Pediment response to drainage basin evolution in south-central Arizona

Phillip H. Larson, Ronald Dorn, R. Evan Palmer, Zack Bowles, Emma Harrison, Scott Kelley, Mark Schmeeckle, John Douglass

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


The Sonoran Desert portion of the Basin and Range physiographic province contains a number of streams that now flow across once-closed basins. We explore here the research questions of if and how granitic rock pediments respond to the transition from rimming endorheic basins to bordering through-flowing streams. Granitic rock pediments of the northern Usery and eastern McDowell Mountains once graded to the closed Miocene-Pliocene Pemberton basin that occupied the present-day location of the confluence of the Salt and Verde Rivers. The process of lake overflow, which integrated these rivers, first aggraded fill terraces that, in turn, caused aggradation of a mantle of transported grus on bedrock pediments. Subsequent episodic incision of the Salt and Verde rivers lowered the base level; this led to the development of erosional features such as rolling topography of a degrading pediment mantle; exposure of the former piedmont angle and its associated zones of enhanced bedrock decay and regolith carbonate; and exposure of spheroidally weathered bedrock and emerging tors, some of which experienced 20th century erosion. The granitic pediments of the former Pemberton Basin, which now transport grus to the Salt and Verde rivers, have actively adjusted to aggradational and degradational events associated with drainage integration and do not appear to be inherited from an ancient wet climatic interval.

Original languageEnglish (US)
Pages (from-to)369-389
Number of pages21
JournalPhysical Geography
Issue number5
StatePublished - Sep 3 2014


  • Basin and Range
  • Sonoran Desert
  • carbonate
  • drainage basin evolution
  • fluvial terrace
  • granitic landscapes
  • landscape evolution
  • pediment

ASJC Scopus subject areas

  • General Environmental Science
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • General Earth and Planetary Sciences


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