One of the best things about YouTube is its animated timelines for human or geological history. This one shows the movement of continents from the beginnings of large, organized life almost 550 million years ago. (Simpler life apparently started billions of years earlier, but left much more ambiguous traces.)
One of my favorite parts is the subcontinent of India shooting off towards Asia like something shot out of a sling. That's some impact. It started about 50 million years ago, which was before people, but after dinosaurs. India was hanging around down near Madagascar when it got caught on a fast conveyor belt that was getting sucked under Asia. It looks like a floating raft headed for a storm drain, but too big to fit. Australia is still on a collision path with Asia, though a much slower one.
This video was embedded in an interesting article from Watts up with That, summarizing the hot and ice ages over the last 550 million years, the point being that Earth's heating and cooling during geological eras is affected by the predominance or scarcity of continents in the tropical zones. We are currently in a 30-million-year-old ice age, a condition encountered only about a tenth of the time over geological timescales, but because we evolved during it, it strikes us as the way things ought to be for "life." In fact, however, we're in a geological brief interglacial period within a much more severe ice age. Humans wouldn't care for the more severe manifestations of a typical ice age.
Why are there ice ages? There is an interesting, but far from settled, link between the Sun's orbit through the Milky Way Galaxy and the typical 150-million-yearish cycle of ice ages.
That explains the Himalayas, I suppose.
ReplyDeleteI always knew the Himalayas resulted from the collision, I just didn't realize what a dramatic movement was involved.
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