| A | B |
|---|
| solar energy | energy from the sun |
| precipitation | water that falls to Earth's surface as rain, snow, sleet, or hail |
| surface water | water that is found in Earth's streams, rivers, and lakes |
| groundwater | water found below Earth's surface |
| water vapor | water occurring in the air as an invisible gas |
| weathering | process by which rock is broken down into smaller pieces |
| erosion | the movement of sediment from one location to another |
| earthquakes | sudden, violent movements of Earth's crust |
| lava | magma that reaches Earth's surface |
| theory of continental drift | states that continents were once united in a single supercontinent called Pangaea |
| landforms | shapes on the planet's surface such as hills or mountains |
| mountain | land that rises higher than 2,000 feet |
| valley | area of low land located between mountains or hills |
| island | area of land completely surrounded by water |
| peninsula | land surrounded by water on three sides |
