The Birch River: a nonconformable fluvial depositional system in a lacustrine transgressive regime

dc.contributor.advisorSmith, Derald G.
dc.contributor.authorMolnar, Theresa M.
dc.descriptionBibliography: p. 97-100.en
dc.description.abstractThe lower Birch River alluvial valley displays morphologic features of a once active laterally accreting meandering river system which includes scroll bar plains and oxbow lakes however, the most recent of these features do not conform to previously documented lateral accretionary deposits and flu vial style. The older scroll bar plains display typical ridge and swale topography, whereas the distal sequences (away from the river) are partially or wholly emersed in water producing small, shallow lakes, which suggests valley aggradation of the alluvial fill. The morphology and stratigraphy of the Birch River alluvial valley and delta is hypothesized to have been and is presently influenced by a lake transgression (Lake Claire) induced by differential postglacial isostatic rebound. This has caused valley and deltaic aggradation and land loss due to rising lake level. Eighty kilometres northeast of the delta, the Riviere des Rochers, the regional hydrologic outlet, is rebounding at a faster rate than the Lake Claire basin, with the net result of pooling and expansion of water in the Lake Claire basin. Lake level rise has resulted in: 1) erosion and drowning of most of the delta front, 2) a decrease of the Birch River gradient producing a change in fluvial morphology and stratigraphy from a laterally to a diagonally to a near-stable meandering river with localized drowned oxbows and point bars, 3) vertical aggradation of the Birch delta and the Birch River alluvial valley. Analysis of subsurface sediments from vibracores combined with six radiocarbon dates on buried wood and peat in the Birch River alluvial valley and delta were used to determine the rates of vertical sedimentation, lateral accretion, and transgression. Calculated rates of lake level rise are 1.0 mm/yr at the northeast margin of the delta and 1.4 mm/yr at the proximal delta. On the basis of radiocarbon dates collected from the proximal delta, Lake Claire may not have existed prior to 3,000 BP and may double in size to about 3000 km2 in 3000 years from now, at which time it will become the largest lake in Alberta, exceeding Lake Athabasca.
dc.format.extentxii, 100 leaves : ill. ; 30 cm.en
dc.identifier.citationMolnar, T. M. (1994). The Birch River: a nonconformable fluvial depositional system in a lacustrine transgressive regime (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from doi:10.11575/PRISM/15871en_US
dc.identifier.lccGB 598.15 M65 1994en
dc.publisher.institutionUniversity of Calgaryen
dc.rightsUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
dc.subject.lccGB 598.15 M65 1994en
dc.subject.lcshDeltas - Alberta - Birch River Valley
dc.subject.lcshAlluvial fans - Alberta - Birch River Valley
dc.subject.lcshBirch River Valley (Alta.)
dc.subject.lcshSedimentation and deposition - Alberta - Birch River Valley
dc.titleThe Birch River: a nonconformable fluvial depositional system in a lacustrine transgressive regime
dc.typemaster thesis of Calgary of Science (MSc)
ucalgary.thesis.accessionTheses Collection 58.002:Box 935 520538888
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