Storm-controlled oblique dunes of the Oregon coast

Abstract

Research Article| December 01, 1983 Storm-controlled oblique dunes of the Oregon coast RALPH E. HUNTER; RALPH E. HUNTER 1U. S. Geological Survey, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar BRUCE M. RICHMOND; BRUCE M. RICHMOND 1U. S. Geological Survey, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar TAU RHO ALPHA TAU RHO ALPHA 1U. S. Geological Survey, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1983) 94 (12): 1450–1465. https://doi.org/10.1130/0016-7606(1983)94<1450:SODOTO>2.0.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation RALPH E. HUNTER, BRUCE M. RICHMOND, TAU RHO ALPHA; Storm-controlled oblique dunes of the Oregon coast. GSA Bulletin 1983;; 94 (12): 1450–1465. doi: https://doi.org/10.1130/0016-7606(1983)94<1450:SODOTO>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 large (mean height 25 m, spacing 300 m), relatively straight-crested dunes of the central Oregon coast migrate an average of 3.8 m/yr toward an azimuth of 26°. The dunes are transverse to the strong, south-southwesterly winter storm winds that are responsible for their basic form, orientation, and migration. The dry, moderate, north-northwesterly summer winds modify the dune form but not the dune trend.Comparison of the sand transport calculated from wind data and the transport measured from dune migration indicates that the actual transport by the wet southerly winds is only one-third of the amount calculated assuming dry conditions. The resultant (vector-mean) transport rate, as recalculated by comparison of the measured and initially calculated rates, is 34 m3/m·yr toward an azimuth of 45°. The dunes are thus oblique by our definition of an oblique dune (angle between dune trend and resultant transport direction between 15° and 75°).The internal structures of the dunes confirm northward migration during wet conditions. Evidence for deposition during wet conditions includes slipface deposits deformed mostly by sliding and various structures formed by the adhesion of sand grains to wet surfaces. Most summer deposits are not preserved, but those on the basal apron (the gentle north slope at the base of the winter slipface) have a high preservation potential. A depositional model based on dune climbing predicts that the preserved record of oblique dunes formed by an obtuse-bimodal wind regime would consist of tabular sets of crossbeds in which the dip angles increase upward from the base of each set. 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.