| A | B |
|---|
| geography | the study of the earth in all its variety |
| landform | particular features of the land |
| Global Positioning System (GPS) | a group of satellites around the earth |
| geographic information system (GIS) | special software that helps geographers gather and use information |
| artifact | object made by early people |
| fossil | preserved remains or impressions of early humans, animals or plants |
| solar system | Earth, eight other planets, and thousands of smaller bodies that all revolve around the sun |
| orbit | path that a body in the solar system travels around the sun |
| atmosphere | layer of air surrounding earth |
| axis | imaginary line that runs through the earth's center between the North and South poles |
| revolution | one complete orbit around the sun |
| leap year | year that has an extra day; occurs every fourth year |
| summer solstice | the day with the most hours of sunlight |
| winter solstice | day with the fewest hours of sunlight |
| equinox | day when day and night are of equal length in both hemispheres |
| core | center of the earth, formed of hot iron mixed with other metals |
| mantle | rock layer about 1,800 miles thick between the earth's core and the crust |
| magma | hot, melted rock that sometimes flows to the earth's surface in a volcanic eruption |
| crust | uppermost layer of the earth |
| continent | massive land area |
| earthquake | violent and sudden movement of the earth's crust |
| plate tectonics | theory that the earth's crust consists of huge slabs of rock that move |
| tsunami | huge sea wave caused by an earthquake on the ocean floor |
| fault | a crack in the earth's crust |
| weathering | a process that breaks surface rocks into gravel, sand or soil |
| erosion | wearing away of the earth's surface |
| glacier | giant slow-moving sheets of ice |
| elevation | height above sea level |
| plain | low-lying stretch of flat or gently rolling land |
| plateau | flat land with higher elevation than a plain |
| isthmus | narrow piece of land that connects two larger pieces of land |
| peninsula | piece of land with water on three sides |
| island | body of land smaller than a continent and surrounded by water |
| continental shelf | plateau off each coast of a continent that lies under the ocean and stretches for several miles |
| trench | valley in the ocean floor |
| strait | narrow body of water between two pieces of land |
| channel | body of water wider than a strait between two pieces of land |
| delta | area formed from a soil deposit located at the mouth of a river |
