bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rapid honeycomb weathering (tafoni formation) in greywacke, S.E. AUSTRALIA
Authors: Gill Edmund D. 
Published: February 2007

AbstractThe development of honeycomb weathering on seawalls of non‐marine Lower Cretaceous greywacke built in 1943 and 1949 shows that under certain conditions this type of tafoni is a significant factor in the retrogradation of rocky coasts.
Micro‐topographic change on calcarenites, grand Cayman Island, West Indies
Authors: Spencer T. 
Published: February 2007

AbstractChanges in micro‐topography, as a result of varying erosion rates, have been monitored on a calcarenite ridge on Grand Cayman Island, West Indies, using a traversing model of the micro‐erosion meter. Erosion takes place through the solution of a calcitic cement and ‘solutional disintegration’ results in a rapid change of micro‐relief. Where a protective crust is present, surface lowering is slower and also more uniform; thus the original relative relief is maintained.
A test of granulometric control of desert dune geometry
Authors: Wasson R. J. , Hyde R. 
Published: February 2007

AbstractI. G. Wilson's hypothesis of coarse‐tail grain‐size control of dune spacing was derived from three dunefields in the Sahara and, although it was supplemented by measurements of spacing from other parts of the world, the grain‐size data come only from North Africa. In this paper the hypothesis is tested in the Australian dunefields. Australian dunes do not form separate categories on a P20/s (twentieth percentile/spacing) plot and, when placed on Wilson's diagram, the Australian data form a continuum between dunes and draas. Ripples maintain their identity, suggesting that the average saltation length of sand controls ripple wavelength while dunes and Wilson's draas are formed by secondary flow of some kind. In Australia the spread of data on the P20/s diagram indicates that grain‐size is not the prime control on s. Data from Australia and the Sahara indicate that direct linear relationships between s and h (dune spacing and height means respectively for blocks of dunes) occur but they have different slopes in different areas. These differences possibly reflect variations in vegetation and substrate as well as differences in wind regime. The separation of dunes from draas in the Sahara reflects the greater role of grain‐size in an area where coarse grains frequently occur in dune crests. The relative paucity of coarse grains in Australian dune crests may reflect the fine‐grained alluvium from which the dunes are derived. These differences may be ascribed to differing topography in Australia and the Sahara.
Accretion rates on some debris slopes in the Mt. Rae area, Canadian Rocky Mountains
Authors: Gardner James S. 
Published: February 2007

AbstractAccretion of debris was monitored on six slopes in the Mt. Rae area of the Canadian Rocky Mountains for the period 1975–1982. Monitoring was accomplished by measuring annually the accumulated debris on fabric mats which were placed on the long profile of the slopes. Annual rates of accretion were extremely variable between points on the same slope, between slopes, and between years. The data do not show a systematic decrease in accretion downslope but indicate that an absence of accretion is more likely on the lower half of the slopes. In general, annual rates are comparable to previously published values from the Rockies and the maximum rates of 30 to 40 mm per year are comparable to those from Karkevagge in Scandinavia. Extremely high rates of accretion were all related to extreme events such as debris flows or full depth snow avalanches. The variation in accretion rates is not explained by single environmental factors such as lithology and slope exposure.
The impact of afforestation on stream bank erosion and channel form
Authors: Murgatroyd A. L. , Ternan J. L. 
Published: February 2007

AbstractModification of the land use of a small catchment through coniferous afforestation is shown to have influenced stream bank erosion and channel form. Field mapping and erosion pin measurements over a 19‐month period provides evidence of more active bank erosion along forested channel reaches than along non‐forested. Extrapolation of downstream increases in bankfull width, bankfull depth, and channel capacity with increasing basin area for the non‐forested catchment has demonstrated that afforestation of the lower part of the catchment has had a marked effect on channel form. Channel widths within the forest are up to three times greater than that predicted from the regression. These changes in bankfull width have led to stream bed aggradation and the development of wide shallow channels within the forest, and channel capacities within the forest are over two times that predicted from the basin area. The relationship between channel sinuosity and valley gradient for non‐forested reaches of the river also indicated decreased sinuosity resulting from afforestation. These changes in channel form result from active bank erosion within the forest with coarse material being deposited within the channel as point‐bars and mid‐channel bars. Active bank erosion is largely attributed to the suppression by the forest of a thick grass turf and its associated dense network of fine roots, and secondly to the river attempting to bypass log jams and debris dams in the stream channel.
A pattern in the incidence of major coastal mudslides
Authors: Hutchinson J. N. 
Published: February 2007

AbstractThe communication considers eroding coastal cliffs which consist predominantly of stiff‐fissured clay overlying a more resistant stratum, the contact having a gentle component of coastwise dip. From the southern coasts of England, five such cliffs are described. In each of these a zone of dominant mudsliding exists, which stands out from the background of lesser mudslides and other forms of failure: the common feature is that in each case the zone of major mudsliding coincides closely with the length of cliff over which the base of the clay stratum lies within the tidal range, and generally within the upper part of this. It is suggested that this pattern results from optimum conditions for continuing stimulation of mudslide activity by toe erosion being reached in the above zone.
A statistical study of the cliff top slumps in part of the christchurch bay coastal cliffs
Authors: Barton M. E. , Coles B. J. , Tiller G. R. 
Published: February 2007

AbstractA distinction is made between slumping and spalling. Slumping involves a compound slide with rotation and translation: the latter along one of the bedding plane shear surfaces in the Barton Beds. Spalling is an isolated failure of the exposed cliff face due to weathering. Where slumping is the dominant mode of cliff top recession, the latter is an incremental process with the increments being equal to the breadth of the slumps. A statistical study has been made of the breadth, length and plan area of 42 slumps observed over a 2 km stretch of the Christchurch Bay coastal cliffs and significant trends deduced.
Suspended sediment in rapid subsurface stormflow on a large field plot
Authors: Pilgrim David H. , Huff Dale D. 
Published: February 2007

AbstractThe occurrence of rapid movement of suspended sediment in subsurface stormflow on a large field plot in California is described. Concentrations of over 1000mgl−1 were recorded in storms of only low to moderate intensity. The observed sediment was composed of uniformly fine‐sized particles 4 to 8 μm in diameter. The mode of transport seems different from processes previously reported. Differences in sediment concentrations in different events, levels of 137Cs on the sediment, and several other types of evidence indicate that the sediment was detached and entrained at the ground surface by raindrop impact and that the water and sediment flow occurred mainly through macropores in the soil. As conditions similar to those at the study site are not uncommon, it seems probable that the phenomenon may occur in many regions.
Rates of surface processes on slopes, slope retreat and denudation
Authors: Saunders Ian , Young Anthony 
Published: February 2007

AbstractResults taken from 270 publications on rates are summarized, and collated with those from 149 publications reviewed previously (Young, 1969, 1974). The data are classified by major climatic zone, normal or steep relief, and consolidated or unconsolidated rocks. Representative rates and their ranges are given for soil creep, solifluction, surface wash, solution (chemical denudation), rock weathering, slope retreat, cliff (free face) retreat, marine cliff retreat, and denudation, the last being compared with representative rates of uplift. Solifluction is of the order of 10 times faster than soil creep, but both cause only very slow ground loss. Solution is an important cause of ground loss for siliceous rocks, on which it may be half as rapid as on limestones. Total denudation, brought about mainly by surface wash, reaches a maximum in the semi‐arid and probably also the tropical savanna zones. Acceleration of natural erosion rates by human activities ranges from 2–3 times with moderately intense land use to about 10 times with intensive land use (and considerably higher still where there is recognized accelerated soil erosion). Where there is active uplift, typical rates are of the order of 10 times faster than denudation, although in some high, steep mountain ranges these may approach equality.
Frost action and hydration as rock weathering mechanisms on schist: A laboratory study
Authors: Fahey Barry D. 
Published: February 2007

AbstractRecently it has been proposed that stress generated by the adsorption of water to clay surfaces in argillaceous rocks may be an important agent of mechanical weathering in polar and alpine environments, implying that long‐held views on the status of frost action in these areas may be in need of revision.This study documents the response, under controlled experimental conditions, of aggregates of fresh and partlyweathered schist and fresh pre‐cut schist blocks to 500 accelerated (12 hour) freeze‐thaw and hydration‐dehydration cycles. Aggregate samples subjected to freezing cycles produced the largest amounts of material in the less than 2 mm size range (an average of 8 per cent and 16 per cent for the fresh and partly‐weathered aggregates respectively), whereas humidity cycles above and below freezing yielded lesser amounts (3 per cent and 4 per cent respectively). The fresh schist blocks were found to be highly resistant to both mechanisms; only those experiencing freeze‐thaw oscillations produced measurable amounts of detritus.Although hydration effects were not as effective as frost action in causing particle size reduction in aggregates, the two mechanisms may well reinforce one another in periglacial environments, enhancing the ability of these areas to serve as source regions for loess.
Lichenometric dating of debris‐flow deposits in the Scottish Highlands
Authors: Innes John L. 
Published: February 2007

AbstractDebris‐flow deposits, dated by lichenometry, indicate that the majority of hillslope debris flows in Scotland have occurred within the last 500 years. Progressive weathering and climatic change can be discounted as the prime cause of the increase in the incidence of debris flows. The timing of the increase suggests that it is related to landuse changes in the Scottish Highlands during the 19th and early 20th centuries. Both burning and overgrazing can be cited as potential causal factors.
The temporal and spatial development of landslides in the axmouth‐lyme regis undercliffs national nature reserve, Devon
Authors: Pitts John 
Published: February 2007

AbstractA chronology of landsliding is presented, including suggestions as to a date for initiation. Periods of activity known from historical sources are correlated with known periods of climatic deterioration. The current morphology of the landslide slopes is closely related to the geological succession and structure. These permit the landslides and their development to be differentiated on the basis of whole slope and toe morphology, and much of the whole‐slope activity can be related to conditions at the toe. Examples of geomorphological maps, slope categories maps, and cross sections are presented along with an example of the ‘evolutionary’ maps which may be derived from Ordnance Survey plans and aerial photographs. These generally indicate that weakening of materials by weathering, seepage erosion at the toe, and marine erosion result in frequent mass movement events of a low magnitude. These events ultimately influence the stability of larger slipped blocks behind, which fail less frequently. It is suggested that whole‐slope failures in this region have a maximum frequency of once in 120 to 150 years, and that problems of interpretation of historical accounts may mean that it is very much less frequent than this.
Response of the Ohau River and delta to lake level lowering
Authors: Mosley M. P. 
Published: February 2007

AbstractThe response of the Ohau River to a lowering of Lake Benmore of 4 m was monitored during a three‐month period when the river was carrying mean daily flows between 100 and 400 m3/s from a power station. Initially, the river degraded by up to 0·8 m for a distance of 1·3 km upstream from the lake, but during the 52‐day period of minimum lake level, the delta and lower channel aggraded by up to 0·4 m. During that period, an estimated 225 000 m3 of sediment was supplied to the delta, sufficient for rapid progradation of the delta front into the shallow lake and the observed aggradation of the channel and delta surface. Other factors, in this case receiving‐basin geometry and sediment yield, may thus control the response of a river‐delta system to relative base‐level lowering.
The pre‐glacial evolution of Wales
Authors: Battiau‐Queney Yvonne 
Published: February 2007

AbstractThe classical explanation of the development of the Welsh landscape by the effects of a pulsed ‘eustatic’ uplift during the Cenozoic times is challenged by new data on the geology and geomorphology of Wales and the adjacent regions.The post‐Caledonian surface developed over most of Wales in the upper Westphalian plays a major role in landform development. Since its emergence before mid‐Cretaceous times, the Welsh Massif has suffered a long subaerial evolution which favoured a powerful chemical weathering. In Anglesey and St. David's Land, residual hills were formed by a process of differential weathering, and downwearing in saprolites. The Millstone Grit quartzites have been deeply weathered and dolines or flat‐bottomed basins have been developed.From Cretaceous to Miocene times, a morphotectonic equilibrium has existed between uplift and denudation, so that, in the major part of Wales, the original planation surface was constantly maintained by lowering on itself and in some places it is possible to prove that no more than a few dozen metres of rock thickness disappeared during that period. Several main escarpments were produced by the warping of the planation surface along sharp flexures, during Neogene times. The Cenozoic vertical movements were controlled by the Caledonian or pre‐Caledonian tectonic pattern which has divided the continental crust into major structural units.Welsh tectonic development is related to the opening of the North Atlantic, associated stresses reactivating ancient lines of weakness in the heterogeneous lower crust or upper mantle.
Rate of soil erosion processes on vineyards in central Piedmont (NW Italy)
Authors: Tropeano Domenico 
Published: February 2007

AbstractThe ‘Tertiary Basin of Piedmont’ is a hilly region, mainly composed of marine sediments, such as marls, silts and sands. The slopes, largely devoted to grape production, are usually kept bare of vegetation and are thus prone to soil erosion processes. For two years we have measured soil loss in relation to rainfall on experimental plots located in vineyards. In all the plots considered erosion started with low rainfall intensities (0·07 mm/min), and above 0·4 mm/min the amount of soil loss dramatically increased (to over 1800 g/m in one event). Most of the erosion occurs during summer rainstorms, but the behaviour of the soil under erosive rainfalls is very different from one site to another, depending only in part upon the various rainfall rates, soil and geometrical characteristics of the plots. It can be seen that soil loss varies from nearly negligible values (20 g/m/yr) to unacceptably high levels (to over 4·7 kg/m/yr), according to the different types of land cultivation. Deep ploughing and heavy herbicide treatment give rise to accelerated erosion processes leading to soil losses much higher than in other vineyard plots in Europe.
Frost weathering and the saturation of coastal rocks
Authors: Trenhaile A. S. , Mercan D. W. 
Published: February 2007

AbstractMeasurements were made of the water content in coastal rocks, by simulating tidal oscillations in the laboratory, and by field measurement in eastern Canada. If rapid freezing takes place upon exposure to the air, saturation levels may be high enough to permit frost weathering in fine grained rocks in the lower portions of the intertidal zone. Near the high tidal level, however, it may be dependent upon a supply of water from the ice foot and from melting snow. If freezing is slow, frost action may be inhibited by desorption of the rocks while they are exposed by the ebb tide. There was no evidence of a level of permanent sea water saturation within the intertidal zone. Ambient temperature and humidity may affect the rate of rock desorption.
Diffusion models of slope development
Authors: Trofimov A. M. , Moskovkin V. M. 
Published: February 2007

AbstractThis paper represents a systematic investigation of slope evolution diffusion models and has the following sections: (1) The model of slope development with linear coefficient k = k0x; (2) The model of slope development with quadratic coefficient in x; (3) Slope development model with vertical lowering of base level (downcutting); (4) Slope development model with the base level a horizontal variable (undercutting); (5) Steady‐state regime of undercut slopes; (6) Model of a pediment and scree slope formation.The comparison is made between mathematical and classical methods of slope evolution analysis.
The influence of soil properties on the erodibility of Belgian loamy soils: A study based on rainfall simulation experiments
Authors: Verhaegen Th. 
Published: February 2007

AbstractTwenty soils from the Leuven region were tested in the laboratory with a rainfall simulator. Their texture varied from loam to loamy sand. On the basis of the results obtained, they were classified as a function of the runoff and splash erodibility. For every soil, several properties were determined and tentatively used to explain the classifications based on the runoff and splash erodibility.Significant negative correlations were found between silt content, aggregate stability, C5–10 index, water content at saturation, and cohesion on the one side and erodibility on the other; a positive correlation was found between sand content and erodibility.
Formation of afterflow silt loam deposits and structural modification due to drying under warm conditions: An experimental and micromorphological approach
Authors: Mücher H. J. , De Ploey J. 
Published: February 2007

AbstractIn earlier papers the authors discussed several micromorphological and textural characteristics of loamy afterflow deposits derived from loess material and formed during overland flow without splash. This discussion is completed by considering the critical load concentrations ccr for the start of sedimentation, taking into account the hydraulic properties of laminar flow. Furthermore, a remarkable combination of clayey and medium coarse, sandy laminae was observed in the deposits produced under laboratory conditions. Mechanisms are proposed to explain the affinity of these fractions for simultaneous deposition.When laminated silt loam deposits are found in the Pleniglacial Middle loess deposits in the southern part of The Netherlands or in the Belgian Hesbayan loess, showing structural modifications, for example cracks formed after sedimentation, it is not always clear whether these modifications were the results of cold or relatively warm conditions. This paper describes micromorphological and laboratory investigations aimed at identifying criteria representative of warm conditions. The experiments examined the effect of drying on the structure of laminated silt loam deposits produced by afterflow and enabled the characterization of the modifications formed.Drying could be done at room temperature, with circulating warm air, or at temperatures below 0°C. Elsewhere (see Coutard and Mücher, 1985), the influence of drying at temperatures below 0°C on the structures of an afterflow silt loam deposit will be discussed.In comparison with the deformation in laminated silt loam deposits due to freeze‐drying, these new formations are small and have only locally influenced the sedimentary structures. These structure modifications are:

formations of cracks dominantly in clay layers and less (about 25 per cent of the cracks) in very fine silt layers, consisting of grains smaller than 10 μm in diameter, with only very locally deformations of the laminated structure;
only incidentally the cracks are partly refilled by a subsequent overland flow deposit, mostly only followed by sealing of cracks;
only incidentally the cracks are partly refilled by a subsequent overland flow deposit, mostly only followed by sealing of cracks;
curling or argillaceous laminae, maximum 5 mm in upward direction;
only very locally, formations of the tiny waved laminae, with a vertical amplitude between 100 and 400 μm, in combination with the occurrence of vesicles.
The potential use of pollen in the identification of suspended sediment sources
Authors: Brown A. G. 
Published: February 2007

AbstractPollen and spores form a significant part of the suspended organic load of a New Forest stream. Flood concentrations reach 230 grains ml−1 while baseflow carries under one grain ml−1. Hydrographs from different seasons show differing hysteretic loops for pollen and spore concentrations against discharge and suspended sediment. These variations reflect not only factors of production, but the type and distance of the contributing sources. This investigation suggests that variations in flood pollen and spore concentrations may be used to trace such suspended sediment sources as: eroding bedrock, channel banks, or hillslopes under specific vegetation covers.