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  • Olympus Mons, the tallest mountain in our Solar System, towers 21,000 meters above the

  • surface of Mars -- nearly two and a half times the height of Mount Everest. On Earth, you

  • would need a spacesuit to survive at that altitude - but could there even be a mountain

  • that tall here on our home planet?

  • Based on the strength of Earth's gravity and the density and strength of rock, in principle

  • you could make a single conical mountain that stretched between New York and Chicago and

  • soared over 45km! That's twice the size of Olympus Mons and definitely dwarfs Everest.

  • However, there are a couple of reasons why we can't actually have that humongous of a

  • mountain on Earth:

  • For one, Earth's crust is made up of continental plates that essentially float in the semi-solid

  • rock of the mantle below. If you add more weight above the surface, they sink lower

  • into the earth's hot interior, and when they sink far enough, they soften and basically

  • melt. For our conical mountain, that gives a new height limit of just 15km.

  • As well, the powerful collision of two tectonic plates, which creates mountains in the first

  • place, also fractures and cracks the rock, weakening its structure and exposing it to

  • erosion.

  • Over millions of years, freeze-thaw cycles pry at these cracks, while winds claw at the

  • slopes and streams and glaciers carve deep valleys into the mountainside, all weakening

  • the mountain's support. This can end badly.

  • For example, 3,764m tall Aoraki/Mount Cook in New Zealand had its top fall off one night

  • in 1991, trimming it down to a 3,754m mountain.

  • Given all the factors that conspire to limit the height of mountains - sinking into the

  • earth's mantle, fractures, and erosion - I wouldn't bet on our tallest mountains getting

  • too much taller than they already are. Then again, Mount Everest is still growing, 50

  • years from now, it could be 30 cm taller than it is today... or it could be a good deal

  • shorter. We'll just have to wait around to find out. And, who knows? Maybe we'll be on

  • Mars by then, anyway.

Olympus Mons, the tallest mountain in our Solar System, towers 21,000 meters above the

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How Tall Can Mountains Be?

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    cathy~ posted on 2015/05/04
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