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.