barchan

plural barchans · alternative barchane · alternative barkan · alternative barkhan

1. alsoattributivegeographyAn arc-shaped shifting sand dune comprising well-sorted (uniformly sized) sand.

   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.

   2010, Robert S[tewart] Anderson, Suzanne P[restrud] Anderson, “Eolian Forms and Deposits”, in Geomorphology: The Mechanics and Chemistry of Landscapes, Cambridge, Cambridgeshire; New York, N.Y.: Cambridge University Press, published 2011, →ISBN, page 482, column 1

   4 more examples

   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.

   1966, E[dwin] S[herbon] Hills, C[liff] D. Ollier, C[harles] R[owland] Twidale, “Geomorphology”, in E. S. Hills, editor, Arid Lands: A Geographical Appraisal (Routledge Revivals), New York, N.Y.: Routledge, published 2024, →ISBN, page 72

   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, and the unverifiable suspicion grows that one has been driven by insensible curves actually southwards.

   1988, Robert Irwin, chapter 8, in The Mysteries of Algiers, London: Viking, →ISBN, page 69

   The structure out here was revealed immediately—desert punctuated by oases in a geography of cruelty, barkhans or traveling sand-dunes a hundred feet high, which might or might not possess consciousness, […]

   2006, Thomas Pynchon, “Against the Day”, in Against the Day, New York, N.Y.: Penguin Press, →ISBN, page 752

   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[…].

   2008, Julie Laity, “Aeolian Processes”, in Deserts and Desert Environments, Chichester, West Sussex: Wiley-Blackwell, →ISBN, page 205, column 2