Reddish twilight clouds at sunset over eroded sedimentary layers, Badlands National Park, South Dakota, USA.

Reddish twilight illuminates clouds in darkening blue sky over layers of ancient sediments on the Loop Road near the Interior Entrance of Badlands National Park, South Dakota, USA. This park has the largest undisturbed mixed grass prairie in the United States. This image was stitched from multiple overlapping photos.