Evidence of the Ice Ages
For the last two million years, the climate of our planet has been mostly cold, with great ice caps covering much of Europe, Asia, and North America. Land surface temperatures were 5 to 15 degrees Centigrade cooler than today. The glacial periods were interrupted by warm periods, but the warm periods make up only about 10 percent of the last million years. The mild, stable conditions of the last 10,000 years, during which human civilization has flourished, are not typical of the last two million years.
Topic: Earth Science
Subtopic: Geologic Time
Keywords: Glacial epoch, Paleoclimatology, Global temperature changes
The surface scratches on this sample, from an outcrop of granite gneiss, are called glacial striations.
This sample of windblown dust, or loess, was deposited 23,000 years ago, at the height of the last glaciation, where sediments were washing out of glaciers.