2013
The Rocky Mountains’ north-south Teton Range includes 9 peaks in excess of 11,000′ elevation, with Grand Teton being the highest at 13,770′. Beginning just south of Yellowstone National Park, the Teton Range is situated primarily on the Wyoming side of the state border with Idaho, with most of the range’s east slope located in the Grand Teton National Park.
This area, 2.5 billion years ago, was an ancient ocean that gradually filled with sand and volcanic debris. As additional sediment deposited over millions of years, heat and pressure metamorphosed this sediment into gneiss, until eventually magma was forced up through the cracks in the gneiss to form granite, anywhere from inches to hundreds of feet thick.
Then, 6-10 million years ago, stretching and thinning of the Earth’s crust caused movement along the Teton fault: as the fault line’s west block rose to create the Teton Range – the youngest of the Rocky Mountains — the fault’s east block collapsed forming the valley called Jackson Hole.
While the west side of the Teton Range appears as high rolling hills transitioning smoothly into flat pasture, the Teton’s spectacular east-facing granite slope — too young to have eroded into soft hills, and without lower peaks to obscure it — rises dramatically 5,000 to 7,000′ above the valley floor.
