10.5: Case Study - Yosemite National Park

Yosemite National Park is an American National Park in California, surrounded on the southeast by Sierra National Forest and on the northwest by Stanislaus National Forest. The park is managed by the National Park Service and covers an area of 759,620 acres (1,187 sq mi; 3,074 km2) and sits in four counties – centered in Tuolumne and Mariposa, extending north and east to Mono and south to Madera County. Designated a World Heritage Site in 1984, Yosemite is internationally recognized for its granite cliffs, waterfalls, clear streams, giant sequoia groves, lakes, mountains, meadows, glaciers, and biological diversity. Almost 95 percent of the park is designated wilderness. Yosemite is one of the largest and least fragmented blocks in the Sierra Nevada, and the park supports a diversity of plants and animals.

The geology of the Yosemite area is characterized by granite rocks and remnants of older rock. About 10 million years ago, the Sierra Nevada was uplifted and tilted to form its unique slopes, which increased the steepness of stream and riverbeds, resulting in the formation of deep, narrow canyons. About two million years ago glaciers formed at higher elevations which eventually melted and moved downslope, cutting, and sculpting the U-shaped valley that attracts so many visitors to its scenic vistas.

European American settlers first entered Yosemite Valley itself in 1851. There are earlier instances of other travelers entering the Valley, but James D. Savage is credited with discovering the area that became Yosemite National Park. Despite Savage and other white men claiming their discovery of Yosemite, the region and Valley itself has been inhabited for nearly 4,000 years, although humans may have visited the area as early as 10,000 years ago.

Yosemite was critical to the development of the national park idea. Galen Clark and others lobbied to protect Yosemite Valley from development, ultimately leading to President Abraham Lincoln signing the Yosemite Grant of 1864 which declared Yosemite as federally preserved land. It was not until 1890 when John Muir led a successful movement which had Congress establish Yosemite Valley and its surrounding areas as a National Park. This helped pave the way for the National Park System. Yosemite draws about four million visitors each year, and most visitors spend most of their time in the seven square miles (18 km2) of Yosemite Valley. The park set a visitation record in 2016, surpassing five million visitors for the first time in its history. The park began requiring reservations to access the park during peak periods starting in 2020 as a response to the rise in visitors.

Geology

The first rocks were laid down in Precambrian times, when the area around Yosemite National Park was on the edge of a very young North American continent. The sediment that formed the area first settled in the waters of a shallow sea, and compressive forces from a subduction zone in the mid-Paleozoic fused the seabed rocks and sediments, appending them to the continent. Heat generated from the subduction created island arcs of volcanoes that were also thrust into the ancient area. In time, the igneous and sedimentary rocks of the area were later heavily metamorphosed.

Most of the rock now exposed in the park is granitic, having been formed 210 to 80 million years ago as igneous diapirs 6 miles (10 km) below the surface. Over time, most of the overlying rock uplifted along with the rest of the Sierra Nevada, was removed by erosion. This exposed the granitic rock to much lower pressure, which caused the rock to expand, joint and exfoliate.

Figure 10.6: Geologic Map of Yosemite National Park- California. Image by United States Geological Survey, remixed by Grandiose, licensed under CC BY-SA 3.0

Glaciations

Starting about 2 years ago a series of glaciations further modified the area by accelerating mass wasting through ice-wedging, glacial plucking, scouring/abrasion, and the release of pressure after the retreat of each glaciation. The glaciers tended to strip and transport topsoil and talus piles far down glacial valleys, while less-severe glaciations deposited a great deal of glacial till further up in the valleys.

At least 4 major glacial periods have occurred in the Sierra Nevada; locally called the Sherwin (also called the pre-Tahoe), Tahoe, Tenaya, and Tioga. The Sherwin glaciers were the largest, filling Yosemite and other valleys, while later stages produced much smaller glaciers. The Sherwin may have lasted almost 300 thousand years and ended about 1 million years ago. A Sherwin-age glacier was almost surely responsible for the major excavation and shaping of Yosemite Valley and other canyons in the area.

The Tahoe, Tenaya, and Tioga stages were part of the Wisconsinan glaciation. The Tahoe glacial stage is thought to have reached its maximum extent around 70,000 to 130,000 years ago; little is known about the more recent Tenaya. Evidence also suggests that the most recent local glacial stage, the Tioga, started about 28,000 cal (calibrated Radiocarbon dating) years ago, reached its maximum extent 20,000 to 25,000 cal years ago, and ended by ~15,000 cal yr ago. Glaciers reformed in the highest cirques during a minor late-glacial readvance, the Recess Peak event, between about 14,200 and 13,100 years ago.

Glacial systems reached depths of up to 4000 feet (1200 m) and left their marks in the Yosemite area. The longest glacier in the Yosemite area ran down the Grand Canyon of the Tuolumne River for 60 miles (95 km), passing well beyond Hetch Hetchy Valley. Merced Glacier flowed out of Yosemite Valley and into the Merced River Gorge. Lee Vining Glacier carved Lee Vining Canyon and emptied into Lake Russell (the much-enlarged ice age version of Mono Lake). Only the highest peaks, such as Mount Dana and Mount Conness, were not covered by glaciers. Retreating glaciers often left recessional moraines that impounded lakes such as Lake Yosemite (a shallow lake that periodically covered much of the floor of Yosemite Valley).

Some domes in the park were covered by glaciers and modified into roche moutonnées, which are characterized by having a smooth, rounded side and a steep face. The rounded side was where the glacier flowed over the dome and the steep side is where the glacier flowed away from it. The steepness is caused by glacial plucking of rock along fracture joints. Good examples in the park are Liberty Cap, Lembert Dome, Mount Broderick and Half Dome (figure10.7).

Figure 10.7: Sunset Over Half Dome, Yosemite National Park, California. Photo by DAVID ILIFF is licensed under CC BY-SA 3.0

Half Dome was created by a different process, since erosion acting on jointing planes was still the major factor. Half Dome is a quartz monzonite batholith at the eastern end of Yosemite Valley in Yosemite National Park, California. It is a well-known rock formation in the park, named for its distinct shape. One side is a sheer face while the other three sides are smooth and round, making it appear like a dome cut in half. It stands at nearly 8,800 feet above sea level and is composed of quartz monzonite, an igneous rock that solidified several thousand feet within the Earth. At its core are the remains of a magma chamber that cooled slowly and crystallized beneath the Earth's surface. The solidified magma chamber was then exposed and cut in half by erosion, therefore leading to the geographic name Half Dome.

Cultural History & Influence

Historically attested Native American populations, such as the Sierra Miwok, Mono and Paiute, belong to the Uto-Aztecan and Utian phyla. In the mid-19th century, a band of Native Americans called the Ahwahnechee lived in Yosemite Valley. The California Gold Rush greatly increased the number of non-indigenous people in the region. Tensions between Native Americans and white settlers escalated into the Mariposa War. As part of this conflict, settler James Savage led the Mariposa Battalion into Yosemite Valley in 1851, in pursuit of Ahwaneechees led by Chief Tenaya. The California state military forces burned the tribe's villages, destroyed their food stores, killed the chief's sons, and forced the tribe out of Yosemite. Accounts from the Mariposa Battalion, especially from Dr. Lafayette Bunnell, popularized Yosemite Valley as a scenic wonder.

Native Americans of Yosemite

Humans may have lived in the Yosemite area as long as 10,000 years ago. Habitation of the Yosemite Valley proper can be traced to about 3,000 years ago, when vegetation and game in the region was like that present today; the western slopes of the Sierra Nevada had acorns, deer, and salmon, while the eastern Sierra had pinyon nuts and obsidian. Native American groups traveled between these two regions to trade and raid.

Archaeologists divide the pre-European American contact period of the region into three cultural phases. The Crane Flat phase lasted from 1000 BCE to 500 CE and is marked by hunting with the atlatl and the use of grinding stones. The Tamarack phase lasted from 500 until 1200, marked by a shift to using smaller rock points, indicating development and use of the bow and arrow. The Mariposa phase lasted from 1200 until contact with European Americans.

Trade between tribes became more widespread during the Mariposa phase, and the diet continued to improve. Paiutes, Miwok, and Monos visited the area to trade; one major trading route went over Mono Pass and through Bloody Canyon to Mono Lake in Eastern California, (often acorns from the west with obsidian from the eastern side of the Sierra).

Figure 10.8: Group of Miwok in council by a Cedar Structure in Yosemite Valley Near the Merced River, June 1872. Image by Eadweard Muybridge is in the public domain.

Paiutes were the primary inhabitants of the Yosemite area and the foothills to the east during the Mariposa and historic phases. The Central Sierra Miwoks lived along the drainage area of the Tuolumne and Stanislaus Rivers, while the Paiutes inhabited the upper drainage of the Merced and Chowchilla Rivers.

The Paiutes of Yosemite Valley called themselves the Ah-wah-ne-chee, meaning "dwellers in Ahwahnee.” The Ahwahneechees were decimated by a disease in about 1800, and left the valley, although about 200 returned under the leadership of Tenaya, son of an Ahwahneechee chief.

Displaced Native Americans from the Californian coast moved to the Sierra Nevada during the early-to-mid-19th century, bringing with them their knowledge of Spanish food, technology, and clothing. Joining forces with the other tribes in the area, they raided land grant ranchos on the coast and drove herds of horses to the Sierra, where horse meat became a major new food source.

Then Mariposa Battalion & The First Tourists

The first non-Native Americans to see Yosemite Valley were probably members of the 1833 Joseph Walker Party, which was the first to cross the Sierra Nevada from east to west. The first descriptions of Yosemite, however, came nearly 20 years later. The 1849 California Gold Rush led to conflicts between miners and Native Americans, and the state formed the volunteer Mariposa Battalion as a punitive expedition against the Native Americans living in the Yosemite area. In 1851, the Battalion was led by Major Jim Savage, whose trading post on the Merced River the Awaneechee had raided. This and other missions (the Mariposa Wars) resulted in Chief Teneiya and the Awaneechee spending months on a reservation in the San Joaquin Valley. The band returned the next year to the Valley but took refuge among the Mono Paiutes after further conflicts with miners. Most of the Awaneechee (along with Teneiya) were chased back to the Valley and killed by the Paiutes after violating hospitality by stealing horses.

While the members of that first expedition of the Mariposa Battalion had heard rumors of what could be found up the Merced River, none were prepared for what they saw March 27, 1851, from what is now called Old Inspiration Point (close to the better-visited Tunnel View). Dr. Lafayette Bunnell later wrote:

“The grandeur of the scene was but softened by the haze that hung over the valley – light as gossamer – and by the clouds which partially dimmed the higher cliffs and mountains. This obscurity of vision but increased the awe with which I beheld it, and as I looked, a peculiar, exalted sensation seemed to fill my whole being, and I found my eyes in tears with emotion.”

Camping that night on the Valley floor, the group agreed with the suggestion of Dr. Bunnell to call it "Yo-sem-i-ty", mistakenly believing that was the native name. The term is from the Southern Sierra Miwok word Yohhe'meti, meaning "they are killers," which referred to the inhabitants of the place.

James Hutchings—who organized the first tourist party to the Valley in 1855—and artist Thomas Ayers generated much of the earliest publicity about Yosemite, creating articles and entire magazine issues about the Valley. Ayres' highly detailed angularly exaggerated artwork and his written accounts were distributed nationally, and an art exhibition of his drawings was held in New York City.

Figure 10.9: Drawing of Yosemite Falls by Artist Thomas Ayres, Circa 1855. Image by Thomas Ayres is in the public domain.

Two of Hutchings’ first group of tourists, Milton, and Houston Mann built the first toll route into the valley, with the development of the first hotels in the area and other trails quickly following. Many of the early pioneers in the valley of European descent, and a few Native Americans, are buried in Yosemite Cemetery.

The First Park

The work of Ayres gave Easterners an appreciation for Yosemite Valley and started a movement to preserve it. Influential figures such as Galen Clark, clergyman Thomas Starr King and leading landscape architect Frederick Law Olmsted were among those who urged Senator John Conness of California to try to preserve Yosemite.

President Abraham Lincoln signed a bill on June 30, 1864, granting Yosemite Valley and the Mariposa Grove of giant sequoias to the State of California "for public use, resort and recreation," the two tracts "shall be inalienable for all time". This was the first time in history that a federal government had set aside scenic lands simply to protect them and to allow for their enjoyment by all people.

Simply designating an area, a park isn't sufficient to protect it. California did not set up an administration for the park until 1866 when the state appointed Galen Clark as the park's guardian. An 11-year struggle followed to resolve homesteading claims in the valley. The challenge of increasing tourism, with the need to first build stagecoach roads, then the Yosemite Valley Railroad, along with hotels and other facilities in and around the Valley was met during the rest of the 19th century. But much environmental damage was caused to the valley itself at that time. The problems that Yosemite Park had under state control was one of the factors in establishing Yellowstone National Park as the first completely national park in 1872.

Due to the difficulty of traveling there, early visitors to the valley came for several weeks to a couple of months, often bringing entire families with many possessions. Early hotels were therefore set up for extended stays and catered primarily to wealthy patrons who could spend extended periods away from home. One of these hotels—the Wawona Hotel, built in the 1880s—still operates.

After the Valley became a park, the surrounding territory was still subject to logging, mining, and grazing. John Muir publicized the damage to the subalpine meadows that surround the Valley and in 1890, the government created a national park that included a much larger territory—enclosing Yosemite Valley and Mariposa Grove.

Figure 10.10: President Theodore Roosevelt & John Muir on Glacier Point in Yosemite, 1903. Image by Underwood & Underwood is in the public domain.

In May of 1903, U.S. President Theodore Roosevelt camped with John Muir near Glacier Point for three days. During that trip, Muir convinced Roosevelt to take control of the valley and the grove away from California and give it to the federal government. On June 11, 1906, Roosevelt signed a bill that did precisely that, and the superintendent's headquarters was moved from Wawona to Yosemite Valley.

To secure congressional and State of California approval for the plan, the size of the park was reduced by more than 500 square miles (1,300 km2), which excluded natural wonders such as the Devils Postpile and prime wildlife habitat. The park was again reduced in size in 1906, when logging began in an area around Wawona. Acting superintendent Major H. C. Benson said in 1908 that game is on the decrease. Each reduction of the park has cut another portion of the winter resort of game. The various changes meant that the park was reduced to two-thirds of its original size.

About 12,000 acres between the Tuolumne and the Merced big tree groves were added to the park in 1930 through land purchases by the federal government and matching funds provided by industrialist John D. Rockefeller. Another 8,765 acres near Wawona were added in 1932. The Carl Inn Tract, close to the Rockefeller purchase, was secured in 1937 and 1939.