Definitions for "Ice age"
An extended period of time where there is extensive glaciation covering the Earth
also known as the Pleistocene Epoch, this is the geologic period of time when glaciers alternately advanced and retreated over much of North America and Eurasia. The length of the Pleistocene is skill a matter of debate. It may extend from three million to nine thousand years ago. Arizona was never covered by glaciers. However, when glaciers advanced over the land, Arizona's climate became wetter and slightly cooler.
An interval of time in which the climate was colder than it is today, glaciers occasionally advanced to cover large areas of the continents, and mountain glaciers grew; can include many glacials and interglacials.
Keywords:  subduction, zone
Subduction Zone
Keywords:  winter, summers, cool, enough, average
a time when the average temperature of the world cools down enough that cool summers and long winter occur
a long-term period where there is a decrease in the overall global temperature
Keywords:  good, example
a good example