Sanakirja.org

Esimerkit

• The sand is usually very well sorted in barchans, for it is constantly re-worked as the dune ‘marches’. The marching also causes cross-bedding inside the barchan, with a dip parallel to the sand-fall face.
• But to follow the dunes around the foot of their slopes is also tedious and one can walk for half a kilometre east or west, finding one barchan linked to another and no easy way through […].
• Barchans and transverse dunes are essentially of the same type, forming and migrating under a unidirectional wind regime. The difference between the two is related to the amount of sand: barchans are isolated mounds, whereas transverse dunes are composed of many barchans coalesced into a single, longer dune form (Tsoar 2001).
• Perhaps the most distinctive is the barchan dune, an isolated crescentic form with arms that stretch downwind. Barchans are not huge, often with heights of only a few meters.