In a previous post, we mused about the age of celestial objects and the light from distant stars. But now, let’s consider the planet beneath our feet.
What’s the oldest thing you can see on Earth?
The oldest living tree found to date is nearly 10,000 years old. While that’s very impressive, non-living objects can surely last longer. Mount Everest, for example, is about 60 million years old. Dividing 60 million years by 4.5 billion years (the approximate age of the earth) we get a quotient of 0.01333…, meaning Mount Everest is only about 1.33% as old as planet Earth. Want a refresher on calculating percents? Check out this Virtual Nerd tutorial.
From wikipedia.org
How about the Grand Canyon? The Grand Canyon in Arizona began to be eroded out of the rock about 6 million years ago. That’s peanuts compared to Mount Everest, right? It sure is, until you start looking within the Grand Canyon. The Colorado River, in carving the canyon, has exposed layers of rock that rival in age anything you can see, looking up, around, or down (in visible light). Some of the rocks viewable date back to about 1.75 billion years ago. Dividing that number by the age of the earth, we get a result of 0.3888…, or about 39%. Those rocks have been around for more than a third of the time this whole planet has been around!
If only rocks could talk!
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