where does sand come from?

Where does sand come from?  How are beaches formed? What can you learn about an area by looking at sand?

 Sand is basically the material you get when you get a breakdown in rocks, when the rocks weather and decompose over hundreds of thousands and millions of years. Sand is very interesting and i wonder if sand is going to keep on changing over the course of years. 

You can learn a lot about an area by just looking at the sand. Beaches with white sand are said to be Parrotfishes poop. The reason why the Parrotfishes poop so much is because Parrotfishes do not have stomachs. Their meals pass straight through the long intestine, exploding in a cloud of sand out the backdoor. Larger "Parrotfishes" poop  840 pounds of sand per year. So therefore this is why most of our Hawaiian beaches are made up of white sand. 

After reading these articles on beaches i have learned how to detect where the sand has come from. Every time i go to a beach now i am going to think about this experiment and try to comprehend where that sand has come from and how t has been developed.