In geology, a solitary, crescent-shaped dune. It is formed in conditions of limited sand.

A bachran moves towards the horns, over a flat surface typically of pebbles or bedrock. The horn shape of the dune points downwind. There will typically be a gentle slope to the windward side, and a steep slip face on the downwind side. It is a common form in desert areas containing little sand in proportion to harder materials. Sometimes one bachran may overtake and coalesce with another, resulting in a more complex form.

Where sand is more common, dunes take a more "mountainous" form, may be larger, and move more slowly.