Where Sand Dunes Form: Coasts, Deserts, Riverbeds, and Inland Basins

Sand dunes arise wherever loose sand and wind coincide:

• Coastal areas: Onshore winds build dunes that protect shorelines from erosion.
• Deserts: Vast dune fields (ergs) in the Sahara, Namib, Arabian, and Gobi deserts.
• Riverbeds: In arid regions, ephemeral rivers deposit sand later reworked by wind.
• Inland basins: Ancient lakebeds or glacial outwash plains (e.g., Great Sand Dunes, Colorado).

Dune shape (barchan, transverse, star, parabolic) depends on wind regime, sand supply, and vegetation.