bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lithologic control of bedrock meander dimensions in the appalachian valley and ridge province: A comment on a comment
Authors: Braun Duane D. 
Published: February 2007

AbstractAbrahams' comment relates meander length to channel cross‐section shape and recurrence interval so that meander length can be both directly and inversely proportional to rock resistance. This reply notes that either meander length is directly proportional to rock resistance or it is not; one cannot have it both ways. Many Appalachian Valley and Ridge bedrock meanders are shown to be the same size as alluvial meanders, and appear to be somewhat underfit. A hypothesis is proposed where modest discharge increases may have accelerated bedrock meander cutting although present streams remain capable of slowly cutting the meanders.
The significance of rainsplash in the surficial debris cascade of the colorado front range foothills
Authors: Morris Scott E. 
Published: February 2007

AbstractThe surficial characteristics and precipitation regime of sparsely vegetated hillslopes in the montane zone of the Colorado Front Range suggest that rainsplash may be an important component of the surficial debris cascade. Site sediment flux data from two study periods reveal marked spatial and temporal variability. Comparison of these date with sediment movement data from splashcups suggests the following conclusions: (1) Detachment rates of the rainsplash process appear great enough to account for the sediment flux in the open Gerlach‐type traps; (2) Areal extrapolation of rainsplash transport suggest that 88 per cent of the fine sediment flux in 1982 can be attributed to rainsplash; (3) Estimates of rainfall energy and changes in the potential energy of hillslopes by mass transport suggests a process efficiency of 0.05 per cent for rainsplash. If this procedure is applied to sediment flux values from open traps, the low precipitation‐energy cascade of 1982 appears to be largely rainsplash‐transported sediment. Extrapolation with the 1981 data suggests more aggressive overland flow erosion and transport.
Rates of erosion of till in the nearshore zone
Authors: Davidson‐Arnott Robin G. D. 
Published: February 2007

AbstractMeasurements of vertical erosion of till in water depths ranging from 1.1 m to 5 m have been obtained using a modified micro‐erosion meter. Measurements in this environment are hindered by poor underwater visibility and losses due to high erosion rates and ice action. There is considerable spatial and temporal variability in the erosion rates measured but average values show a general increase from 11 mm y−1 in 6 m of water to about 35 mm y−1 in 2.3 m of water and even higher rates closer to shore. The measured values in shallow water are in good agreement with long‐term rates extrapolated from shoreline recession. It is suggested that erosion occurs through abrasion and fluid stressing, and that these mechanisms are aided by softening of the upper surface of the till, possibly through cyclic ‘fatigue failure’.
Photo‐sieving: A method for grain‐size analysis of coarse‐grained, unconsolidated bedding surfaces
Authors: Ibbeken Hillert , Schleyer Ruprecht 
Published: February 2007

AbstractThe photo‐sieving method enables the grain‐size analysis of particles > 10 mm from unconsolidated openwork bedding surfaces. The accuracy is equal to the machine‐sieving method. The sediment surface is photographed in the field using a camera stand. The enlarged print is digitized for computer processing by tracing the outlines of the pebbles. From the size and shape of the projection area of the individual pebble images the computer determines the ellipsoids of revolution, classifies these ellipsoids, and establishes their grain‐size distribution in percentage by weight. Thus photo‐sieving differs distinctly from point‐counting techniques. With the aid of photo‐sieving, the surface grain‐size distributions of larger sedimentary systems may be regularly mapped. Alluvial fans, braided rivers, both onshore and offshore coasts or areas of relict sediments and manganese nodules are suitable for this method.
A re‐examination of the evidence for a plio‐pleistocene marine transgression on the Chiltern hills. I. structures and surfaces
Authors: Moffat A. J. , Catt J. A. , Webster R. , Brown E. H. 
Published: February 2007

AbstractBorehole and surface outcrop data are used to construct sub‐Chalk, sub‐Upper Chalk and sub‐Tertiary contour maps for the Chiltern area. The results show a southwest‐northeast monocline, which coincides with the change of slope at the lower boundary of the morphological bench on the Chalk dipslope that Wooldridge and Linton attributed to Plio‐Pleistocene marine erosion. Younger northwest‐southeast synclines coincide with the main transverse river valleys of the Chilterns. The monoclinal flexuring casts doubt on the value of the bench as evidence for a Plio‐Pleistocene transgression.
An indirect method of determining magnitudes of erosion using the c/p' ratio
Authors: Pitts John 
Published: February 2007

AbstractAn approximate method is described for determining the maximum consolidating pressure in a hard, heavily overconsolidated fissured clay. From this, the overburden thickness producing the observed degree of consolidation has been calculated. The normal method of calculating preconsolidation pressure using an oedometer was not possible. The ratio c/p' is used in conjunction with the undrained shear strength. Values of c/p' are determined using empirical relationships with Atterberg Limit values. The results allow an overburden thickness to be calculated by assuming a value for unit weight.
The permanence of stream networks in Britain: Further comments
Authors: Burt T. P. , Oldman J. C. 
Published: February 2007

AbstractPrevious surveys of the stream network in an area of blanket peat moorland in the Southern Pennines, England, are reassessed with reference to the publication of a new ordnance survey 1:10000 Metric Edition map for the area. It is concluded that a significant number of low order streams are still omitted on the new map, and that the use of field surveys remains essential in such heavily dissected terrain.
Debris from the basal ice of the Agassiz ice cap, Ellesmere Island, arctic Canada
Authors: Gemmell A. M. D. , Sharp M. J. , Sugden D. E. 
Published: February 2007

AbstractThis article describes the characteristics of debris obtained from the basal ice in a borehole in the Agassiz ice cap, Ellesmere Island, Northwest Territories by the Canadian Polar Continental Shelf Project in 1979. The debris appears to have been incorporated by basal freezing at a time when the base of the glacier upstream was near the pressure melting point and some 19°C warmer than at the present site. Such an occurrence may be explained by a different flow regime, by a thicker ice sheet, by the influence of irregular bedrock topography on basal ice conditions at some stage in the past, or by a combination of these factors.
Dynamics of bedload transport in Turkey brook, a coarse‐grained alluvial channel
Authors: Reid Ian , Frostick Lynne E. 
Published: February 2007

AbstractAutomatic and continuously recording samplers are deployed in a Hertfordshire gravel‐bed stream to show that bedload transport is related to stream power. The pattern is similar to that already established for North American channels but, because the record is so detailed, it is possible to identify the cause of the considerable scatter that is normal in such relationships. A major factor is the occurrence of rhythmic pulses in bedload discharge that are not matched by similar fluctuations in hydraulic variables. It is suggested that these pulses reflect downstream differences in the concentration of mobile particles in a slow‐moving traction carpet, and that they may be likened to kinematic waves. The record also reveals that the threshold of sediment transport—always presumed hithero to be associated with incipient motion—is related to the cessation of bedload transport in a river flood. Indeed, the mean value of stream power at the finish of bedload transport is only 20 percent of that prevailing at the moment of incipient sediment motion. Because of this, there is an inevitably poor correlation between actual bedload transport rates and those predicted by bedload equations which rely upon a single traction threshold. These new data show that the general inverse relationship between bedload discharge and water‐depth : grain‐size ratio proposed by Bagnold (1977, 1980) is not universal. Transport efficiency for this gravel‐bed stream is typically 0.05 per cent of available stream power, which compares with 1.6 per cent for a river moving both gravel and sand, and 5 per cent for another channel where bedload is composed predominantly of sand‐sized particles. It is argued that coarse and fine‐grained alluvial channels may need to be considered separately. By allowing for differences in traction threshold at the beginning and end of bedload events, and by averaging bedload discharge flood by flood in order to smooth out the effect of pulses, it is possible to achieve a reasonably good prediction of average bedload transport rate in terms of stream power.
A re‐examination of the evidence for a Plio‐Pleistocene marine transgression on the Chiltern Hills. II. drainage patterns
Authors: Moffat A. J. , Catt J. A. 
Published: February 2007

AbstractThe dry valley pattern of the Chiltern Hills is divided into 55 third order drainage basins which are grouped morphometrically into five groups. The character and distribution of the groups are determined mainly by the lithology of surface deposits and the structure of the underlying Chalk. No evidence has been found for different drainage patterns on the parts of the dipslope equivalent to the ‘Mio‐Pliocene peneplain’ and ‘Plio‐Pleistocene marine platform’ of Wooldridge and Linton (1955), nor for superimposition of drainage from covers of Plio‐Pleistocene or Palaeogene sediments.
Rilling of hillslopes reclaimed before 1977 surface mining law, Dave Johnston Mine, Wyoming
Authors: Soulliere Edward J. , Toy Terrence J. 
Published: February 2007

AbstractThe erosion of hillslopes reclaimed following the surface‐mining of coal is an important geomorphologic concern. However, progress in the design of post‐mining topography and its hydrologic response has been hampered by the paucity of research focusing on the propensity of rill formation on these disturbed surfaces. This investigation is intended to partially rectify this situation through the development of regression equations for the prediction of rill frequency and magnitude based upon site characteristics. Rill width can be estimated using soil bulk density, hillslope age, and hillslope length with a standard error of 0.152 log10 units at this location. Rill depth can be estimated using soil shear strength, hillslope length, and hillslope age with a standard error of 0.114 log10 units. Rill length can be estimated using hillslope length, percent silt in the soil, hillslope age, Bouyoucos Clay Ratio, and soil bulk density with a standard error of 3.515 m. Rill frequency can be estimated using soil bulk density, Bouyoucos Clay Ratio, soil compaction, soil reaction (pH), and hillslope age with a standard error of 0.241 rills/m. The cross‐product of rill width times depth can be estimated using soil shear strength, hillslope length, hillslope age, and soil bulk density with a standard error of 0.260 log10 units. These results must be tested further under various environmental conditions. Nevertheless, prediction of rill formation seems to be a problem capable of solution.
Flow variability and the bankfull depth of sand‐bed streams of the American midwest
Authors: Pizzuto James E. 
Published: February 2007

AbstractThe bankfull depths of 15 midwestern sand‐bed streams increase with increasing variability of flow. Depths are also well represented by a simple one‐dimensional model of vertical floodplain accretion. Thus, the correlation between depth and flow variability may be explained by the ability of deep, sediment‐laden flows to construct high floodplains.Bankfull depths are also strongly correlated with the average annual maximum flow. Apparently, the average annual maximum flow adequately represents the cumulative influence of varying flows on rivers studied here. These observations further validate the concept of a dominant channel‐forming discharge of moderate return frequency in humid temperate climates.
Sedimentation patterns in a gulf coast backbarrier marsh: Response to increasing submergence
Authors: Delaune R. D. , Smith C. J. , Patrick W. H. 
Published: February 2007

AbstractThe rate of vertical accretion was determined on two backbarrier marshes in the Mississippi River Plain, using 137Cs dating techniques. An average accretion rate of 0‐55 cm yr−1 was found on Grande Terre, and 0.78 cm yr−1 on Grand Isle. Analysis of mineral organic content of the marsh profile shows that the backbarrier marshes accrete through (1) accumulation of low density organic matter, and (2) episodic deposition of high density mineral sediment probably associated with major hurricanes or storm events. The rates of vertical accretion were two to three times less than the rate of submergence due primarily to rapid subsidence in the deltaic plain, and imply that these backbarrier marshes will progressively deteriorate.
Cave sedimentation in the new Guinea highlands
Authors: Gillieson David 
Published: February 2007

AbstractThis paper investigates the nature and processes of sedimentation of allogenic cave deposits in the high relief, everwet karsts of montane New Guinea. Under the high intensity rainfall regime, episodic mass movements in small karst catchments provide a wide range of sediment textures from clayey gravels to fine clays. These allogenic sediments are deposited into pools of water within the caves, giving sedimentary structures analogous to turbidites. Diamictons within the cave relate to episodic mudflows in the catchment. These deposits move as fluidized masses in a manner similar to some esker deposits. Cross‐stratified sediments are formed by dumping of pulses of sediment laden water into deep pools. Extremely fine‐grained clays and muds accrete parallel to underlying surfaces following flood pulses. These deposits represent the last phase of catchment instability, when a small amount of slopewash occurs. Catchment processes are dominated by solution and episodic mass movements. When the thick root mat which masks the ground is disrupted, some slopewash occurs but it is not a major component in catchment processes.
The headward extent of fluvial landforms and associated vegetation on massanutten mountain, Virginia
Authors: Hupp Cliff R. 
Published: February 2007

AbstractVariation in fluvial landforms and associated vegetation in the headward (upstream) direction has received little study and the controlling factors are not well understood. The relations among channel gradient, basin area, stream order, and the headward extent of fluvial landforms and vegetation was studied in 18 small basins and larger nearby stream reaches in the Massanutten Mountain area, northern Shenandoah Valley, Virginia. Low‐order streams were traversed to their basin heads. Notice was made of the point or region of the disappearance of fluvial landforms. Indicator species were used to confirm landform identification. The studied landforms include the channel bar, channel shelf, floodplain, and terraces. Basin geomorphic characteristics were determined from topographic and geologic maps and ground surveys. Results suggest that gradient is the most important factor controlling the development of fluvial landforms. Floodplains have not developed along stream reaches where average channel gradients exceed 0.15. Channel shelves and associated vegetation occur farther upstream than floodplains.
Interception, drop size distributions and rainfall kinetic energy in four colombian forest ecosystems
Authors: Vis M. 
Published: February 2007

AbstractInterception losses, rain and throughfall drop size spectra and kinetic energy were studied in four relatively undisturbed tropical forest ecosystems along a transect across the Central Andean Cordillera of Colombia at altitudes between 3000 and 1000 m above sea level. Interception amounts ranged from 11 to more than 20 per cent of the total rainfall and fell within the normal range of interception figures observed in natural tropical forests.Drop size spectra were established using the filter paper method; the drop size distributions of the open field rainfall were unimodal while the throughfall had bimodal distributions, with a higher percentage of the volume of rain falling as large drops.Disturbance of the natural forests, for example by logging activities or cattle grazing, will further increase the throughfall kinetic energy and may lead to higher splash erosion rates inside the forests than in the open field.The kinetic energy of the throughfall was higher than that of the open field rainfall (20‐70 per cent), even after correcting for interception losses (4‐30 per cent). Splash‐cup experiments, conducted both in the field and in the laboratory, indicated that the kinetic energy is a good index of rainfall erosivity. Inside the forests the amounts of sand splashed from the splash‐cups was, after correction for interception losses, 2‐16 per cent higher than outside the forests.
Secondary flows and the pool‐riffle unit: A case study of the processes of meander development
Authors: Thompson Alan 
Published: February 2007

AbstractThe major bedforms of gravel bed rivers, whether braided, meandering or straight, may be usefully resolved into pool‐riffle units, each comprising a single scour pool together with an associated depositional shoal downstream. At low flow, the latter may be characterized by a single emergent bar‐head and submerged riffle, or by a variety of remnant braid bars, depending upon the type of channel.Identification of pool‐riffle units and observation of associated flow structures on a small meandering stream in northwest England has demonstrated important links between bedforms, flow patterns and channel change.Each unit appears to be associated with a systematic pattern of secondary flows, which are able to modify the bedforms and initiate meander development. Feedback links between plan morphology, flow patterns and erosive and depositional forces within these units ensure that each stage of meander growth has a characteristic style of channel change. Consequently, meanders tend to evolve by regular cycles of increasing curvature and complexity.
Reply to—comparison of taxon calibrations, modern analogue techniques, and forest‐stand simulation models for the quantitative reconstruction of past vegetation a critique by A. M. Solomon
Authors: Delcourt Hazel R. , Delcourt Paul A. 
Published: February 2007

AbstractThree points raised by Solomon's discussion are clarified, a conservative approach is preferred, using pollen‐vegetation relationships based on all taxa potentially involved for a given site. The use of techniques for comparison with modern analogues is defended, provided that appropriate methods such as Standardized Euclidian Distance are used. The model ‚FORET’︁ used by Solomon is based on half hectare plots and is not considered ideal for aggregation to the forty hectare lake site or to the same area for pollen grains entering it.
Towards the use of catchment geomorphology in flood frequency predictions
Authors: Beven Keith 
Published: February 2007

AbstractA further development of a topography‐based model of catchment hydrology (TOPMODEL) is described and applied to the problem of predicting flood frequency characteristics. The model can simulate infiltration excess, saturation excess, and subsurface runoff contributions to peak flows. Catchment geomorphology plays a central role in predicting the nature of the hydrological response. Using stochastic rainfall and initial condition inputs based on measured data, the model satisfactorily reproduces the mean hourly flow flood frequency growth curve for the Wye catchment, but not the mean number of peaks greater than 3mm h−1 each year. Suggestions for further improvements are made.
The physical properties of quartz‐micaschist and their application to freeze‐thaw weathering studies in the maritime antarctic
Authors: Hall Kevin 
Published: February 2007

AbstractAs part of a study on freeze‐thaw weathering in the maritime Antarctic an investigation was made of the physical properties of the local rock. Tests were made of point‐load compressive strength, Schmidt hammer in situ rock strength, moisture content, indentor resistance and the size range of weathering products. The resulting data were used to consider the form of freeze‐thaw weathering operative in the field and its relationship to laboratory simulations. A distinct difference between ‘massive rock’ and ‘intact rock’ is observed in the field. It is suggested that future studies should generate a greater database pertaining to rock properties as it is an invaluable aid in the study of mechanical weathering.
A study of channel changes in a reach of the North Nashwaaksis stream, New Brunswick, Canada
Authors: Bray Dale I. 
Published: February 2007

AbstractRepeated surveys of a short channelized reach of the North Nashwaaksis Stream near Fredericton, N.B. over the period 1971‐1981 provide the basis for evaluating the type and magnitude of some physical and botanical changes in the study reach.In 1967 a 200 m reach of the stream was shortened by about 10 per cent by cutting a new channel through a pasture. The original channel was protected by a dense growth of shrubs along its banks.The average width of the top of the channel in the channelized reach widened from 11 m to 17 m in response to a major flood in 1973. Rough estimates indicate that as much as 78 per cent of the published suspended‐sediment load associated with the flood could reasonably have been derived from the banks in this short channelized reach.During the 1973 flood, a mid‐channel bar was formed in the portion of the channel which experienced the most widening. Subsequent to the flood, the mid‐channel bar was first colonized by sedges, and then by alders. By 1981, the width of the low flow channel in the channelized reach was about the same as that for the unmodified upstream reaches.This case study provides useful information for those planning channelization projects on small to intermediate size streams in humid temperate areas.
The use of small flumes for the determination of soil erodibility
Authors: Verhaegen Th. 
Published: February 2007

AbstractThe objective of this study was to examine the possibility of determining soil erodibility of loamy soils with small flumes. This was done by comparing the classification of soil erodibility obtained in the field with that obtained in the laboratory. Therefore twenty soils with a texture varying from silty loam to sandy loam were selected from the Leuven region. The erosion in the field was determined by measuring the volumetric evolution of the rill pattern. In the laboratory the soils were tested with a rainfall simulator and small flumes.The conclusion was that for loamy soils the flume experiments are a quick, simple, and reliable method for the determination of the relative soil erodibility.
Effects of time under rain, sampling technique and transport of samples on size distributions of water‐stable aggregates
Authors: Cleary J. L. , Loch R. J. , Thomas E. C. 
Published: February 2007

AbstractTwo methods for sampling aggregates in the soil surface under simulated rain were compared using two soil types. Results showed that aggregate size distributions obtained by spatula sampling were not significantly different from those obtained using rings buried in the soil surface, provided both were sampled to the same depth. The effect of transporting samples over a distance of 60 km was non‐significant when samples were placed in bottles half‐filled with rainwater and transported in an upright position. The per cent aggregates > 0.125 mm was found to be the most suitable index of aggregate stability for both soils.