About 2.6 million years ago, a unit of time named the quaternary period (the current and most recent of the three periods of the Cenozoic era) began. This period has been characterised by a long-term reduction in the temperature of the Earth’s surface or time of glaciation or ice age. During that period, the Earth got covered with large thick ice sheets. The probable reasons behind it could be changes in ocean currents, atmosphere or in position of the Earth around the Sun.
Ice Age
