In partnership with The Conversation, #Trending brings you Curious Kids, a series where we ask experts to answer questions from kids.
Where does beach sand come from? – Sly M, age 6, Cambridge, Massachusetts, US
David R Montgomery, professor of earth and space sciences, University of Washington, Seattle, US:
“ Mountains end their lives as the sand on beaches. Over time, mountains erode. The mud, sand, gravel, cobbles and boulders they shed are washed into streams, which come together to form rivers.
As they flow down to the sea, all this sediment is ground up and worn down in nature’s version of a rock tumbler.
Big rocks break down into smaller pieces, so most of what reaches the sea is mud. These silt and clay particles are too small to…