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How Tall Can Mountains Be?
How Tall Can Mountains Be?
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0:00
Olympus Mons, the tallest mountain in our Solar System, towers 21,000 meters above the
0:04
surface of Mars -- nearly two and a half times the height of Mount Everest.
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On Earth, you would need a spacesuit to survive at that altitude - but could there even be
0:11
a mountain that tall here on our home planet?
0:14
Based on the strength of Earth's gravity and the density and strength of rock, in principle
0:18
you could make a single conical mountain that stretched between New York and Chicago and
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soared over 45km!
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That's twice the size of Olympus Mons and definitely dwarfs Everest.
0:27
However, there are a couple of reasons why we can't actually have that humongous of a
0:30
mountain on Earth:
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For one, Earth's crust is made up of continental plates that essentially float in the semi-solid
0:37
rock of the mantle below.
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If you add more weight above the surface, they sink lower into the earth's hot interior,
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and when they sink far enough, they soften and basically melt.
0:45
For our conical mountain, that gives a new height limit of just 15km.
0:49
As well, the powerful collision of two tectonic plates, which creates mountains in the first
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place, also fractures and cracks the rock, weakening its structure and exposing it to
0:58
erosion.
0:59
Over millions of years, freeze-thaw cycles pry at these cracks, while winds claw at the
1:03
slopes and streams and glaciers carve deep valleys into the mountainside, all weakening
1:07
the mountain's support.
1:08
This can end badly.
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For example, 3,764m tall Aoraki/Mount Cook in New Zealand had its top fall off one night
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in 1991, trimming it down to a 3,754m mountain.
1:20
Given all the factors that conspire to limit the height of mountains - sinking into the
1:24
earth's mantle, fractures, and erosion - I wouldn't bet on our tallest mountains getting
1:28
too much taller than they already are.
1:29
Then again, Mount Everest is still growing, 50 years from now, it could be 30 cm taller
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than it is today... or it could be a good deal shorter.
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We'll just have to wait around to find out.
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And, who knows?
1:40
Maybe we'll be on Mars by then, anyway.
