Where does the sand on the beach come from?
For grown-ups: the science
The sand on a beach used to be rock from mountains and cliffs, worn down and carried there by rivers and waves.
Sand mainly comes from rock that breaks down through weathering and erosion. As the particles travel in rain and rivers, they get worn and rounded, and along the coast, waves and currents carry them and sort them by size as they settle. In some places, seashell and coral fragments, or volcanic material, can make up a large part of the sand too.
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Transcript
That soft, sandy beach — where did all that sand come from in the first place?
Rain and wind wear away at mountains and cliffs, cracking the rock into tiny pieces. Those broken bits of rock are the very beginning of sand.
Rainwater carries the rock pieces into a river, tumbling them along the way. Each bump wears away their edges until they turn into round grains of sand.
The river carries the sand all the way to the sea, where waves keep pushing it onto the shore. The lightest, smallest grains pile up there and become a sandy beach.
So beach sand starts as rock that breaks down small, then gets carried along by rivers and waves.