Soil forms as the solid rock of the Earth, called bedrock, breaks down. It usually takes thousands of years for soil to form from bedrock. In some places, soil forms directly on top of bedrock. In other places, soil forms on a thick layer of loose rock and mineral material. This material, called sediment, has been carried from distant areas by rivers or glaciers.

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How do different types of soil form?

What materials make up soil?

How important are water and other chemicals in soil?

What is soil erosion and how can we control it?