While Yosemite’s human history dates back almost six millennia, its natural history is much, much older. Some of the granite rock formations that punctuate this scenic landscape date back more than 100 million years, born out of glaciers and eons of slow erosion that have also sculpted its yawning valleys. Many of its tallest mountains exceed 10,000 feet (3,048m), including Mount Lyell, which at 13,114 feet (3,997m) is the highest peak in the national park. This, along with the park's enormous waterfalls and towering trees, helped secure Yosemite World Heritage Site status in 1984.