Question

what are sand dunes?​

Answer 1

Hey bro.,. here is ur answer

A sand dune is a mount, hill or ridge of sand that lies behind the part of the beach affected by tides. They are formed over many years when windblown sand is trapped by beach grass or other stationary objects. ... Without vegetation, wind and waves regularly change the form and location of dunes.

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Answer 2

When the wind blows, it lifts and transports sand from one place to another. When it stops blowing the  sand falls and gets deposited in low hill. These are called sand dunes.