Why does sand exist at beaches?

Answer: Rocks eroded over millions of years

Rocks eroded over millions of years ✓ — Correct! Sand is mostly tiny fragments of rocks and minerals, created by weathering and erosion over millions of years. Rivers carry these particles to the ocean, where waves and currents sort and deposit them on beaches. Beach sand composition varies - some is quartz from granite, some is volcanic rock, some is coral or shell fragments! White sand beaches have more shell and coral content.

Shells dissolve into sand — Wrong. While some beach sand does contain shell fragments, especially on tropical beaches, most sand comes from eroded rocks. Shells can break down into sand-sized particles but aren't the primary source. Rock erosion over geological time creates most beach sand.

Wind carries desert sand there — Wrong. Desert sand rarely reaches beaches. Beach sand is locally sourced from nearby rock erosion and river deposits. Desert sand grains are actually more rounded from wind erosion, while beach sand is more angular from water action. They form through different processes.