Sierra Escarpment viewed from the east. In the foreground is Tinemaha Reservoir in the Owens Valley. Image: G. Thomas, wikipedia
The Sierra Nevada (Spanish: snowy range) is a mountain range in the Western United States, between the Central Valley of California and the Basin and Range Province. The vast majority of the range lies in the state of California, although the Carson Range spur lies primarily in Nevada. The Sierra Nevada is part of the American Cordillera, a chain of mountain ranges (cordillera) that consists of an almost continuous sequence of mountain ranges that form the western “backbone” of North America, Central America, South America and Antarctica.
The Sierra runs 400 miles (640 km) north-to-south, and is approximately 70 miles (110 km) across east-to-west. Notable Sierra features include Lake Tahoe, the largest alpine lake in North America; Mount Whitney at 14,505 ft (4,421 m), the highest point in the contiguous United States; and Yosemite Valley sculpted by glaciers out of one-hundred-million-year-old granite. The Sierra is home to three national parks, twenty wilderness areas, and two national monuments. These areas include Yosemite, Sequoia, and Kings Canyon National Parks; and Devils Postpile National Monument. The Sierra Nevada range is the highest mountain range in the contiguous United States.
The character of the range is shaped by its geology and ecology. More than one hundred million years ago during the Nevadan orogeny, granite formed deep underground. The range started to uplift four M.A. (million years) ago, and erosion by glaciers exposed the granite and formed the light-colored mountains and cliffs that make up the range. The uplift caused a wide range of elevations and climates in the Sierra Nevada, which are reflected by the presence of five life zones. Uplift continues due to faulting caused by tectonic forces, creating spectacular fault block escarpments along the eastern edge of the southern Sierra.
The Sierra Nevada has a significant history. The California Gold Rush occurred in the western foothills from 1848 through 1855. Due to inaccessibility, the range was not fully explored until 1912.