I recently watched a show on the Discovery Channel about a concept called “Snowball Earth.” Apparently, there has been some evidence that at one time (about 600 million years ago) all of the Earth’s surface was frozen. Just to do a quick (and crude) recap -
They found evidence of glaciation near the equator. The main piece of evidence was the presence of drop stones (is that the right term?), which form when stones are carried on a glacier and the glacier then melts, dropping the stones. Skeptics of the SE theory argued that these rocks were there due to continental drift and originated in the arctic, but when tested (for magnetization), the stones were show to be from the equator. Hence, glaciers in the tropics.
In the 60’s, a scientist studying the potential effects of a nuclear holocaust came up with the “Runaway Freeze” theory. If an imbalance in temperature cause the ice caps to freeze past a certain point, the temperature of the Earth would gradually lower more and more, due to the sun’s rays reflecting off of the snow and ice. This would continue until all of Earth would eventually freeze. If this happened, it would be impossible for the Earth to ever generate enough heat to thaw, thus, no Snowball Earth.
An American scientist in the 90’s theorized that Volcanic activity would still happen during this time, and the Carbon Monoxide would slowly build in the atmosphere (no rain to cleanse the air) until Global Warming was acheived, and the Earth would thaw due to a raised temperature.
Skeptics brought up early life forms which existed in the water at that time in the form of Algae and Stromatalytes. They photosynthesised, and visibility under thick ice is not great, which means that it would’ve been too dark under all that ice for them to survive. We know they continued to thrive way past that time frame, and still exist today.
Then a man from NASA took a trip to Antartica, which has depths of ice about the same as Snowball Earth would’ve. He dived under the ice and found that these organisms were plentiful there. The ice had frozen slowly enough to push out impurities and form like glass, almost completely transparent. Since the Earth supposedly froze slowly, this would also have been the case 600 million years ago. Not only would the life-forms have survived, but the new warmer climate would’ve been a good catalysyt for evolution, a “greenhouse” for new life forms.
So now, the question. Do you believe that this actually happened? I don’t really have an opinion either way, and am trying to keep an open mind about it until I hear more. Anything you want to add, refute, or discuss would be appreciated.
Please forgive any typos, as I have had very little sleep.