Speculations Concerning Paleohydrologic Controls of Terrestrial Sedimentation

Abstract

Research Article| November 01, 1968 Speculations Concerning Paleohydrologic Controls of Terrestrial Sedimentation S. A SCHUMM S. A SCHUMM Department of Geology, Colorado State University, Fort Collins, Colorado Search for other works by this author on: GSW Google Scholar GSA Bulletin (1968) 79 (11): 1573–1588. https://doi.org/10.1130/0016-7606(1968)79[1573:SCPCOT]2.0.CO;2 Article history received: 14 Feb 1968 rev-recd: 24 May 1968 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation S. A SCHUMM; Speculations Concerning Paleohydrologic Controls of Terrestrial Sedimentation. GSA Bulletin 1968;; 79 (11): 1573–1588. doi: https://doi.org/10.1130/0016-7606(1968)79[1573:SCPCOT]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The relations that have been recorded among modern climatic, phytologic, and hydrologic data are used to speculate about the effects of evolving vegetation on the hydrologic cycle. At present the peak of erosion rates occurs in semiarid regions, whereas during prevegetation time erosion rates rose to a plateau, the magnitude of which depended upon the erodibility and weathering characteristics of the rocks. With the appearance of terrestrial vegetation and its colonization of the earth's surface, erosion rates decreased, as did runoff and flood peaks.A review of the relations existing between the morphologic and hydrologic characteristics of river channels demonstrates that fluvial sedimentary deposits are significantly different depending upon the nature of the sediment load moved through the channel.Combining the conclusions obtained from an analysis of hydrologic relations with conclusions concerning effects of type of sediment load upon river morphology, it is possible to speculate on the changing nature of the land phase of the hydrologic cycle before and during the colonization of the landscape by vegetation.During prevegetation time, bed-load channels moved coarse sediments from their sources and spread them as sheets on piedmont areas. With increased plant cover, alluvial deposits were stabilized, but large floods caused periodic flushing of sediment from the system, thereby creating cyclic sedimentary deposits.The influence of climate change on the volume and type of sediment moved from an erosional system became more pronounced as the effect of vegetation on the hydrologic cycle increased. Finally, with the appearance of grasses during the Cenozoic Era, the relations between climate, vegetation, erosion, and runoff became much as today except for the influence of man. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.