Limits to Relief

Abstract

Comparison of slope profiles in areas exhibiting widespread bedrock landsliding with the use of a model for the maximum size of stable hillslopes established that mountain-scale material strength can limit topographic relief. Conventional laboratory values for intact rock greatly exceeded integrative rock strength properties that were back-calculated from the upper limit to hillslope relief and gradient in the northern Cascade Range and Santa Cruz Mountains. Back-calculated strength values, however, were indistinguishable from those obtained through field and conventional laboratory measurements on the weakest members of each rock formation, as well as on glacial sediments along the Cascade front. These results contrast with the conventional assumption that relief is incision-limited and indicate that the relief of mountain ranges can reflect landscape-scale material strength, as well as the interaction of tectonic and climatic processes.