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Multiple websites state that the mountain, which is in Colorado, was formed by an intrusion of magma about 1.4 billion years ago, forming a batholith.

On the other hand, the rocky mountains are said to have been formed only recently, perhaps 80 to 50 million years ago.

What then were the major forces that shaped the mountain? Did the batholith 1.4 billion years ago start thrusting the ground upward like a dome mountain, or did it remain flush underground until tectonic plate movement formed all of the rocky mountains?

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    $\begingroup$ Could you site the websites you are referring to, please? $\endgroup$ – arkaia Oct 20 '20 at 22:00
  • $\begingroup$ The granite is old. The mountain is fairly young. There is no contradiction. $\endgroup$ – David Hammen Oct 23 '20 at 15:04
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Just to elaborate on David Hammen's correct comment:

The granite is old. The mountain is fairly young. There is no contradiction

Mountain belts like the Rockies are built by tectonic forces. Two plate collide, and mountains rise in between. The material that makes up the mountain does not have to form during the collision (although it sometime does).

A "batholith" is just a collection of many granite intrusions, which are mostly underground. They do not have to be mountainous. In most cases they are covered by sedimentary rocks and you don't even know they're there. They only become mountains when you "fold" them. When you fold a piece of paper and it wrinkles, you have to separate the formation of the wrinkles (which happened now) from the manufacturing of the paper (which was in a paper factory, in the past).

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  • $\begingroup$ I'm guessing that the upper parts of the folds were isostatically uplifted and then the sedimentary rocks eroded away, exposing the granite? $\endgroup$ – Keith McClary Oct 28 '20 at 2:21

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