Period during which polar ice extends to much lower latitudes than normal.
A glacial epoch or time of extensive glacial activity
A major interval of geologic time during which extensive ice sheets ( continental glaciers) formed over many parts of the world.
The best known ice ages are 1) the Huronian in Canada, occurring very early in the Proterozoic era (2700–1800 million years ago); 2) the pre-Cambrian and early Cambrian, which occurred in the early Paleozoic era (about 540 million years ago) and left traces widely scattered over the world; and 3) the Permo-Carboniferous, occurring during the late Paleozoic era (from 290 million years ago), which was extensively developed on Gondwana, a large continent comprising what is now India, South America, Australia, Antarctica, Africa, and portions of Asia and North America. The term ice age is also applied to advances and retreats of glaciers during the Quaternary era.
Periods in the history of the earth characterized by a growth of the ice caps towards the equator and a general lowering of global surface temperatures, especially in temperate mid-latitudes. The most recent ice age ended about 10,000 years ago. Ice advances in this period are known to have altered the whole pattern of global atmospheric circulation.