A caldera is a large depression formed from a collapsed volcano.
Calderas are often circular or elliptical.
The Cenozoic followed the Mesozoic Era. 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. A composite volcano is a volcano that has a steep volcanic cone that is built up by dense lava flows and pyroclastic debris. Clouds are formed by the condensation of atmospheric water vapor.