This natural color image, acquired by the Landsat Enhanced Thematic Mapper plus (EMT+) on October 14, 1999, shows the park and its immediate surroundings. To the west of the Sangre de Cristo Mountains is a vast sand field, which extends beyond the left edge of this image. As the wind blow east over the plain, it picks up the sand. Like snow drifting behind a snow fence, the blowing sand is blocked by the mountains and accumulates at their base. Over years, the loose sand has built into massive dunes, which are clearly visible in this image. The dune field forms a light, almost white crescent immediately west of the mountains. The darker sands of the sand field are largely anchored in place by grass and other low plants.
Southwest of the dune fields, on the lower left edge of the image, are the San Luis Lakes. The lakes are just beyond the western border of Great Sand Dunes National Park. The southern border of the park is also visible in this image. It is formed by Highway 6, the straight light line running across the lower edge of the image. The eastern edge of the park extends into the mountains and the northern border is near Sand Creek, the jagged dark brown line across the top of the image.