Some observations on the chemical weathering of the Dartmoor granite

Williams, Andy; Ternan, Les; Kent, M.

doi:10.1002/esp.3290110510

Cited by 27 publications

(16 citation statements)

References 33 publications

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“…1 and 2), similar to bedrock tors in other saprolitic granite landscapes described by Linton (1955), Twidale (1985), and Williams et al (1986). The weathered nature of the soil-mantled saprolite is exposed in local road-cuts, which also reveal granite core-stones, some of which are likely to emerge in the future as tors.…”

Section: Field Sitesupporting

confidence: 55%

Late Quaternary erosion in southeastern Australia: a field example using cosmogenic nuclides

Heimsath

Chappell

Dietrich

et al. 2001

Quaternary International

176

180

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Late Quaternary rates of apparent soil production, bedrock incision, and average erosion are determined for the southeastern highlands of Australia using in situ produced cosmogenic nuclide concentrations of 10 Be and 26 Al. Apparent soil production rates define a steep, inverse exponential function of soil depth with a maximum of 143 m Ma À1 under zero soil depth. There were no observed soil depths between about 25 cm and zero, however, such that the maximum observed rate is about 50 m Ma À1. The Bredbo River catchment average erosion rate is 1571 m Ma À1 , and is similar to the average hillslope erosion rate of 1671 m Ma À1 . Bedrock incision rates average 9 m Ma À1 and suggest that the higher rates of hillslope erosion may be in response to a pulse of incision, perhaps generated by knickpoint propagation. Bedrock erosion rates inferred from a tor profile average 3.8 m Ma À1 , with higher rates on other, more weathered tor tops. An aboveground tor profile of nuclide concentrations is consistent with a simple model of rapid stripping of the surrounding saprolite, supporting the view that at least one episodic period of increased denudation has affected the landscape evolution of the highlands. We test this hypothesis by using a simple landscape evolution model to reasonably predict the spatial variation of soil depth as well as the emergence of tors. r

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Section: Field Sitesupporting

confidence: 55%

Late Quaternary erosion in southeastern Australia: a field example using cosmogenic nuclides

Heimsath

Chappell

Dietrich

et al. 2001

Quaternary International

176

180

View full text Add to dashboard Cite

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“…Similar arguments could be advanced for the limited contribution of overland flow from variable source areas: e.g. silica, when used as a geochemical tracer, displays minimal dilution, confirming that the stormwater is dominated by 'old' water (Williams, et al, 1986).…”

Section: Geochemical Signalmentioning

confidence: 87%

A new interpretation of kinematic stormflow generation

Williams

Dowd

Meyles

2002

Hydrological Processes

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Abstract:The paper reviews a number of possible fast and slow hydrological flow mechanisms to account for rapid runoff generation within a catchment. A new interpretation of the kinematic wave process is proposed which develops some of these concepts to explain rapid subsurface flow from a watershed. Evidence for the process is provided by the results from a laboratory soil core experiment and an investigation of the hydrology of a Dartmoor hillslope. A tension response was monitored in the soil core in which pressure waves were propagated downwards and expelled water from the base. The transmission of the wave down the core was considerably faster than the movement of a chloride tracer. The concept of this kinematic wave process and associated water flux was then extended to the Dartmoor watershed. Raindrops reaching the wet soil surface caused pressure waves to travel laterally downslope. During large rainstorms, the hillslope became hydrologically highly connected and the pressure waves forced existing water from seepage faces into the saturated area adjacent to the stream, contributing substantially to the stream discharge. A kinematic contributing area was defined, as determined by both rainfall-runoff ratios and geostatistical analyses of hillslope soil moisture contents, which extended over at least 65% of the catchment area. This kinematic wave theory is consistent with results of translatory flow and macropore flow models, and stable isotope field studies of 'old/new' water.

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“…Mast & Drever 1990;Paces 1986;Williams et al 1986). The bedrock, glacial till, and soils of the HBEF contain Z-5% K (as K,O), similar to average crustal values (Johnson et al 1968).…”

Section: Supply Of K From Weathering and Cation Exchangementioning

confidence: 98%

The biogeochemistry of potassium at Hubbard Brook

et al. 1994

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Abstract. A synthesis of the biogeochemistry of K was conducted during in the reference and human-manipulated watershed-ecosystems of the Hubbard Brook Experimental Forest (HBEF), NH. Results showed that during the first two years of the study , which coincided with a drought period, the reference watershed was a net sink for atmospheric inputs of K. During the remaining years, this watershed has been a net source of K for downstream ecosystems. There have been long-term declines in volume-weighted concentration and flux of K at the HBEF; however, this pattern appears to be controlled by the relatively large inputs during the initial drought years. Net ecosystem loss (atmospheric deposition minus stream outflow) showed an increasing trend of net loss, peaking during the mid-1970s and declining thereafter. This pattern of net K loss coincides with trends in the drainage efflux of SO: and NO;, indicating that concentrations of strong acid anions may be important controls of dissolved K loss from the site. There were no long-term trends in streamwater concentration or flux of K. A distinct pattern in pools and fluxes of K was evident based on biotic controls in the upper ecosystem strata (canopy, boles, forest floor) and abiotic controls in lower strata of the ecosystem (mineral soil, glacial till). This biological control was manifested through higher concentrations and fluxes of K in vegetation, aboveground litter, throughfall and forest floor pools and soil water in the northern hardwood vegetation within the lower reaches of the watershedecosystem, when compared with patterns in the high-elevation spruce-fir zone. Abiotic control mechanisms were evident through longitudinal variations in soil cation exchange capacity (related to soil organic matter) and soil/till depth, and temporal and disturbance-related variations in inputs of strong-acid anions. Marked differences in the K cycle were evident at the HBEF for the periods 1964-69 and 1987-92. These changes included decreases in biomass storage, net mineralization and throughfall fluxes and increased resorption in the latter period. These patterns seem to reflect an ecosystem response to decreasing rates of biomass accretion during the study. Clearcutting disturbance resulted in large losses of K in stream water and from the removal of harvest products. Stream losses occur from release from slash, decomposition of soil organic matter and displacement from cation exchange sites. Elevated concentrations of K persist in stream water for many years after clearcutting. Of the major elements, K shows the slowest recovery from clearcutting disturbance.

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Some observations on the chemical weathering of the Dartmoor granite

Cited by 27 publications

References 33 publications

Late Quaternary erosion in southeastern Australia: a field example using cosmogenic nuclides

Late Quaternary erosion in southeastern Australia: a field example using cosmogenic nuclides

A new interpretation of kinematic stormflow generation

The biogeochemistry of potassium at Hubbard Brook

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