How did rocks in the Cascade Mountains become sand on a beach in the California cost?

Answer 1

Sand is simply crushed rocks deposited by water, or from some other source. If rocks from the Cascade Mountains somehow got to the California cost and got ground up, it would become sand.

Answer 2

Rocks in the Cascade Mountains eroded over time from weathering processes like wind and water. The eroded rock material was then carried downstream by rivers and streams, eventually reaching the Pacific Ocean where it was further broken down into sand particles. These sand particles were then transported along the coastline by waves and currents to form beaches in California.