dune
Dune, is a kind of sand in the wind under the accumulation of sand. Its appearance was hill or ridge-like accumulation, the general height of up to a few meters or even tens of meters, individual more than 100 meters. The presence of sand dunes is caused by the wind blowing the unconsolidated material. Dunes are the most widely distributed in desert or semi-desert areas, and can be distributed on the coast, lakes and so on. Dunes are divided into fixed dunes, semi-fixed dunes and mobile dunes according to the degree of flow. They have various shapes such as crescent-shaped, gold-shaped, honeycomb, lattice, parabolic and so on. Bare dunes easy to flow, you can drown arable land, houses, roads, etc., the growth of the dune relatively fixed. Sand dunes due to the long-term choice of wind, uniform size, mud content is very small, suitable for a variety of building materials and industrial raw materials. Most of the dunes are constantly moving because of the wind. Some special dunes, such as Dunhuang Mingsha, but fixed next to the Crescent Moon Spring. ...