Lightning bugs at twilight dart in this magical composite photo taken in Grand Ledge, Michigan. Get the story behind the picture and download the wallpaper »
Photo composite by Vincent Brady, National Geographic Your Shot
'Scapes @ White Sands'
Various forms of dunes are found within the limits of White Sands in New Maxico. Dome dunes are found along the southwest margins of the field, transverse and barchan in the core of the field, and parabolic dunes occur in high numbers along the northern, southern, and northeastern margins. These dunes contain solely of Gypsum which is rarely found in the form of sand because it is water-soluble. Normally, rain would dissolve the gypsum and carry it to the sea. The Tularosa Basin is enclosed, meaning that it has no outlet to the sea and that rain that dissolves gypsum from the surrounding Mountains is trapped within the basin. The dunes constantly change shape and slowly move downwind.