A caldera is a large depression formed from a collapsed volcano. Calderas are often circular or elliptical.
 Cenozoic era

The "Age of Mammals" (65 million years ago - today), saw the emergence of familiar life forms, humans, the modern look of the continents, and a cooling climate. The Cenozoic followed the Mesozoic Era.

Cinders are small fragments of lava that are about 1/2 inch (1 centimeter) across.


 cinder cone

A cinder cone is a cone-shaped volcano. Its steep sides are formed by volcanic cinders that fall to the Earth close to the vent.

 composite volcano

A composite volcano is a volcano that has a steep volcanic cone that is built up by dense lava flows and pyroclastic debris.

Condensation is the process in which a vapor (gas) is cooled to the liquid phase. Clouds are formed by the condensation of atmospheric water vapor.


A conduit is passage through which
magma (molten rock) flows in a volcano.
A volcanic conduit is a passage through which
magma (molten rock) flows in a volcano.




 continental drift
Continental drift is the movement of the Earth's continents. The land masses are hunks of Earth's crust that float on the molten core. The ideas of continental drift and the existence of a supercontinent (
Pangaea) were presented by Alfred Wegener in 1915.


 continental plates

The crust of the
Earth is broken into plates. The plates are enormous chunks of rock that float atop the soft mantle. The plates are moving at a speed that has been estimated at 1 to 10 cm per year. Continental plates are thicker, older, and less dense than oceanic plates. These plates are about 125 kilometers thick and are made of granite that is about 3 billion years old.
 continental shelf
The continental shelf is the part of the ocean floor next to each of the continents. The sea floor slopes gradually from the continent to a depth of about 650 feet (200 m). Beyond the continental shelf the sea floor drops steeply.


The core is the innermost layer of the
Earth. It consists of iron-nickel; it is under great pressure and is very hot. The inner core is solid ; the outer core is molten.

 Coriolis force
The Coriolis force is the force that results from the rotation of the Earth around its axis; it makes storms rotate counterclockwise in the Northern and clockwise in the Southern Hemispheres. The French engineer/mathematician Gustave-Gaspard Coriolis discovered this force in 1835. This force has effects on water currents, but has no effect on the direction of water going down a drain.

A crater is a circular depression in the ground. It has steep sides and contains a volcanic vent.


  Cretaceous period 
Flowering plants appeared and dinosaurs were at their height during the Cretaceous period, 146-65 million years ago. There was a mass extinction (the K-T mass extinction) at the end of the Cretaceous, marking the end of the dinosaurs and many other species. Modern-day sharks existed during the Cretaceous period.


The Earth's crust is its outermost, rocky layer.


Crystallization is the process in which magma solidifies into solid, crystalline rock.

A current is a non-periodic horizontal movement of water. Currents are caused by winds, temperature differentials, and other forces. They are NOT caused by tidal forces (the gravitational forces of the Moon and Sun). Some major currents include the Gulf Stream in the Atlantic Ocean and the Humboldt Current in the Pacific Ocean.


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