摘要:

AbstractThe paper looks at the process of lateral translocation in a small valley basin from the Northaw Great Wood, Hertfordshire. The valley basin comprises four lithostratigraphic units (London Clay and Pebble Gravel, and the others a mixture of these two), which were initially established in the field by a rough assessment of texture. Particle size analysis validated the lithostratigraphic units as delineated in the field; it was found unnecessary to alter the boundaries of the units. Patterns of lateral translocation of silt and clay (measured by the hydrometer method) and the amorphous colloidal hydrous oxides and hydroxides of Al, Fe, Mn and Si (measured in oxalate solution by atomic absorption spectrophotometry) are inferred from balance sheets of the relative gains and losses of the materials. Materials from horizons formed in lithostratigraphic units derived from London Clay are balanced against a clay dilution factor; those from the lithostratigraphic unit of Pebble Gravel against the dilution of sand on a clay‐free basis. The results lead to the following conclusions about the process of lateral translocation: it has been a significant contributor to soil development; larger amounts of material have moved down‐slope towards the hollow than over the nose because there has, theoretically, been more throughflow in the hollow; for some materials there has been less down‐slope transport in lower horizons owing to less throughflow in

ISSN:0360-1269    

DOI:10.1002/esp.3290010202

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractAn area of shallow karst depressions in St. Ann parish, Jamaica is examined. Shallow, ‘temperate’ forms such as these are common in tropical karst areas.Depressions are analyzed morphometrically and a considerable degree of structural control appears to be exhibited. Some morphometric parameters, in particular the depth/diameter ratio, which have been used to postulate depression origin, are examined.Depression hydrology is investigated. Depressions appear to exhibit characteristics of small drainage basins. The occurrence of sporadic flood events is suggested as an important element in the development of surface channel networks. The integration of the depressions into the regional drainage system is investigated by water tracing of ‘underground flow sections’.Chemical analysis of waters in various parts of the drainage system reveals variations which point to the importance of solutional activity at the soil‐bedrock interface. The influence of a soil cover in promoting solutional activity is

ISSN:0360-1269    

DOI:10.1002/esp.3290010203

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThis paper constructs a model of channel geometry composed of three subsections: a steady‐state submodel, a gradedstate submodel, and a stochastic error submodel. With the aid of this representation of the morphology of channels, the at‐a‐point changes in geometry can be reproduced by a simple recursive equation of autoregressive, moving‐average form which is derived from methods used in the statistical analysis of time series. A set of height loss data for three Japanese rivers derived from Yatsu's (1955) paper is used to determine the effect of bed material changes on adaptations within the graded‐state submodel of the channel. The results of analyzing the autocorrelation function, spectrum, and adaptive parameter shifts within this model can be used to infer that significant changes in the amplitude of height change variation, and a shift to higher frequency oscillations of bed forms are associated with the shift in bed material c

ISSN:0360-1269    

DOI:10.1002/esp.3290010204

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe Hortonian model of runoff flow which had been thought to be applicable in arid areas has previously been shown not to be valid, notably in Israel, where inverse relations have been observed between slope angle, and runoff discharge and slope erosion. The paper discusses laboratory experiments on simulated slope conditions in a rather arid environment. It is shown by rain simulation on granite grus that infiltration capacity is a function of rainfall intensity, slope angle and runoff discharge. The infiltration capacityfcan equal the rainfall intensity beyond a critical distancex(m)so that discharge becomes constant. Debris covers affect runoff hydraulics, especially on poorly cohesive soils, and both slow downslope and upslope movements which correspond to the process of so‐called runoff creep can occur. Coarse debris and grass covers, as roughness factors, induce hydraulic discontinuities and activate local turbulent flow and slope erosion. Instead of being merely protective elements these factors tend to catalyze the slope wash, in comparison with naked surfaces, if the Reynolds number of the flow exceeds a certain critical valu

ISSN:0360-1269    

DOI:10.1002/esp.3290010205

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe formation of. and landsliding in extremely sensitive postglacial clay soils (quickclays). could be affected by certain factors including mineralogical composition, interparticle bond type, soil structure, leaching, cementation and particle coatings. Factors which should be taken into account during related investigations include nomenclature and size limits, model soils, distribution, rheology, scientific status, local earthquake intensity and frequency. Landsliding in quickclays occurs largely by means of catastrophic flowslides. These are due to the predominance of short range bonds in the soil system. The short range bonds ensure a very low plasticity index (of the order of 10 or below) and may be due to the inherent nature of the material or to post‐depositional events. Mineralogical studies suggest that the former is more critical although cementation plays a major role in Canadian quickclays. The Yatsu philosophy of material investigation should be applied to quickclays on a larger scale: landsliding and slope evolution are ultimately controlled by the forces operating (or not operating) between two adjacent soil particles. A particular set of tectonic, glacial and sedimentological circumstances are required for quickclay formation; the correct combination rarely occurs which accounts for the very limited occurrence of clay soils with sensitivities of greater than 10

ISSN:0360-1269    

DOI:10.1002/esp.3290010206

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe Black Mountain Scarp in Carmarthenshire is currently being modified by debris‐flow activity along gullies cut into the vegetated scree, which is a persistent feature of the scarp‐front. Low angled, concave debris flow cones are accumulating at the mouths of the gullies.Mean rate of sediment yield from the sides of one gully was estimated to be 8·4 m3in one year, and 9·8 m3was shifted out of the gully by a single debris‐flow in the same year. Movement by other transport processes, such as streamflow, was negligible in the gullies. No new gullies are being initiated at the present and all of them appear to be in a similar state of development. Consequently, it appears that some marked environmental change was responsible for initiating gully erosion. If present rates of gully‐erosion are representative of the past, the gullies are only about 540–700 years old and may possibly have been initiated by sheep‐grazin

ISSN:0360-1269    

DOI:10.1002/esp.3290010207

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractSoil mapping and soil profile studies on the Chalk of south‐east England outline the distribution and origin of superficial deposits more clearly than hitherto, and do not support the widely accepted history of landscape development proposed by Wooldridge and Linton (1955). Deposits formed by weathering and periglacial disturbance of a thin cover of basal Tertiary deposits occur on all parts of the dip‐slope interfluves, suggesting that the exhumed sub‐Tertiary surface, somewhat lowered by dissolution of the Chalk, is much more extensive than supposed by Wooldridge and Linton. The evidence for high Plio‐Pleistocene sea levels is reviewed, with particular reference to their limited effect on soils and superficial deposits and on the morphology of the dip‐slope. Alternative explanations for the so‐called Calabrian marine platform and cliff are considered. Emphasis is placed on periglacial processes in the later Pleistocene denudation of the Chalk, and on the protective role played by the cover of disturbed basal Tertia

ISSN:0360-1269    

DOI:10.1002/esp.3290010208

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

ISSN:0360-1269    

DOI:10.1002/esp.3290010201

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY