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The coldest period of a glacial age. In the ice age 20,000 years ago, ice sheets reached down as far as 40° north (the position of New York).
An era during which a continent is covered by ice sheets (huge aggregations of glaciers). Presently Greenland and Antarctica are covered in such sheets, and are therefore in a glacial age. Current glacial ages alternate cyclically between cold ice ages and warm interglacial ages.
2.5 billion to 500 million years ago, an era in which photosynthetic cyanobacteria produced atmospheric oxygen. The era preceding the Cambrian, when there was a period of accelerated evolution.
Sediment and other deposits from glaciers including rocks and rubble picked up during glacial movement.
Banded iron deposits, manganese deposits, and cap carbonates. Ice-covered seas mean that metallic ions accumulate in the seas and CO2 from volcanoes in the atmosphere. Once the ice melts the metallic ions react with atmospheric oxygen to form deposits, and the massive quantities of CO2 cause cap carbonates through weathering.
Global warming accelerates weathering of the Earth's surface, a chemical reaction in which carbon dissolves minerals. This results in an increase in CO2 consumption, causing temperatures to drop. On the contrary, declining temperatures cause weathering to slow, decreasing CO2 consumption and increasing temperatures. Thus, the tendency is for the climate to stay balanced.
A theory that the Earth's crust is formed of 10 or more plates that are one hundred kilometers thick and move on top of the Earth's mantle convection.
