Natural

1. A wetland area where the ground is often saturated with water.
4. A place where water drops down from a high cliff or rock.
6. A dense forest found in tropical areas, with high annual rainfall.
8. A huge mass of ice that moves very slowly down a mountain or through a valley.
12. A mountain that can explode, spewing out lava and ash.
13. A piece of land completely surrounded by water.
14. A low area of land between hills or mountains, often with a river running through it.
15. A vast body of saltwater that covers more than two-thirds of the earth's surface.

2. A wide open area filled with grasses, often home to many types of wildlife.
3. A very dry area where few plants can grow, often covered by sand.
5. A large body of water surrounded by land.
7. A large area covered with trees and other plants.
9. A deep, narrow valley with steep sides, often carved by a river over millions of years.
10. A high, steep rise in the earth, much taller than a hill.
11. A stream of water that flows across the land and empties into a sea or lake.