Late Quaternary geomorphic evolution of the Colorado River, Bastrop and Fayette counties, Texas

dc.contributor.advisorBaker, Victor R.
dc.creatorLooney, Robert Michael
dc.date.accessioned2022-06-28T23:05:25Z
dc.date.available2022-06-28T23:05:25Z
dc.date.issued1977
dc.description.abstractAncient and modern flood plain and channel morphology was mapped in the late Quaternary alluvial valley of the Colorado River between Utley and La Grange, Texas. The analysis of N.A.S.A.-generated color aerial infrared photography, SKYLAB remote sensing imagery, and aerial panchromatic photography revealed nine assemblages of fluvial channel patterns. The paleochannels occur on multiple flood plain and terrace levels and are associated with deposits with variable textures, sedimentary structures, and lithologic composition. Quantitative geomorphic analysis showed that bankfull width for the late Quaternary Colorado River varied from 450 m to 200 m, meander wavelength from 575 m to 1730 m, and sinuosity from 1.3 to 3.6. The channel adjustments from low sinuosity to high sinuosity streams was accompanied by a decrease in meander wavelength and bankfull width. Sedimentological analyses show corresponding changes in grain size from sand and gravel to sand and silt transporting streams. The nine channel assemblages of the Colorado River reflect changes in runoff and sediment load characteristics from upstream catchment areas. These runoff and sediment load changes correlate with an alternating arid-humid climate in central Texas during the late Quaternary. The resulting hypothesis is that channel 7 is pre-Wisconsinan; channels 6, 6A, and 6B are Wisconsinan; channel 5 is a dry period at the beginning of the Holocene; channel 4 is a humid Holocene phase; and channel 3 to the modern channel are the most recent Holocene fluctuations. Sedimentary structures and paleo-hydrologic implications indicate that channels 7 and 6 were laid down by broad, shallow braided streams, Channels 6A and 5 were either braided or coarse meander belt fluvial systems. The small channel width, meander wavelength, and low sinuosity indicates that channels 6B and 4 operated as fine grained meander belt fluvial systems. Channels 3 and 2 are similar to the modern Colorado River which is a bed-load (high bed-load/discharge ratio) stream transporting coarse sand and pebble-to-cobble gravelen_US
dc.description.departmentEarth and Planetary Sciencesen_US
dc.format.mediumelectronicen_US
dc.identifier.urihttps://hdl.handle.net/2152/114774
dc.identifier.urihttp://dx.doi.org/10.26153/tsw/41677
dc.language.isoengen_US
dc.relation.ispartofUT Electronic Theses and Dissertationsen_US
dc.rightsCopyright © is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works.en_US
dc.rights.restrictionOpenen_US
dc.subjectGeomorphologyen_US
dc.subjectTexasen_US
dc.subjectBastrop Countyen_US
dc.subjectFayette Countyen_US
dc.subjectColorado Riveren_US
dc.subjectMapsen_US
dc.subjectLate Quaternaryen_US
dc.subjectUtleyen_US
dc.subjectLa Grangeen_US
dc.subjectSedimentsen_US
dc.subjectChannel morphologyen_US
dc.subjectFlood plain morphologyen_US
dc.subject.lcshGeomorphology--Texas--Bastrop County
dc.subject.lcshGeomorphology--Texas--Fayette County
dc.subject.lcshGeomorphology--Colorado River (Colo.-Mexico)
dc.titleLate Quaternary geomorphic evolution of the Colorado River, Bastrop and Fayette counties, Texasen_US
dc.typeThesisen_US
dc.type.genreThesisen_US
thesis.degree.departmentGeological Sciencesen_US
thesis.degree.disciplineGeological Sciencesen_US
thesis.degree.grantorUniversity of Texas at Austinen_US
thesis.degree.levelMastersen_US
thesis.degree.nameMaster of Artsen_US

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