Vocabulary#14

rock a natuarally formed solid in crust, made of one or more minerals.

igneous rock  a rock formed when melted rock  material cools.

sedimentary rock  a rock made of bits of matter joined together.

fossil any remains or imprint of living things of the past.

metamorphic rock  a rock formed under heat and pressure from another kind of rock.

humus  decayed animal or plant material soil.

pollution  adding any harmful substances to Earth's land, water, or air.

rock cycle rocks changing from one form into another in a never-ending processes.