1. canyon canyon: a deep ravine between cliffs often carved from the landscape by a river over a long period of time

2. delta delta: a large, flat area of land at the mouth of a river

3. landform landform: a natural structure on Earth’s surface

4. dune dune: a hill of sand that is deposited by the wind

5. weathering weathering: the various processes that cause exposed rock to break down

6. physical weathering physical weathering: the breakdown of rocks and soils through direct contact with heat, water, or ice

7. erosion erosion: the movement of weathered materials by water, wind, or ice

8. deposition deposition: the process in which materials eroded by water, wind, or ice are dropped in a new place

9. mass movement: the downhill movement of rock and soil because of gravity mass movement

10. sedimentary rock: a rock that formed when sediments were pressed and cemented together sedimentary rock

11. cementing: sediments glued together by minerals dissolved in water cementing

12. fossil: a remnant or trace of an organism from long ago, such as a skeleton or leaf imprint, embedded and preserved on the Earth’s crust fossil

13. fossil fuel: a fuel that formed from the decayed remains of ancient plants and animals fossil fuel

14. alternative energy: any energy from a source that does not use up the Earth’s natural resources or endanger our environment alternative energy

15. solar energy: energy from the sun that is converted into thermal or electrical energy solar energy

16. wind energy: air in motion wind energy

17. hydroelectric energy: electricity that is generated by water power hydroelectric energy

18. geothermal energy: energy from within the Earth geothermal energy

19. biofuels: fuels that can be produced using organic materials made from plants and animals biofuels

20. force: a push or pull force

21. gravity: the force that pulls objects toward each other gravity

22. friction: a force between two surfaces rubbing against each other; friction works against motion friction

23. magnetism: a force that pulls magnetic materials across a distance magnetism