Golden Gate

San Francisco, California

In 1851, the [[rabbit:Mariposa Battalion]], a state militia unit pursuing Ahwahneechee people into the mountains during a conflict over gold country territory, became the first group of European Americans to enter the valley. Lafayette Bunnell, the battalion's physician, later wrote that the sight of the granite walls and waterfalls left him unable to speak. The Ahwahneechee, who had lived in the valley for at least 3,000 years, called it Ahwahnee, meaning "place of the gaping mouth," a reference to the valley's shape as seen from its western entrance. The name Yosemite itself is a corruption of "Yohhe'meti," an Ahwahneechee word meaning "those who kill," which neighboring Miwok bands used to describe the valley's inhabitants. The battalion applied the name of the enemy to the place itself, an irony that persists on every map.

The valley is seven miles long, roughly one mile wide, and enclosed by granite walls that rise 3,000 to 4,000 feet on either side. El Capitan, at the valley's western entrance, presents a sheer vertical face of 3,593 feet, the largest exposed granite monolith in the world. Half Dome, at the eastern end, rises 4,737 feet above the valley floor and appears to have been sliced in half by some vertical blade. Both formations are composed of granodiorite, an intrusive igneous rock that cooled slowly beneath the surface roughly 100 million years ago and was later exposed by the erosion of the softer overlying rock.

The valley's shape is the work of ice, not water. The [[rabbit:Merced River]] carved an initial V-shaped canyon, but it was the glaciers of the Pleistocene that widened it into the flat-floored, steep-walled U-shape visible today. At least four major glacial advances filled the valley with ice up to 3,000 feet thick. The last glacier, which retreated approximately 15,000 years ago, left behind a terminal moraine near El Capitan that dammed the valley and created a lake. Over thousands of years, sediment from tributary streams filled the lake, creating the flat meadow floor that now characterizes the valley. [[rabbit:Bridalveil Fall]], which drops 620 feet from a hanging valley on the south wall, exists because its tributary glacier was smaller than the main Merced glacier and could not carve as deeply. When the ice melted, the tributary valley was left suspended hundreds of feet above the main valley floor.

The Ahwahneechee managed the valley floor with deliberate fire. They burned the meadows regularly to promote the growth of black oak, whose acorns were a dietary staple, and to maintain open sightlines for hunting deer. When European Americans arrived, they found what appeared to be a pristine wilderness but was in fact a carefully maintained landscape. The cessation of indigenous burning allowed conifers to encroach on the meadows, and by the mid-20th century the valley floor was noticeably more forested than it had been in 1851. The [[rabbit:National Park Service prescribed fire program]] has attempted to reintroduce controlled burns, but the proximity of visitor infrastructure makes large-scale burning difficult.

The park's establishment followed an unusual path. In 1864, Abraham Lincoln signed the [[rabbit:Yosemite Grant]], transferring the valley and the Mariposa Grove of giant sequoias to the State of California for "public use, resort, and recreation." This was the first time any government in the world had set aside land specifically for public preservation, predating the creation of Yellowstone National Park by eight years. California managed the grant poorly: livestock grazed the meadows, timber was cut, and James Hutchings, an early hotelier, attempted to claim private ownership of land within the grant. John Muir, who arrived in the valley in 1868 and spent years studying its glacial geology, campaigned vigorously for federal protection. In 1890, Congress created Yosemite National Park around the valley, but the valley itself remained under state control until 1906, when California receded it back to the federal government.

The granite that defines Yosemite is part of the [[rabbit:Sierra Nevada batholith]], a massive body of plutonic rock that stretches 400 miles along the range. The batholith formed as the Farallon Plate subducted beneath the North American Plate, generating magma that rose and cooled in chambers miles below the surface. Differential erosion, controlled by the spacing of joints and fractures in the rock, produced the variety of forms visible in the valley. El Capitan's face is remarkably joint-free, which is why it remains a continuous wall. Half Dome's curved back is an example of exfoliation, where concentric sheets of rock peel away like layers of an onion as pressure from the overlying rock is released. The Royal Arches, on the north wall near the Ahwahnee Hotel, display this exfoliation process in dramatic cross-section.

Yosemite Falls, on the north wall, drops a total of 2,425 feet in three stages, making it the tallest waterfall in North America and the fifth tallest in the world. The upper fall alone drops 1,430 feet, more than twice the height of the Eiffel Tower. Unlike Bridalveil Fall, which flows year-round, Yosemite Falls is fed entirely by snowmelt and typically dries to a trickle by late August. The volume of water varies enormously: in peak spring runoff, the falls discharge roughly 2,400 cubic feet per second, producing a roar audible from the entire valley floor and generating a wind at the base strong enough to flatten hikers.

The valley today receives approximately four million visitors per year, nearly all of them concentrated in seven square miles of valley floor within a park that encompasses 1,169 square miles of backcountry. This concentration creates traffic, noise, and crowding that would have been unrecognizable to Galen Clark, the first guardian of the Yosemite Grant, who spent most of his tenure alone in the valley with a few dozen visitors per year. The Park Service has repeatedly attempted to reduce vehicle traffic, with limited success. A 1980 General Management Plan proposed removing all private vehicles from the valley, a measure that has never been implemented.

The climbing culture that emerged in the valley after World War II fundamentally changed the sport worldwide. [[rabbit:Camp 4]], a walk-in campground on the valley floor, became the informal headquarters of a community of climbers who developed techniques for ascending the big walls. Royal Robbins, Warren Harding, Yvon Chouinard, and Lynn Hill each pushed the boundaries of what was considered possible on vertical rock. Harding's first ascent of El Capitan's Nose route in 1958 took 47 days spread over 18 months. In 2017, Alex Honnold climbed the same route without ropes in 3 hours and 56 minutes. Camp 4 was listed on the National Register of Historic Places in 2003, not for any building, but for its significance as a cultural landscape.

The Ahwahneechee were forcibly removed from the valley in the 1850s and relocated to a reservation on the Fresno River. Some returned and lived in the valley for decades afterward, tolerated by park administrators who employed them as laborers and occasionally displayed them for tourists. The last Ahwahneechee village in the valley was demolished in the 1960s. A reconstructed village near the visitor center interprets their history, though no Ahwahneechee community lives in the valley today.