Though they are made of ancient rock, the Teto…

Though they are made of ancient rock, the Tetons are one of the youngest mountain ranges in North America. They have been uplifting for less than 10 million years, making them “adolescent” mountains, as compared to the “middle-aged” Rockies (60-80 million years old) or the “elderly” Appalachians (more than 300 million years old). Erosion has had much less time to work in the Teton range, comparatively, so their peaks remain rough and rugged – a major factor in the iconic appeal of Grand Teton National Park in Wyoming. Photo @GrandTetonNPS by John Tobiason, National Park Service.