Basic Types of Dunes - Dune Worlds: How Windblown Sand Shapes Planetary Landscapes - page 75

Fig. 6.8 Elegant water-flume experiments have mapped out the different wind regimes that lead to different barchan forms. This compilation
image courtesy of Keisuke Taneguchi—see also Fig. 17.16 . Similar results have been obtained in numerical experiments

Fig. 6.10 HiRISE image of a 'Tadpole', a hybrid between a dome
and a linear dune. PSP_007663_1350, 50 cm/pixel. This type of dune
appears to be much more common on Mars than Earth. Image NASA/
JPL/U.Arizona

Fig. 6.9 HiRISE image of almost dome-like 'teardrop' barchans. The
presence of two slip faces attests to the multidirectionality of the wind
regime (separated by 60-75), according to the water tunnel
experiments in Fig. 6.8 ). Note the dust devil tracks on these dunes.
Image NASA/JPL/U.Arizona

6.3 Barchanoid Ridge

A series of connected crescentic ridges result in a broadly
linear feature with a single sinuous crest that is formed by
coalescing slip faces (Fig. 6.12 ). The crest may have mul-
tiple slip faces but they are all on the same side of the crest,
indicative of a unimodal wind regime. In general, barcha-
noid ridges form where sand supply is greater than would be

larger megabarchan (see next section) it may be a rather
different process.
Some well-studied barchans are the corridor marching
through the Kharga depression in Egypt, barchans in coastal
Peru and Morocco, and near the Salton Sea in California.