Welcome to post number five in the series we’re calling Mother Earth.
The First Ice Age
Take Earth’s abundant water, add some crazy planetary movement and freezing temperatures and you have yourself an ice age. The first ice age is thought to have been around 2.5 billion years ago. It is known as the Huronian ice age and it occurred during the Proterozoic period. Not everyone agrees on what caused the ice age. They’re not even entirely sure how extensive the ice sheets were. However, there are plenty of theories on the first ice age.
Many people think that the ice age was due to the tilting of the Earth at the time. 2.5 billion years ago, the Earth had a much larger tilt than today. Earth is currently tilted on its axis at about 23.5 degrees. Some scientists think that the planet could have been tilted as much as 54 degrees in the past.
More is known about the later, and most severe, ice age known as the Cryogenian period. From around 800 million to 600 million years ago, the Earth resembled a giant snow or slushball. This nasty period came close to killing most of the life on earth. Levels of carbon 13, present in organic life forms, is present in the fossil record before and after the period but almost entirely gone during. The Cryogenian preserved itself for almost 200 million years.
The sheets of white ice covering the Earth reflected most of the warming UV rays that heated the Earth during this period. Eventually, however, our old friends the volcanoes helped out. By shooting a bunch of CO2 into the air for 200 million years, the volcanoes produced enough greenhouse gases to eventually warm the Earth. If only there were a massive ice age going on right now, humans would be set.
Funnily enough, though, we are actually in an ice age at the moment. An ice age occurs when ice sheets cover significant portions of the northern and southern hemisphere. This would mean we are still living in an ice age now, as the Antarctic and Greenland ice sheets exist. However, the term can also mean the periods of glacial expansion farther than normally occurring. The last one of these glacial periods ended around 10,000 years ago.
The ice ages and glacial movements shaped the planet in more ways than one. They’ve had a massive effect on the landscape, for one. Glaciers are like the abusive parent of the planet, they scar it for life. Much of the US topography, not to mention the world, has been influenced by glaciers during ice ages. Long Island, for instance, is composed of sediment dumped by glaciers. The Great Lakes, as well as Minnesota’s famed 10,000 lakes, were formed by glaciers cutting and moving the Earth’s crust.
Biologically, the ice ages also have an effect. During more recent ice ages, when the planet has been populated by complex life forms, extinctions and redistribution of populations generally occur. And after the Cryogenian ice age, the microbes and bacteria that survived the long chill suddenly began to develop into something more. Shortly after the ice age ended, the warmer oceans and planet began to positively crackle with new life forms. The huge number of new forms of life arising in a short period of time earned this period the nickname the Cambrian Explosion.
Tune in next time, as we discuss how these early life forms, and the complex life forms that arose after the Cambrian Explosion, might have come to be.
Our next article in The Mother Earth Series will explore the life on early earth in greater detail. To keep up with the rest of the series, why not subscribe to our RSS feed. We’ll also give you a free album.