干旱区生态环境知识资源中心

Feathered sand ridges in the northeastern Kumtagh Desert in China cover an area of 4016 km(2) and consist of crescent sand ridges and interridge tongue-shaped dunes. Differences in grain size, mineral composition and albedo between crescent sand ridges and tongue-shaped dunes, and between windward and leeward slopes of tongue-shaped dunes, result in their feathery appearance in aerial and satellite imagery. Measurements of the sand drift potential in the region show that the sand-moving wind for feathered sand ridges can be divided into three sectors; i.e. north-northeasterly, easterly and east-northeasterly sectors roughly corresponding to the southeast, northwest and southwest slip faces. Our findings suggests that the crescent sand ridges resulting from the connection of barchan dunes along the prevailing wind direction are longitudinal dune ridges rather than transverse ones. Tongue-shaped dunes and quasi-dune shapes have obvious distinctions and are new transverse dune types. According to McKee’s dune shape classification, the feathered sand ridges are not a deformation dune type but a complex one. According to Wu’s dune morphological and genetic classification, they are not dune ridges or compound dune ridges that form under the action of unidirectional winds or two winds intersecting at an acute angle, but are complex dune ridges that form under the action of three winds intersecting at an acute angle.