physical landscape are of the order of 107‐108 years old. This contradicts the widely held view that little of the Earth's topography predates the Quaternary and that erosion cycles are carried to planation within tens of millions of years. Much of the Australian landscape must have developed over similar timescales to that of the tectonic evolution of the continent itself. The study of the geomorphology of such ancient terrains may therefore be seriously deficient unless it is considered within the context of continental‐scale tectonic development. Application of this approach shows that there are strong links between the geomorphology of Australia and plate movements, ocean spreading, plate convergence, tectonostratigraphic terranes, orogenesis and epeirogenesis.The most important factor contributing to the survival of ancient landscapes in Australia is the low rate of denudation which the continent has experienced during the Mesozoic and Cenozoic. This is largely a consequence of orogenic stability, although the absence of significant Quaternary glaciation may also be of importance. However, in order for landforms to have survived over such timespans, denudation must not only have been low, but must also have been highly localized over space and time. This has been the case both on a regional scale, with long‐term denudation rates of 0‐2 m Ma−1 in central Australia contrasting with higher rates along the continental margins, and on a local scale, with denudation confined to valleys, leaving divides and interfluves almost unscathed.
Geomorphological development of the eastern margin of the Australian Craton
Authors: Twidale C. R. , Campbell E. M. 
Published: February 2007

AbstractThe denudation chronologies of five uplands of contrasting geological structure located at the eastern margin of the Australian Craton are examined. They are the Isa Highlands, MacDonnell Ranges and Flinders Ranges (fold mountains, orogenic setting); the Arcoona Plateau (dissected plateau, platform setting); and the Gawler Ranges (massif of old silicic volcanics, cratonic setting). In each, surfaces of Mesozoic age, many of them exhumed and of pre‐Cretaceous age, are preserved. Each also appears to have been uplifted recurrently. Each was either overwhelmed or bordered by the Early Cretaceous (Neocomian‐Aptian) sea.Tectonism associated with the break‐up of Gondwana probably allowed this important marine transgression. Thereafter, thalassostatic and erosional/depositional isostatic responses have maintained the uplands as uplands and the intervening basins as negative topographic and structural units; the pattern of topography has been constant for the last 60–100 Ma.
Problems in automated recognition of valley features from digital elevation models and a new method toward their resolution
Authors: Tribe Andrea 
Published: February 2007

AbstractValley recognition methods given in the literature fail to produce valley networks suitable for locating valley heads for one of two main reasons: (a) they are based on the concept of [higher than] or (b) they are based on contributing area thresholds. In this paper a new method for recognizing valley bottoms is presented. This is based on two improvements of Carroll's (1983) method, and produces a network that reflects the topography well. The network is used to locate valley heads. Once located, the valley heads are delineated using criteria suggested by geomorphologists and hydrologists. The resultant valley heads are generally well recognized although two problems are evident: (a) there are a number of commission errors; and (b) the valley heads recognized by the method are too small.
Relationship between discharge, velocity and flow area for rills eroding loose, non‐layered materials
Authors: Govers Gerard 
Published: February 2007

AbstractA relationship between discharge, flow velocity and flow area in rills is established using data from four field and laboratory studies. The proposed relationship is shown to predict successfully flow velocities measured in six other studies. Although slopes range from 0.035 to 0.45 and soil materials range from stony sands over silt loams to vertisols, mean flow velocity can be well predicted from discharge alone. Thus, there is no important influence of slope and/or soil material characteristics on flow velocities in rills. The proposed relationship may be used to improve performance of deterministic flow routing models when applied to rilled catchments. Furthermore, it allows the calculation of unit stream power, which has been shown to be related to the transporting capacity of overland flow, in terms of slope and discharge.
Floodplain storage of mine tailings in the belle fourche river system: A sediment budget approach
Authors: Marron Donna C. 
Published: February 2007

AbstractArsenic‐contaminated mine tailings that were discharged into Whitewood Creek at Lead, South Dakota, from 1876 to 1978, were deposited along the floodplains of Whitewood Creek and the Belle Fourche River. The resulting arsenic‐contaminated floodplain deposit consists mostly of overbank sediments and filled abandoned meanders along White‐wood Creek, and overbank and point‐bar sediments along the Belle Fourche River. Arsenic concentrations of the contaminated sediments indicate the degree of dilution of mine tailings by uncontaminated alluvium.About 13 per cent of the 110 × 106 Mg of mine tailings that were discharged at Lead were deposited along the Whitewood Creek floodplain. Deposition of mine tailings near the mouth of Whitewood Creek was augmented by an engineered structure. About 29 per cent of the mine tailings delivered by Whitewood Creek were deposited along the Belle Fourche River floodplain. About 60 per cent of that sediment is contained in overbank deposits. Deposition along a segment of the Belle Fourche River was augmented by rapid channel migration. The proportions of contaminated sediment stored along Whitewood Creek and the Belle Fourche River are consistent with sediment storage along the floodplains of perennial streams in other, similar sized watersheds.
Textural analysis and modelling of a flood deposit: River severn, U.K.
Authors: Marriott Susan 
Published: February 2007

AbstractSamples of sediment collected from the Severn floodplain between Worcester and Gloucester following the severe flooding in January and February 1990, were analysed for their grain size distribution. The results show that most sand was deposited within 20 m of the channel bank, but that fine sand may contribute to flood sediment across the width of the floodplain. James' (1985) numerical model of overbank sedimentation attempts to predict the transfer of sediment to the floodplain during flooding. Geometrical and hydraulic data relating to the Severn flood are used as input for a computer program of James' (1985) model. The pattern of sediment concentrations predicted by the model was compared with that obtained from statistical analysis of the flood sediment. The patterns were found to be similar, so James' (1985) model was considered to predict in a relative sense the distribution of flood sediment.
Fault‐generated mountain fronts in the central apennines (Central Italy): Geomorphological features and seismotectonic implications
Authors: Blumetti Anna Maria , Dramis Francesco , Michetti Alessandro Maria 
Published: February 2007

AbstractThe morphotectonic framework of the Central Apennines is given by faulted blocks bounded by normal faults, mostly trending NW–SE, NNW–SSE and NE–SW, which cut previous compressive structures. Such a structural setting is consistent with the focal mechanisms of the earthquakes which often occur in this area.In this paper, three lithologically different normal fault‐generated mountain fronts are analysed in order to assess the relations between their geomorphic features and active tectonics. They border the Norcia depression (Sibillini Mts, Umbria), the Amatrice–Campotosto plateau (Laga Mts, Lazio) and the Fucino basin (Marsica Mts, Abruzzi).The Norcia depression is bounded by a N20°W trending normal fault to the east and by a parallel antithetic fault to the west. The main fault has a 1000 m throw and gives rise to a wide fault escarpment, characterized by: (1) sharp slope breaks due to low angle gravity faults; (2) important paleolandslides; and (3) several fault scarplets on the piedmont belt affecting Quaternary deposits.The Amatrice–Campotosto plateau is delimited by the western slope of Mt Gorzano which runs along a N20°W trending normal fault having a 1500m throw. Minor parallel faults dislocate Quaternary landforms. Large‐scale massmovements also occur here.The Fucino basin was struck by the 1915 Avezzano earthquake (I=XI MCS) which produced extensive surface faulting along two parallel NW trending normal fault escarpments on the eastern border of the basin. There is paleoseismic evidence including buried gravity graben in Late Glacial gravels and tectonic dip‐slip striations on Holocene calcitic crusts covering bedrock normal fault planes.These data suggest that active extensional tectonics plays a major role in the slope morphogenesis of the Central Apennines and they indicate the importance of geomorphic analysis in seismic zonation of this area.
Salt weathering simulation using a single‐immersion technique
Authors: Goudie A. S. 
Published: February 2007

AbstractSamples of concrete were subjected in an environmental cabinet to six different diurnal cycles of temperature and humidity change representative of desert surface conditions in the presence of a range of saturated salt solutions. The samples were not subjected to repeated immersion or continuous partial immersion as has been the case in most previous experiments. Breakdown did occur nonetheless. The two most effective cycles were one from Egypt (with a very high daytime maximum) and one from the Negev (with high nocturnal humidity conditions). Cycles with relatively modest temperature and humidity cycles were ineffective in causing debris liberation.
Identification of topographic settings conducive to landsliding from dem in Nelson county, Virginia, U.S.A.
Authors: Gao Jay 
Published: February 2007

AbstractThe steep terrains in the Blue Ridge Mountains of Virginia are potentially vulnerable to landsliding. Hundreds of slope failures were initiated by a severe storm in 1969 in Nelson County, Virginia. The outlines of 87 landslide scars were delineated on aerial photographs within a 28·8 km2 area. A digital elevation model (DEM) of the same area was constructed, from which three topographic variables (slope orientation, gradient and form) were derived. Overlay analyses of the landslide data and the topographic data, followed by chi‐square tests, revealed that the topographic variables studied are statistically significant to the spatial distribution of the sites disturbed by landslide paths. While the landsliding potential is low at very low and high elevations, it is found to be high in the median range of elevation. West‐, northwest‐, north‐ and northeast‐facing slopes are consistently more vulnerable to landsliding than their east‐, southeast‐, south‐ and southwest‐facing counterparts. Terrains with a gentle gradient are stable, but the potential for landslides to develop increases greatly as the terrains become steeper. The slopes with a concave cross‐section are more susceptible to landsliding than those having other shapes. Furthermore, the landsliding potential does not vary significantly with slope forms in the profile direction. It is concluded that the introduction of a DEM to this study has provided renewed insight into topographic settings conducive to landsliding which could not have been achieved otherwise.
A decade of surface change on a Namib linear dune
Authors: Livingstone Ian 
Published: February 2007

AbstractSurvey data from return visits to a linear dune in the Namib Desert provide information about change in dune form over a decade. The data demonstrate that, although change on these large features is slow, there is none the less considerable movement over this time‐scale. The dunes are therefore confirmed to be currently active and not Pleistocene relics.
The measurement of river bank erosion and lateral channel change: A review
Authors: Lawler D. M. 
Published: February 2007

AbstractA detailed review and chronological survey is presented of the various techniques which have been used for the measurement of river bank erosion and channel change. The techniques are classified according to the time scales involved (long, intermediate and short) and each is discussed with respect to accuracy and repeatability. The methods covered include sedimentological evidence, botanical evidence, historical sources, planimetric resurvey, repeated cross‐profiling, erosion pins and terrestrial photogrammetry. Prospects for future developments are also discussed.
Analysis of riverbank instability due to toe scour and lateral erosion
Authors: Thorne Colin R. , Abt Steven R. 
Published: February 2007

AbstractThis paper provides instruction in the use of the computer spreadsheet to undertake the calculations necessary to apply the Osman–Thorne bank stability analysis for steep, eroding riverbanks. The guide explains how to input the necessary parameters into the LOTUS 123 spreadsheet in order to:

find the initial factor of safety of the bank with respect to slab‐type failure;
test the sensitivity of bank stability to changes in the engineering properties of the bank material;
analyse the response of bank stability to toe scour and/or lateral erosion and find the critical condition;
find the geometry of the failure surface and failure block;
analyse the response of bank stability to further toe scour and/or lateral erosion;
find the geometry of the failure surface and failure block in subsequent failures.
Erosional effects of cattle on streambanks in Tennessee, U.S.A.
Authors: Trimble Satanley W. 
Published: February 2007

AbstractThe geomorphological effects of cattle on streambanks in a humid region, which have consequent potential effects on water quality, are examined. Field observations suggest that cattle are important agents in causing streambanks to erode, but so many variables are involved that it is difficult to isolate the role of cattle. Instead, an empirical approach based on long‐term controlled experiment was adopted along a small perennial stream in the Central Basin of Tennessee. The results showed that uncontrolled grazing caused about six times as much gross bank erosion as occurred on the protected control stretch. However, most of this difference was due to breakdown of banks by trampling and consequent erosion, rather than by bank scour caused by removal of bank vegetation by grazing. That is, bank vegetation alone did not appear to be a primary control. A relatively inexpensive grade‐control structure reduced the gross bank erosion by about 50 per cent. The rapid destruction of streambanks observed in this study suggests that reduction of geomorphic resistance by uncontrolled stock access to streambanks has been an important factor in the stream widening that has taken place during historical time in the eastern United States.
Steady state behaviour of the black ven mudslide: The application of archival analytical photogrammetry to studies of landform change
Authors: Chandler J. H. , Brunsden D. 
Published: February 2007

AbstractThe concept of dynamic equilibrium has provided geomorphologists with a challenging paradigm for studying landform evolution but quantitative evidence for its existence has proved illusive, particularly for complex geomorphological systems. The authors believe that the principle has now been verified through the application of the ‘archival photogrammetric technique’ to a sequence of historical photographs spanning 50 years of process at the Black Ven mudslide complex in Dorset, U.K.The principles and limitations of the archival photogrammetric technique are described. The method is applied to oblique and vertical aerial photographs of Black Ven at five epochs, commencing in 1946, continuing at approximately 10 year intervals until 1988. The technique is used to generate plans/contours/sections and a dense and accurate digital elevation model (DEM) of the whole site at each epoch. This is used to generate ‘DEMs of difference’ and a ‘distribution of slope angle’ which suggest that the mudslides are in equilibrium despite the removal of 200 000 m3 of sediment between 1958 and 1988. Extrapolation of the slope distribution through time suggests that the frequency of an episodic landform change model at Black Ven may be approximately 60 years.
Sediment routing analyses based on chronological changes in hillslope and riverbed morphologies
Authors: Nakamura Futoshi , Maita Hideji , Araya Tohru 
Published: February 2007

AbstractRecent studies of sediment delivery and budgets in the United States indicate that upland erosion rates at a given time may not explain contemporaneous sediment yields from a drainage basin. This suggests temporal discontinuities in sediment delivery associated with hillslope and channel storage processes. Integration of sediment production, storage and transport is essential to understand sediment routing in basins. We analysed each process chronologically using aerial photographs, monitoring data of sediment movement and annual tree‐rings, and then compared estimated temporal changes in sediment production from hillslopes, floodplain disturbance areas and sediment transport in river channels. Toeslopes, floodplains and alluvial fans together contained 59 per cent of sediment eroded from uplands over the last 30 years. Monitoring results of riverbed changes showed that the volume of stored sediment on floodplains decreased exponentially with succeeding floods. The age distribution of floodplain deposits reflected the disturbance history of a river channel, and followed an exponential decrease with age. The results of this study may have important implications for sediment control plans for watersheds in steep regions.
Rapid formation of rock varnish and other rock coatings on slag deposits near Fontana, California
Authors: Dorn Ronald I. , Meek Norman 
Published: February 2007

AbstractManganiferous rock varnish, silica glaze and iron skins have formed on 20‐ to 40‐year‐old slag piles near Fontana, southern California. Rapid rock‐varnish formation is associated with an unidentified cocci bacterium that grows rapidly in culturing experiments, combined with the likelihood that Mn‐rich solutions flow over slag surfaces. A new model is proposed for the formation of silica glaze, involving soluble Al‐Si complexes and the nature of wetting films. Iron skins occur where runoff is concentrated, and where iron bacteria grow.Observations indicate: (i) substrate can be important in supplying Mn, as well as maintaining a stable surface and channelling runoff to microspots where varnish grows; (ii) ignorance of boundary layer pH/Eh conditions makes chemical‐physical models of varnish formation speculative; (iii) the balance between cementation of recently nucleated varnishes and erosional shear stresses is poorly understood, but is probably an important limiting factor on varnish growth rates; and (iv) there must be at least two steps in biotic varnishing‐accretion of Mn‐Fe in casts, followed by cementation of clays by either in situ cast residue or Mn‐Fe remobilized from casts. Varnish accretion may be limited by the rate at which both steps occur. Rapid development of readily distinguishable manganiferous rock varnishes at this post‐1952 site highlights the danger of speculation on the ages of landforms based solely on the appearance of rock‐varnish coatings.
Rates of rock surface lowering, Princess Elizabeth land, Eastern Antarctica
Authors: Spate A. P. , Burgess J. S. , Shevlin J. 
Published: February 2007

AbstractA series of micro‐erosion‐meter sites on different rock types and in differing wind regimes was established and re‐read after four years on two sites in the Larsemann and Vestfold Hills. These two oases in Eastern Antarctica are subjected to both wind abrasion and salt wedging. The measurements displayed bimodal distributions, indicating that both abrasion and single‐grain detachment could be observed. Surface lowering rates of 0·015 and 0·022 mm a−1 were demonstrated for the Larsemann and Vestfold Hills, respectively.