Why do sand beaches exist?
Show answer & explanation
Answer: Waves grind rock into particles
Fish create sand particles — Wrong. Parrotfish do produce some sand from eating coral, but the vast majority comes from wave erosion of rocks and shells.
Underwater volcanoes erupt sand — Wrong. Volcanoes produce lava/ash, not sand directly. Beach sand forms primarily from wave erosion breaking down rocks over time.
Waves grind rock into particles ✓ — Correct! Waves constantly crash against rocks, breaking them into smaller pieces. Rivers carry eroded rock to coasts. Continuous wave action grinds rocks, shells, and coral into sand-sized particles. Quartz is common in sand because it resists weathering. Black sand beaches form from volcanic rock. White sand from coral/shells!