Tutorial:Wind Deposition
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[edit] Wind Deposition
Wind-blown (aeolian) deposits include loess blankets and dune forms.
Around 10% of the earths land surface is covered by loess. Loess consists of well sorted, fine-grained deposits - predominantly silt; loess is often derived from exposed glacial outwash deposits. Loess tends to blanket the land surface smoothing out surface topography, though occasionally dune like forms may form.
Dunes and ripples are more commonly associated with sand sized particles. Ripples, similar to those formed in water are asymmetric with the steepest gradients on the lee-side. Dunes are much larger features, with heights up to 400m and wavelengths up to 4 km. Again, the leeward side is typically the steepest. Unless the surface of the dune is stabilised by vegetation the sand in the dune will keep moving (generally by saltation) and the dune can migrate burying pre-existing land surfaces and settlements in its path.
Examples of burial by wind deposition, often include coastal settlements such as Skara Brae in Orkney. Here rapid burial by shell sand has resulted in remarkable preservation of Neolithic stone houses.
