LIMITS TO RELIEF

Comparison of slope profiles in areas exhibiting widespread bedrock la ndsliding With the use of a model for the maximum size of stable hills lopes established that mountain-scale material strength can limit topo graphic relief. Conventional laboratory values for intact rock greatly exceeded integrative rock strength properties that were back-calculat ed from the upper limit to hillslope relief and gradient in the northe rn Cascade Range and Santa Cruz Mountains. Back-calculated strength va lues, however, were indistinguishable from those obtained through fiel d and conventional laboratory measurements on the weakest members of e ach rock formation, as well as on glacial sediments along the Cascade front. These results contrast with the conventional assumption that re lief is incision-limited and indicate that the relief of mountain rang es can reflect landscape-scale material strength, as well as the inter action of tectonic and climatic processes.