Geology of Denali National Park & Preserve

Mount McKinley, Alaska

Mount McKinley, Alaska (Photo credit: jitsen.chang)

Denali National Park & Preserve lies within the Alaska Range, a 600 mile long curved mountain chain. Mount McKinley – or Denali –  is the highest peak in the chain at 20,320 feet, but many peaks reach more than 10,000 feet high. When measured by vertical relief – the elevation from the base to the summit of the mountain – this is the tallest mountain anywhere in the world.

The dome of Mount McKinley is made up mostly of granite. A long, long time ago – 60 million years give or take a couple of million – semi liquid magma invaded the earth’s crust before slowly cooling in the underground chamber forming the dome of Mount McKinley. Some time later, around 38 million years ago, another dome was formed which was to become the neighboring peaks of Mount McKinley. Time moved on and the area where Denali National Park & Preserve stands today was covered by sea depositing tons of sediment. A tropical forest grew next – this explains the coal mines close to the park to this very day at Healy. Eventually, the land began to rise and buckle due to geologic forces and the rock was metamorphosed into what is visible in the park to this very day. The uplifting of the Alaskan Range began around 5 million years ago making it one of the very youngest mountain ranges around. The uplift was, of course, followed by erosion revealing the granite rock surfaces of Mount McKinley and the neighboring peaks. You see granite is so hard that it’s almost erosion resistant, it certainly puts up a good fight anyway.

 

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