Soil production on a retreating escarpment in southeastern Australia

Arjun Heimsath, J. Chappell, W. E. Dietrich, K. Nishiizumi, R. C. Finkel

Research output: Contribution to journalArticle

199 Citations (Scopus)

Abstract

The functional dependence of bedrock conversion to soil on the overlying soil depth (the soil production function) has been widely recognized as essential to understanding landscape evolution, but was quantified only recently. Here we report soil production rates for the first time at the base of a retreating escarpment, on the soil-mantled hilly slopes in the upper Bega Valley, southeastern Australia. Concentrations of 10Be and 26Al in bedrock from the base of the soil column show that soil production rates decline exponentially with increasing soil depth. These data define a soil production function with a maximum soil production rate of 53 m/m.y. under no soil mantle and a minimum of 7 m/m.y. under 100 cm of soil, thus constraining landscape evolution rates subsequent to escarpment retreat. The form of this function is supported by an inverse linear relationship between topographic curvature and soil depth that also suggests that simple creep does not adequately characterize the hillslope processes. Spatial variation of soil production shows a landscape out of dynamic equilibrium, possibly in response to the propagation of the escarpment through the field area within the past few million years. In addition, we present a method that tests the assumption of locally constant soil depth and lowering rates using concentrations of 10Be and 26Al on the surfaces of emergent tors.

Original languageEnglish (US)
Pages (from-to)787-790
Number of pages4
JournalGeology
Volume28
Issue number9
DOIs
StatePublished - 2000
Externally publishedYes

Fingerprint

escarpment
soil
soil depth
landscape evolution
bedrock
soil column
hillslope
creep
curvature
spatial variation
rate
mantle
valley

Keywords

  • Cosmogenic nuclides
  • Erosion
  • Geomorphology
  • Landscape evolution
  • Tors

ASJC Scopus subject areas

  • Geology

Cite this

Soil production on a retreating escarpment in southeastern Australia. / Heimsath, Arjun; Chappell, J.; Dietrich, W. E.; Nishiizumi, K.; Finkel, R. C.

In: Geology, Vol. 28, No. 9, 2000, p. 787-790.

Research output: Contribution to journalArticle

Heimsath, Arjun ; Chappell, J. ; Dietrich, W. E. ; Nishiizumi, K. ; Finkel, R. C. / Soil production on a retreating escarpment in southeastern Australia. In: Geology. 2000 ; Vol. 28, No. 9. pp. 787-790.
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