Landscape form and millennial erosion rates in the San Gabriel Mountains, CA

Roman A. DiBiase, Kelin Whipple, Arjun Heimsath, William B. Ouimet

Research output: Contribution to journalArticle

235 Citations (Scopus)

Abstract

It has been long hypothesized that topography, as well as climate and rock strength, exert first order controls on erosion rates. Here we use detrital cosmogenic 10Be from 50 basins, ranging in size from 1 to 150 km2, to measure millennial erosion rates across the San Gabriel Mountains in southern California, where a strong E-W gradient in relief compared to weak variation in precipitation and lithology allow us to isolate the relationship between topographic form and erosion rate. Our erosion rates range from 35 to 1100 m/Ma, and generally agree with both decadal sediment fluxes and long term exhumation rates inferred from low temperature thermochronometry. Catchment-mean hillslope angle increases with erosion rate until ∼ 300 m/Ma, at which point slopes become invariant with erosion rate. Although this sort of relation has been offered as support for non-linear models of soil transport, we use 1-D analytical hillslope profiles derived from existing soil transport laws to show that a model with soil flux linear in slope, but including a slope stability threshold, is indistinguishable from a non-linear law within the scatter of our data. Catchment-mean normalized channel steepness index increases monotonically, though non-linearly, with erosion rate throughout the San Gabriel Mountains, even where catchment-mean hillslope angles have reached a threshold. This non-linearity can be mostly accounted for by a stochastic threshold incision model, though additional factors likely contribute to the observed relationship between channel steepness and erosion rate. These findings substantiate the claim that the normalized channel steepness index is an important topographic metric in active ranges.

Original languageEnglish (US)
Pages (from-to)134-144
Number of pages11
JournalEarth and Planetary Science Letters
Volume289
Issue number1-2
DOIs
StatePublished - Jan 15 2010

Fingerprint

erosion rate
mountains
erosion
Erosion
mountain
slopes
hillslope
Catchments
soils
catchment
Soils
thresholds
Fluxes
Slope stability
Lithology
soil
Southern California
slope stability
lithology
exhumation

Keywords

  • cosmogenic radionuclides
  • erosion
  • landscape evolution
  • San Gabriel Mountains
  • topographic metrics

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Cite this

Landscape form and millennial erosion rates in the San Gabriel Mountains, CA. / DiBiase, Roman A.; Whipple, Kelin; Heimsath, Arjun; Ouimet, William B.

In: Earth and Planetary Science Letters, Vol. 289, No. 1-2, 15.01.2010, p. 134-144.

Research output: Contribution to journalArticle

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