martes, 28 de septiembre de 2010


1.Rock: a naturally formed solid in the crust, made up of one or more minerals.

2.Igneous rock: a rock formed when melted rock material cools and hardens.

3.Sedimentary rock: a rock made of bits of matter joined together.

4.Fossil: any remains or imprint of living things of the past.

5.Metamorphic rock: a rock formed under heat and pressure from another kind of rock.

6.Humus: decayed plant or animal material in soil.

7.Pollution: adding any harmful substances to Earth's land, water, or air.

8.Rock cycle: rocks changing from one form into another in a never-ending series of processes.

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