Sand

The most common constituent of sand in inland continental settings and non-tropical coastal settings, is silica (silicon dioxide), often in the form of quartz. However, the composition of sand varies according to local rock sources and conditions. Much of the fine white sand found in coral reef settings, for example, is ground-up coral (limestone) that has passed through the digestion of the parrot fish. Some locations have sands that contain iron, feldspar, or even gypsum.

Sand is transported by wind or water and deposited in the form of beaches, dunes, sand spits, sand bars, and the like. In a desert, sand is a dominant soil type. Sandy soils are ideal for certain crops such as watermelons and peanuts and are often preferred for intensive dairy farming because of their excellent drainage characteristics

also see:

Sand Castle

Sand Dollar

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