The study of dune morphology represents a valuable tool in the investigation of planetary wind systems--the primary factor controlling the dune shape is the wind directionality. However, our understanding of dune formation is still limited to the simplest situation of unidirectional winds: There is no model that solves the equations of sand transport under the most common situation of seasonall...

In the present work, we use dune modeling in order to investigate the evolution of transverse dunes in the presence of vegetation. The vegetation is allowed to grow up to a maximum height Hmax with a growth rate R that oscillates in time. We find that the presence of the vegetation establishes a maximum height for the transverse dunes. If the transverse dune is larger than this maximum size, th...

Vegetation greatly affects the formation and dynamics of dune fields in coastal areas. In the present work, we use dune modelling in order to investigate the genesis and early development stages of costal dune fields in the presence of vegetation. The model, which consists of a set of coupled equations for the turbulent wind field over the landscape, the saltation flux and the growth of vegetat...

In this work, we present measurements of the height profile, wind velocity and sand flux performed on transverse dunes in the dune field known as “Lençóis Maranhenses”, northeastern Brazil. From the measured profile, we selected one dune to measure the air shear stress and the sand flux and compared the results with the theoretical predictions from a dune model in two dimensions recently introd...

Running performance depends on a mechanical interaction between the feet of an animal and the substrate. This interaction may differ between two species of sand lizard from the Mojave Desert that have different locomotor morphologies and habitat distributions. Uma scorparia possesses toe fringes and inhabits dunes, whereas the closely related Callisaurus draconoides lacks fringes and is found o...

Optical and radiocarbon dating indicates that alluvium underlying dunes near Abilene was deposited at or before 45 ka, and that the overlying dunes were active at 1.1–0.5 ka. Geochemical data indicate that the Abilene dune sand is immature and was derived from the underlying Pleistocene alluvium, and not from Holocene age Smoky Hill River deposits. These findings suggest that dune activation wa...

Horqin Sandy Land is located in northeast China (4241’-4515’N, 11835’-12330’E). The wind-sand topography in Horqin Sandy Land can be described as two series--sand deposition and wind erosion. Wind is the natural force for the formation of wind-sandy environment, under windsandy environment, the wind erosion processes such as sand drifting, dust-storm, etc. occurred frequently because of the fre...

Sand dunes have been observed throughout the surface of the planet Mars. Movement of these dunes has been theorized and inferred from the lack of craters on dunes. Dune movement has not yet been directly imaged, however. Understanding sand movement processes is vital to a correct Martian climate model, as well as the safety of future missions to Mars. Imagery from several Martian orbiters was a...

this study aims to identify favorable oil–gas reservoir facies in the chishan group of the wubao fault zone (gaoyou sag, subei basin, china) using the methods of outcrops and cores observation, granularity analysis, scanning electron microscope, log data, etc. the results suggest that the chishan group in the studied area mainly develops desert sedimentary system, and contains five kinds of fac...