Planet Earth: Internal & External Forces

Continent

Landmasses above water on earth.

Solar System

Consists of the sun and the 8-9 known planets, including Pluto.

Revolution

365.25 days in one year, the time taken for Earth to orbit the sun.

Orbit

The path followed by Earth as it revolves around the sun.

Seasons

Result from the changing angle at which the sun's rays strike Earth's surface as it revolves around the sun.

Core

Center of the Earth.

Mantle

Soft layer of molten rock surrounding the Earth's core.

Magma

Molten rock formed in the mantle.

Crust

Thin (19-37 miles thick) outer layer of rock on Earth's surface.

Biosphere

Part of Earth where plants and animals live, including the atmosphere, lithosphere, and hydrosphere.

Atmosphere

Layer of gases surrounding the Earth that protects it from radiation.

Lithosphere

Solid rock portion of Earth's surface.

Hydrosphere

Water portion of the Earth.

Continental Drift

Theory that suggests Earth was once a super-continent (Pangaea) that slowly drifted apart over millions of years.

Oceans

Cover 71% of the Earth's surface.

Hydrologic Cycle

Continuous circulation of water between the atmosphere, oceans, and Earth, involving evaporation, condensation, and precipitation.

Drainage Basin

Area of land where water flows from small streams into a major river on its way to the ocean.

Groundwater

Water held in the pores of rock below the Earth's surface.

Continental Shelf

The earth's surface from the edge of a continent to the deep part of the ocean.

Relief

Difference in elevation of a landform from its lowest to highest points.

Topography

Shows the differences in elevation for landforms in a region, typically on a map.

Tectonic Plates

Enormous moving pieces of the Earth's lithosphere.

Divergent Boundary

Boundary where tectonic plates move apart horizontally.