Quaternary Coasts of the United States: Marine and Lacustrine Systems
Quaternary Coasts of the United States: Marine and Lacustrine Systems Project #274 Quaternary Coastal Evolution - This Special Publication represents the major cumulative contribution of the Working Group of the United States of America to IGCP Project 274. The primary aims of Project 274 are to: (1) document and explain local to global variations in coastal and continental-shelf evolution, incorporating knowledge of coastal and shelf processes and environment with geodynamic, climatic, oceanographic and other data to produce local and regional models, ranging from descriptive to numerical, leading to a better understanding of interactive forces responsible for past, present and future changes to the coasts of the world; and (2) promote specified thematic studies, which are necessary to solve problems of coastal change affecting human occupation of the coastal zone. The volume contains sections on Atlantic, Pacific, Gulf and Lacustrine shorelines, covering both Holocene and Pleistocene deposits, representing a summary of decades of research into coastal and continental-shelf evolution of North America.
Late Quaternary Deposits Near Point Sal, South-Central California: A Time Frame for Coastal-Dune Emplacement
Published:January 01, 1992
Antony R. Orme, 1992. "Late Quaternary Deposits Near Point Sal, South-Central California: A Time Frame for Coastal-Dune Emplacement", Quaternary Coasts of the United States: Marine and Lacustrine Systems, Charles H. Fletcher, III, John F. Wehmiller
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Extensive coastal dunes rise southward from the Santa Maria Valley to the Point Sal Ridge, south-central California. In Mussel Rock ravine and elsewhere, eolian sands occur in association with fluvial deposits. Radiocarbon ages and correlative deposits in nearby areas indicate a sequence of events postdating marine-terrace deposits of oxygen isotope stage 5. Dissected paleodunes (Qe,), probably related to stage 4, are overlain by mostly sandy fluvial deposits (Qf) whose higher units yield 14C ages in the 30- to 23-ka range. Transverse paleodunes (Qe2) began to form after 26 ka, as sea level fell during the transition from stage 3 to stage 2, and probably continued to accumulate westward during stage 2. Parabolic dunes (Qe3) formed from new and reactivated sand masses during the Flandrian transgression and were stabilized before 3 ka. Lobate dunes (Qe4) subsequently formed and the presently active transverse dunes (Qe5) have developed within the past 200 years. The chronology revealed near Point Sal may provide a valuable time frame for coastal-dune development elsewhere in California. The investigation indicates, for example, that extensive transverse dunes form during periods of sediment abundance, ideally when sea level falls and large quantities of sand are exposed on emergent continental shelves, but also when stabilized dunes are reactivated by environmental changes, including human land use. Parabolic dunes develop during periods of sediment deficiency—for example, as sea level stabilizes following a marine transgression.