An Overview of the Five Major Ice Ages
is currently experiencing a warm interglacial that started around 11,000 years ago. The last glacial had peaked 20,000 year ago. The average global temperature back then was about 10°F (5°C) colder than it is now, and some regions were 40°F (22°C) colder than they are now.
Ice ages are not normal, for the Earth has been ice-free for 85 percent of its history. The first known ice age was the Huronian ice age or Icehouse Earth. It lasted from 2400 to 2100 million years ago. It took place after the Great Oxygenation Event which saw a lot of oxygen enter the Earth's atmosphere. The oxygen reacted with methane and greatly reduced its concentration. That triggered a decline in global temperatures and brought about an ice age.
The Huronian ice age was named after Lake Huron, the site of some ancient glacial deposits. It was the longest known ice age and was probably one of the most severe. The only organisms on Earth at the time were very simple one-celled creatures.
Also known as the Cryogenian Ice Age, it lasted from 850 to 635 million years ago. It was actually several severe ice ages that happened one after the other. It owes its nickname to the hypothesis that the glaciation was so extreme and severe that it reached the equator and therefore covered the whole planet. Some scientists speculate that the microorganisms alive at the time survived by taking refuge in the deep and unfrozen parts of the ocean.
Andean-Saharan Ice Age
The Andean-Saharan Ice Age lasted from 460 to 430 million years ago. Evidence indicating its occurrence have been found in the Andes, the Brazilian Amazon region, western Africa, the Arabian Peninsula, and the Sahara desert
Karoo Ice Age
The Karoo ice age owes its name to the Karoo region of South Africa were glacial tills from this ice age were found. It lasted from 360 to 260 million years ago, and oxygen, again, is believed to have been the cause. Land plants had evolved by the beginning of the Devonian and they raised oxygen and decreased carbon dioxide levels in the atmosphere. That led to a cooling of the climate.
Quaternary Ice Age
This current ice age began about three million years ago. While the Earth is in a warm interglacial, there are still ice sheets on Antarctica and Greenland, and the existence of the ice sheets means the current time is an ice age.
About the Author
Lubomir Cizek studied Mining Engineering and Geology at the Mining Academy in Ostrava, Czech Republic. He has also spent a lot of time at a telescope and a lot of time studying astronomy. For more information, please visit http://iceagetheory.com/
Submitted on: 2015-07-21 20:22:15