When you go swimming and you see all the sand, how did it get there? I mean what was there before the sand?

Question: When you go swimming and you see all the sand, how did it get there? I mean what was there before the sand?
- Keywords:
  sand,
  sea
Asked by sassypony to Ed, Hayley, Jason, Nathan, Sophie on 20 Mar 2013.
- Hayley Evers-King answered on 20 Mar 2013:
  
  Usually rock! Sand is made up of lots and lots of tiny bits of rock and other particles that have been eroded over time by the transport of rivers and the action of weather and waves!
- Sophie Holles answered on 20 Mar 2013:
  
  Hayley is right, most sand is made of bits of crushed up rock. Also, white sand around coral is made by parrot fish who eat the coral and poo out white sand! You can hear them scraping the coral with their beaks when you swim with them and see them sprinkling their poo on the sea floor, which is a funny thought when you see the tourists on the beach!

Question: When you go swimming and you see all the sand, how did it get there? I mean what was there before the sand?