GRAND TETON NATIONAL PARK — The Yellowstone Volcano Observatory (YVO) fixed its gaze on the Tetons this week, reviewing how the Tetons were formed ni this week’s Caldera Chronicles.
Still actively evolving today, the Tetons are dramatic, serving as the focal point for photos from engagement portraits to roadtrip snapshots.
“The tectonic forces that built the range are still active, and stress continues to build even if the Teton Fault has not experienced major movement in recorded history,” geologist with the U.S. Geological Survey Stanley Mordensky writes.
Not only that, but the way the Tetons formed “differ fundamentally” from the other mountain ranges in the Greater Yellowstone Ecosystem (GYE).
Approximately 2.7 billion years ago, the area where the Tetons are today was underwater, according to Mordensky. The sediment that accumulated on the seafloor eventually was pushed by tectonic plates five to ten miles beneath the surface, and the atmospheric pressure metamorphosed the sediment into gneiss. Gneiss is a rock with banding of light and dark minerals and can be found along the Inspiration Point Trail in Grand Teton National Park (GTNP).
While tectonic plates were shifting across North America around 10 million years ago, the Tetons as they are known today began to form. The Teton Fault, which is a 44-mile long fracture running north to south creates the skyline seen from the valley. Whenever the fault moves, the valley drops downward while the mountains grow up. Glaciers also carved out many of the U-shaped valleys of the Tetons.
Evidence of the continued growth can be seen in real-time. Every now and then, residents feel earthquakes, and last summer the Second Tower on the Grand Teton collapsed.
According to Mordenskey, the Tetons are under stress. Eventually the stress will realease, and the Tetons will move again.
