what is an ice age : An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and greenhouse periods, during which there are no glaciers on the planet.
how does an ice age effect land and oceans: An ice age causes enormous changes to the Earth's surface. Glaciers reshape the landscape by picking up rocks and soil and eroding hills during their unstoppable push, their sheer weight depressing the Earth's crust.
During most of the last million years, global temperatures were significantly colder than they are today. Ice encroached further toward the equator, sea level was lower, and wind patterns were altered.