Linear dunes are long sand dunes formed parallel to the prevailing wind direction. Some linear dunes are tens of kilometers long.

Formation:
Linear dunes form in very dry areas where there is an abundance of sand. These dunes form where wind comes either from a single direction or from two slightly different directions (bidirectional winds). The dunes generally form within 15 degrees of the prevailing winds. Linear dunes may have two slip faces, one on either side of the crest, with the slip faces changing as wind direction changes.

Two Types

Simple Linear Dunes: Simple linear dunes have single ridges. They have average heights of 10-25 m and average widths of 300-500 m. These dunes may extend for tens of kilometers. Simple linear dunes are common in Australia and the Simpson Desert which are tropical/subtropical deserts.

Compound Linear Dunes: Compound linear dunes can reach heights of 100 m and widths up to 1 km. Smaller dunes form on the larger dune, and the multiple dunes give the name "compound dune". Compound dunes are common in Saudi Arabia, a hyper-arid (super dry) desert.