Accession Number : ADA133099

Title :   Surface and Subsurface Geologic Conditions Along Selected Reaches of the Mississippi River from Rosedale, Mississippi to Lake Providence, Louisiana.

Descriptive Note : Final rept. Feb 79-Jan 80,


Personal Author(s) : Murphy,William L

PDF Url : ADA133099

Report Date : Sep 1983

Pagination or Media Count : 124

Abstract : Continuous acoustic subbottom profiling was conducted in 100 miles of the Mississippi River channel near Lake Providence, La., and from below Greenville, Miss., upstream to Rosedale, Miss. Subbottom profiling and other geologic, hydrographic, and topographic data were analyzed to determine the depth, composition, and extent of important geologic horizons beneath the channel and surficial deposits adjacent to the channel in the floodplain. The Tertiary surface as well as bedding and structure within the Tertiary were interpreted from the subbottom profiles for most of the survey area. The geology and stream geometry (thalweg slope and sinuosity) were compared for the river segments studied to determine their relationship to stream degradation and aggradation. Geologic profiles and maps were constructed at an original scale of 1:20,000 from all available data from the surveyed areas and are presented in the report. Computed thalweg slopes for the survey segments were generally flat or increased in elevation in a downstream direction, implying a tendency for the channel to shoal, especially in the Lake Providence and Greenville reaches. Regional geological structure, the lithology of Tertiary deposits underlying the Mississippi River, and alluvial deposits of variable erosion resistance in the flood-plain apparently hamper the river's ability to deepen its channel and to maintain sufficient flow velocity to prevent aggradation in the study reaches. (Author)

Descriptors :   *Channels(Waterways), *Structural geology, Bottom, Surfaces, Profiles, Seismic waves, Acoustic reflection, Soils, Rock, Mississippi River, Louisiana

Subject Categories : Geology, Geochemistry and Mineralogy
      Hydrology, Limnology and Potamology

Distribution Statement : APPROVED FOR PUBLIC RELEASE