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Sand Movement (sand + movement)
Selected AbstractsExpressing sand supply limitation using a modified Owen saltation equation ,EARTH SURFACE PROCESSES AND LANDFORMS, Issue 12 2008Dale A. Gillette Abstract An analysis of saltation data led us to modify the theory of P. R. Owen using a soil-related parameter ,A' that gave us the possibility of expressing limitation of sand grains of saltation-size in the underlying soil. The value of ,A' was set equal to the ratio of the horizontal flux of saltating particles to Owen's function of wind, times air density divided by gravitational acceleration. Values of A can be used to: (1) characterize the efficiency of the wind to move sand by saltation for different soil textures and aggregations; and (2) to make practical predictions of sand movement based on the condition of the surface soil. Values for A in a range from 1 to 10 are usually associated with supply-unlimited saltation and are usually associated with loose, sandy-textured soils. Values for A in a range from 0·25 to 1 are associated with finer soils that contain more silt and clay. The range of A values between 0 and 0·25 usually reflects finer textured soils that are packed, aggregated, or crusted. A decrease of A to a smaller value is a sign of supply limitation and usually to the soil changing from a looser state to a more aggregated state or more depleted state. Likewise, an increase of A usually corresponds to soil changing from an aggregated state to a looser state. Copyright © 2008 John Wiley & Sons, Ltd. [source] The termination of the last major phase of aeolian sand movement, coastal dunefields, DenmarkEARTH SURFACE PROCESSES AND LANDFORMS, Issue 7 2006Lars B. Clemmensen Abstract Optically stimulated luminescence (OSL) dating of sand samples from stabilized (or inactive) coastal dunes in Denmark provides information on the age of the termination phase of the last major aeolian activity period. A total of 26 sand samples were taken from four different coastal dunefields around the North Sea, Skagerrak and Kattegat coasts of Denmark. The OSL dates indicate that the last major phase of aeolian activity terminated between ad 1860 and 1905. Most of the dunes examined in this study were active around 1820, during a period documented to have been very stormy. A dune management scheme started around 1792, and this no doubt was a major cause of dunefield stabilization, but an overall decline of storminess, particularly spring and summer storminess, around the end of the 19th century must also have contributed to the increasing inactivity of coastal dunes. The new OSL dates on aeolian sand movement agree well with historical data and data from topographic maps on dune movement. This agreement supports the observation from earlier work that OSL dating of recent aeolian sand movement is accurate over the last few decades to centuries. Copyright © 2005 John Wiley & Sons, Ltd. [source] Soilscape and land-use evolution related to drift sand movements since the bronze age in Eastern Jutland, DenmarkGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 2 2007Jari Hinsch Mikkelsen Quarry faces several kilometers long in the Glesborg area in Denmark show that Bronze Age farmers used a sustainable land-use system. Despite nutrient-poor soils, the Glesborg area was under a rotation system in which cropland alternated with grassland. Soil fertility was improved by the addition of household waste and probably also by locally obtained inorganic fertilizer. The soil surface was very stable, and local drift sand movement was limited. Toward the end of the Bronze Age, the landscape changed dramatically with the arrival of overwhelming amounts of drift sand, and farmsteads were abandoned. Subsequent land use on these poor fine sandy soils was no longer capable of maintaining a stable soil surface, and frequent erosion/sedimentation events of more local importance took place. The post-Bronze Age landscape may have been mainly a shifting mosaic of heathland with some temporary arable fields and deflation/accumulation areas. This landscape persisted up to about 200 years ago, when afforestation programs started. © 2007 Wiley Periodicals, Inc. [source] | ||||||||||