Year: 1963
Type: report
Abstract: Denudation rates are calculated for drainage basins, which average 1,500 square miles in area and which are underlain predominantly by sedimentary and metamorphic rocks.Average denudation rates range from 0.1 to 0.3 feet per 1,000 years, whereas, an average of maximum denudation rates is about 3 feet per 1,000 years.Denudation rates are an exponential function of drainage-basin relief, indicating that denudation rates increase rapidly with uplift.Modern rates of orogeny are about 25 feet per 1,000 years, or about eight times greater than the average maximum denudar tion rate.As a result of this disparity between rates of orogeny and denudation, it is concluded that hillslope form is more a function of the difference between the rates of hillslope erosion and stream incision than of rates of uplift.This difference also makes it unlikely that a balance between rates of uplift and denudation will yield time-independent landforms.Calculations of the time required for planation of 5,000 feet of relief suggest that ample time exists between orogenic periods for the development of peneplains.Rapid orogeny accompanied and followed by relatively slower denudation should cause epicycles of recurrent uplift owing to isostatic adjustment to denudation.These phases of recurrent uplift after the cessation of tectonism may partly explain the existence of multiple erosion surfaces and terraces as well as the isostatic anomalies associated with old mountain ranges.
Source: USGS professional paper
DOI: 10.3133/pp454h
Author: Stanley Alfred Schumm
Language: English
Subfield: Earth-Surface Processes
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2157166061