Snowball Earth
Proponents of the Snowball Earth theory claim that around 530 million years ago the Earth was going through an extremely cold period. The oceans were frozen to great depths, and their snow covering reflected the heat from the sun through cloudless skies. Only simple forms of life could survive in locations such as deep oceanic hydrothermal vents. At the end of this period the edges of the West African craton became highly active, throwing up a ring of volcanoes. The thermal activity was caused by excessive mantle heat that had built up below the craton, insulated by the lithosphere. The volcanic eruptions created a greenhouse effect on massive scale, melting the ice and releasing CO2 into the atmosphere. The climate quickly switched to one much warmer than today, resulting in the Cambrian explosion of life forms.
Read more about this topic: West African Craton
Famous quotes containing the words snowball and/or earth:
“When children feel good about themselves, it’s like a snowball rolling downhill. They are continually able to recognize and integrate new proof of their value as they grow and mature.”
—Stephanie Martson (20th century)
“You mean that this little pebble’s been out there hot-roddin’ around the universe?”
—Theodore Simonson. Irvin S. Yeaworth, Jr.. Mooch, The Blob, examining the “meteor” that carried the Blob to earth (1958)