National Geographic

Encyclopedic Entries


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Weathering describes the breaking down or dissolving of rocks and minerals on the surface of the Earth. Water, ice, acids, salts, plants, animals, and...


Erosion is the geological process in which earthen materials are worn away and transported by natural forces such as wind or water.


Civilization describes a complex way of life characterized by urban areas, shared methods of communication, administrative infrastructure, and divisio...


Climate is the long-term pattern of weather in a particular area.


A yurt is a portable, circular dwelling made of a lattice of flexible wood and covered in felt.

keystone species

A keystone species helps define an entire ecosystem. Without its keystone species, the ecosystem would be dramatically different or cease to exist alt...

GIS (geographic information system)

A geographic information system (GIS) is a computer system for capturing, storing, checking, and displaying data related to positions on Earth’s...


The Arctic is the northernmost region of the Earth


Earth is the planet we live on, the third of eight planets in our solar system and the only known place in the universe to support life.

continental divide

A continental divide is an area of raised terrain that separates a continent’s river systems that feed to different basins....

Earth Day

Earth Day is an annual celebration that honors the achievements of the environmental movement and raises awareness of the need to protect Earth’...


A crater is a bowl-shaped depression produced by the impact of a meteorite, volcanic activity, or an explosion.

flood plain

 A flood plain is a generally flat area of land next to a river or stream. 


A bluff is a type of broad, rounded cliff.

El Niño

El Nino is a climate pattern that describes the unusual warming of surface waters in the eastern Pacific Ocean.


Earth’s core is the very hot, very dense center of our planet.


The mantle is the mostly-solid bulk of Earth's interior. The mantle lies between Earth's dense, super-heated core and its thin outer layer, the crust....

ocean vent

An ocean vent is a fissure in the seafloor that spews hot, often toxic fluids and gases.

ocean trench

Ocean trenches are long, narrow depressions on the seafloor. These chasms are the deepest parts of the ocean—and some of the deepest natural spo...

fold mountain

Fold mountains are created where two of Earth’s tectonic plates are pushed together. 

rift valley

A rift valley is a lowland region that forms where Earth’s tectonic plates move apart, or rift.

seafloor spreading

Seafloor spreading is a geologic process in which tectonic plates—large slabs of Earth's lithosphere—split apart from each other.

continental drift

Continental drift describes one of the earliest ways geologists thought continents moved over time. Today, the theory of continental drift has been re...


The crust is the outermost layer of Earth.


The lithosphere is the solid, outer part of the Earth, including the brittle upper portion of the mantle and the crust.