Here's a view of the Tetons you don't see often. This is taken near Tetonia, Idaho looking east toward Wyoming. Rocks that comprise the Tetons are about 2.7 billion years old. Over a span of 9 million years a block of these ancient rocks were uplifted along a 40-mile fault forming the Grand Tetons. Glaciation in the last 250,000 years has altered the Tetons into their present form.