Landforms
Huge towers of rock formed by the collision of earth's tectonic plates
Mountains
Height above sea level
Elevation
Consisting of salt-water, these comprise about 70% of the earth's surface
Oceans
The path a planet takes around a star
Orbit
The center of the earth--made up of hot iron mixed with other metals
Core
Low-lying stretches of flat or gently rolling land
Plains
A body of land smaller than a continent and completely surrounded by water
Island
A narrow body of water between two pieces of land
Straight
A complete orbit around the sun
Revolution
A layer of rock, about 1,800 miles thick, that surrounds the core
Mantle
Steep-sided low-lands through which rivers have carved a trench
Canyon
A piece of land with water on three sides
Peninsula
Located at the mouth of a river, these are formed when soil builds up over time
Delta
The pole that the earth orbits on
Axis
The uppermost layer of the earth
Crust
A long stretch of land lower than the land on either side
Valley
A narrow piece of land that connects two larger pieces of land
Isthmus
A body of land completely surrounded by water
Island
Time of year with the most hours of sunlight, and the least hours of darkness
Summer Solstice
Huge rock plates that cause earthquakes and volcanoes, and form mountains
Plate tectonics
The process of wearing away material on the earth's surface
Erosion
The study of people--how they live, where they live, how they change, and are influenced by, their environment
Human Geography
The point at which a river originates
Source
Time of year with the fewest hours of sunlight, and the most hours of darkness
Winter Solstice
Huge waves caused by undersea earthquakes
Tsunamis