Environment

3. the regular rise and fall in the level of the sea
5. a group of plants or animals that are the same in some way
6. having a temperature between cool and hot
9. the clear liquid that falls from the sky as rain and that is in seas, lakes, and rivers
10. an animal with four legs and a hard shell that lives mainly in water
11. a situation in which a type of animal no longer exists
14. damage caused to water, air, etc. by dirty or harmful substances

1. a large area of trees growing close together
2. the grey or black gas that is made when something burns
4. the process of cutting down or burning all the trees in a forested area
7. a chemical element that exists in all animals and plants and in coal and oil
8. to change from a solid into a liquid because of heat, or to make something do this
12. a great overflow of water
13. a substance that is burned to give heat or power