As recently as 2000 years ago nearly all of Yosemite National Park, including the promontory of Cloud’s Rest where we sat, had been covered by a 60-mile-long, 2000 foot thick glacier that extended from Mt. Lyell, Yosemite Park’s tallest peak to our southeast, all the way down the Grand Canyon of the Tuolumne River to our northwest. Only the tips of the highest peaks in the area protruded from the top of the ice.