mountains are a part of the Rocky Mountains. In the northern and central portions of the forest lie the Absaroka Mountains which were named after the Crow Indian tribe. The majority of the Absaroka Mountains are contained within the forest, with the highest peak being Francs Peak at . The peaks of the Absaroka are basaltic in origin, having been the result of volcanic activity estimated to have occurred 50 million years ago during the Eocene epoch. The rocks are composed of mostly andesite and breccias deposited for millions of years during volcanic events and are atop more ancient sedimentary rocks that are considered to have economically viable mineral wealth. Gold was mined from the slopes of Francs Peak between the years 1890 and 1915, and the small ghost town of Kirwin remains as a legacy of that period. Major tributaries of the Bighorn River, such as the Shoshone and Greybull Rivers, originate in the Absaroka Mountains. Important passes through the Absarokas include Sylvan Pass, which leads to the eastern entrance of Yellowstone National Park; and Togwotee Pass, which provides access to Jackson Hole and Grand Teton National Park. In the far north of Shoshone National Forest a small portion of the Beartooth Mountains are located north of the Clarks Fork of the Yellowstone River. The Beartooths are composed of Precambrian granitic rocks that are amongst the oldest found on Earth. Although often considered a part of the Absaroka Mountains, the Beartooths are distinct in appearance and geologic history. Uplifted approximately 70 million years ago during the Laramide orogeny, the Beartooths consist of vast windswept plateaus and rugged peaks with sheer cliff faces. The Beartooth Highway (U.S. Highway 212) crosses Beartooth Pass, and from there descends to the northeast entrance to Yellowstone National Park. The Wind River Range is in the southern portion of the forest and is composed primarily of Precambrian granitic rock. Gannett Peak, the tallest mountain in Wyoming, is in the northern part of the range. Altogether eight peaks exceed and 119 rise at least above sea level. Fremont Peak, the second highest peak in the range, was originally believed to be the tallest mountain in the Rocky Mountains due to its prominence when viewed from the Oregon Trail by early pioneers. The Wind River Range is popular with mountain climbers because of its solid rock and variety of routes. The Cirque of the Towers in the