Question

what are sand dunes​

Answer 1

In physical geography, a dune is a hill of loose sand built by aeolian processes (wind) or the flow of water. Dunes occur in different shapes and sizes, formed by interaction with the flow of air or water. Dunes occur in some deserts and along some coasts

Answer 2

When the wind blows wind lift and carry send from one place to another. when it stops blowing this and fall syndicates deposited in low Hill like structures. these are called sand dunes.