Glaciers

During the Ice age abou 3 million years ago ice covered the majority of the higher yosemite, and sent glaciers down intothe valley. During the Tioga Glaciation, glaciers covered most areas in and around Yosemite National Park above 8,900 feet (2,700 m) in elevation. Slow moving masses of ice further carved out the valley floor, and created features such as El Capitan. Most of this ice had melted away due to natural warming by about 10,000 years ago. During a more recent cold period called the Little Ice Age, small glaciers formed below the highest peaks. Currently, two remain: the Lyell and Maclure glaciers. These ice bodies are important to local ecosystems because they provide a year-round supply of cold water to the Lyell Fork of the Tuolumne River, especially during the late summer and fall after the winter snowpack has melted. These glaciers are much smaller then the anccient glaciers but still create the same erosional effect but to a much lesser extent.