Why is there sand under the ocean?

gdec1

If you're standing on the shore watching the sandy beach disappear beneath the waves, you may think that it is probably like a big sandy desert. It's not. The ocean floor is as varied and irregular as the land we can see. It has mountains and plains and valleys and ridges and volcanoes and just about any other land feature you could name. http://www.onr.navy.mil/focus/ocean/regions/oceanfloor1.htm Aug 01 06, 9:43 AM

Gnomon

The ocean's floor is actually for the most amazingly flat, with very few features. It is known as the abyssal plain, because it is so flat. This is because of the method by which it is created, by steady accretion at a constant rate at the mid-oceanic ridges. Most of the ocean floor is covered, not in sand, but a layer of muddy sediment known as "ooze", which is a combination of all the debris that falls down from above. Aug 01 06, 2:08 PM