Yosemite National Park | Yosemite Weather | Yosemite Lodging

About Yosemite National Park:

Yosemite National Park is a United States National Park spanning eastern portions of Tuolumne, Mariposa and Madera counties in east central California, United States. The park covers an area of 761,268 acres (3,080.74 km2) and reaches across the western slopes of the Sierra Nevada mountain chain. Over 3.7 million people visit Yosemite each year: most spend their time in the seven square miles (18 km2) of Yosemite Valley. Designated a World Heritage Site in 1984, Yosemite is internationally recognized for its spectacular granite cliffs, waterfalls, clear streams, Giant Sequoia groves, and biological diversity. Almost 95% of the park is designated wilderness. Although not the first designated national park, Yosemite was central to the development of the national park idea, largely owing to the work of people like Galen Clark and John Muir.

Yosemite is one of the largest and least fragmented habitat blocks in the Sierra Nevada, and the park supports a diversity of plants and animals. The park has an elevation range from 2,127 to 13,114 feet (648 to 3,997 m) and contains five major vegetation zones: chaparral/oak woodland, lower montane, upper montane, subalpine, and alpine. Of California's 7,000 plant species, about 50% occur in the Sierra Nevada and more than 20% within Yosemite. There is suitable habitat or documentation for more than 160 rare plants in the park, with rare local geologic formations and unique soils characterizing the restricted ranges many of these plants occupy.

The geology of the Yosemite area is characterized by granitic rocks and remnants of older rock. About 10 million years ago, the Sierra Nevada was uplifted and then tilted to form its relatively gentle western slopes and the more dramatic eastern slopes. The uplift increased the steepness of stream and river beds, resulting in formation of deep, narrow canyons. About 1 million years ago, snow and ice accumulated, forming glaciers at the higher alpine meadows that moved down the river valleys. Ice thickness in Yosemite Valley may have reached 4,000 feet (1,200 m) during the early glacial episode. The downslope movement of the ice masses cut and sculpted the U-shaped valley that attracts so many visitors to its scenic vistas today.

Fast Fact of Yosemite National Park:

where is Yosemite National Park:

Central California's Sierra Nevada mountain range

Yosemite National Park Location:

Tuolumne, Mariposa, & Madera counties, California, USA

Nearest City of Yosemite National Park:

Mariposa, California

Yosemite National Park Coordinates:

37°44′43″N 119°35′54″W

Yosemite National Park Area:

761,268 acres (308,074 ha)

Yosemite Map:

Geography of the Yosemite Area:

Yosemite National Park is located in the central Sierra Nevada of California. It takes approximately 4 hours to drive to the park from San Francisco, approximately 6 hours from Los Angeles, and 7 hours from San Bernardino. Three wilderness areas are adjacent to Yosemite: the Ansel Adams Wilderness to the southeast, the Hoover Wilderness to the northeast, and the Emigrant Wilderness to the north.

The 1,189 sq mi (3,080 km2) park is roughly the size of the U.S. state of Rhode Island and contains thousands of lakes and ponds, 1,600 miles (2,600 km) of streams, 800 miles (1,300 km) of hiking trails, and 350 miles (560 km) of roads. Two federally designated Wild and Scenic Rivers, the Merced and the Tuolumne, begin within Yosemite's borders and flow westward through the Sierra foothills, into the Central Valley of California. Annual park visitation exceeds 3.5 million, with most visitor use concentrated in the seven-square mile (18 km2) area of Yosemite Valley.

Yosemite Weather Forecast:

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Rocks and Erosion:

Almost all of the landforms in the Yosemite area are cut from the granitic rock of the Sierra Nevada Batholith (a batholith is a large mass of intrusive igneous rock that formed deep below the surface). About 5% of the park's landforms (mostly in its eastern margin near Mount Dana) are metamorphosed volcanic and sedimentary rocks. These rocks are called roof pendants because they were once the roof of the underlying granitic rock.

Erosion acting upon different types of uplift-created joint and fracture systems is responsible for creating the valleys, canyons, domes, and other features we see today. These joints and fracture systems do not move, and are therefore not faults. Spacing between joints is controlled by the amount of silica in the granite and granodiorite rocks; more silica tends to create a more resistant rock, resulting in larger spaces between joints and fractures.

Pillars and columns, such as Washington Column and Lost Arrow, are created by cross joints. Erosion acting on master joints is responsible for creating valleys and later canyons. The single most erosive force over the last few million years has been large alpine glaciers, which have turned the previously V-shaped river-cut valleys into U-shaped glacial-cut canyons (such as Yosemite Valley and Hetch Hetchy Valley). Exfoliation (caused by the tendency of crystals in plutonic rocks to expand at the surface) acting on granitic rock with widely spaced joints is responsible for creating domes such as Half Dome and North Dome and inset arches like Royal Arches.

Popular Features:

Yosemite Valley represents only one percent of the park area, but this is where most visitors arrive and stay. The Tunnel View is the first view of the Valley for many visitors and is extensively photographed. El Capitan, a prominent granite cliff that looms over Yosemite Valley, is one of the most popular rock climbing destinations in the world because of its diverse range of climbing routes in addition to its year-round accessibility. Granite domes such as Sentinel Dome and Half Dome rise 3,000 and 4,800 feet (910 and 1,500 m), respectively, above the valley floor.

The high country of Yosemite contains beautiful areas such as Tuolumne Meadows, Dana Meadows, the Clark Range, the Cathedral Range, and the Kuna Crest. The Sierra crest and the Pacific Crest Trail run through Yosemite, with peaks of red metamorphic rock, such as Mount Dana and Mount Gibbs, and granite peaks, such as Mount Conness. Mount Lyell is the highest point in the park, standing at 13,120 ft. The Lyell Glacier is the largest glacier in Yosemite National Park and is one of the few remaining in the Sierra Nevada today.

The park has three groves of ancient Giant Sequoia (Sequoiadendron giganteum) trees; the Mariposa Grove (200 trees), the Tuolumne Grove (25 trees), and the Merced Grove (20 trees). This species grows larger in volume than any other and is one of the tallest and longest-lived.

Water and Ice:

Tuolumne and Merced River systems originate along the crest of the Sierra Nevada in the park and have carved river canyons 3,000 to 4,000 feet (910 to 1,200 m) deep. The Tuolumne River drains the entire northern portion of the park, an area of approximately 680 square miles (1,800 km2). The Merced River begins in the park's southern peaks, primarily the Cathedral and Clark Ranges, and drains an area of approximately 511 square miles (1,320 km2).

Hydrologic processes, including glaciation, flooding, and fluvial geomorphic response, have been fundamental in creating landforms in the park. The park also contains approximately 3,200 lakes (greater than 100 m²), two reservoirs, and 1,700 miles (2,700 km) of streams, all of which help form these two large watersheds. Wetlands in Yosemite occur in valley bottoms throughout the park, and are often hydrologically linked to nearby lakes and rivers through seasonal flooding and groundwater movement. Meadow habitats, distributed at elevations from 3,000 to 11,000 feet (910 to 3,400 m) in the park, are generally wetlands, as are the riparian habitats found on the banks of Yosemite's numerous streams and rivers.

Yosemite is famous for its high concentration of waterfalls in a small area. Numerous sheer drops, glacial steps and hanging valleys in the park provide many places for waterfalls to exist, especially during April, May, and June (the snowmelt season). Located in Yosemite Valley, the Yosemite Falls is the highest in North America at 2,425-foot (739 m). Also in Yosemite Valley is the much lower volume Ribbon Falls, which has the highest single vertical drop, 1,612 feet (491 m). Perhaps the most prominent of the Yosemite Valley waterfalls is Bridalveil Fall, which is the waterfall seen from the Tunnel View viewpoint at the east end of the Wawona Tunnel. Wapama Falls in Hetch Hetchy Valley is another notable waterfall. Hundreds of ephemeral waterfalls also exist in the park.

All glaciers in the park are relatively small glaciers that occupy areas that are in almost permanent shade, such as north- and northeast-facing cirques. Lyell Glacier is the largest glacier in Yosemite (the Palisades Glaciers are the largest in the Sierra Nevada) and covers 160 acres (65 ha). None of the Yosemite glaciers are a remnant of the much, much larger Ice Age alpine glaciers responsible for sculpting the Yosemite landscape. Instead, they were formed during one of the neoglacial episodes that have occurred since the thawing of the Ice Age (such as the Little Ice Age). Climate change has reduced the number and size of glaciers around the world. Many Yosemite glaciers, including Merced Glacier, which was discovered by John Muir in 1871 and bolstered his glacial origins theory of the Yosemite area, have disappeared and most of the others have lost up to 75% of their surface area.

Climate of Yosemite National Park:

Yosemite has a Mediterranean climate, meaning most precipitation falls during the mild winter, and the other seasons are nearly dry (less than 3% of precipitation falls during the long, hot summers). Because of orographic lift, precipitation increases with elevation up to 8,000 feet (2,400 m) where it slowly decreases to the crest. Precipitation amounts vary from 36 inches (910 mm) at 4,000 feet (1,200 m) elevation to 50 inches (1,300 mm) at 8,600 feet (2,600 m). Snow does not typically persist on the ground until November in the high country. It accumulates all winter and into March or early April.

Mean daily temperatures range from 25 to 53 °F (-3.9 to 11.5 °C) at Tuolumne Meadows at 8,600 feet (2,600 m). At the Wawona Entrance (elevation 5,130 feet / 1,560 metres), mean daily temperature ranges from 36 to 67 °F (2 to 19 °C). At the lower elevations below 5,000 feet (1,500 m), temperatures are hotter; the mean daily high temperature at Yosemite Valley (elevation 3,966 feet / 1,209 metres) varies from 46 to 90 °F (8 to 32 °C). At elevations above 8,000 feet (2,400 m), the hot, dry summer temperatures are moderated by frequent summer thunderstorms, along with snow that can persist into July. The combination of dry vegetation, low relative humidity, and thunderstorms results in frequent lightning-caused fires as well.

At the park headquarters, with an elevation of 3,966 feet (1,209 m), January averages 37.7 °F (3.2 °C), while July averages 72.7 °F (22.6 °C), though in summer the nights are much cooler than the hot days. There are an average of 46 days with highs of 90 °F (32 °C) or higher and an average of 122 nights with freezing temperatures. Freezing temperatures have been recorded in every month of the year. The record high temperature was 115 °F (46 °C) on July 20, 1915, while the record low temperature was −6 °F (−21 °C) on January 2, 1924. Average annual precipitation is nearly 38 inches (965 mm), falling on 71 days. The wettest year was 1983 with 68.94 inches (1,751 mm) and the dryest year was 1976 with 14.84 inches (377 mm). The most precipitation in one month was 29.61 inches (752 mm) in December 1955 and the most in one day was 6.92 inches (176 mm) on December 23, 1955. Average annual snowfall is 65.6 inches (1.67 m). The snowiest year was 1967 with 154.9 inches (3.93 m). The most snow in one month was 140.8 inches (3.58 m) in January 1993.

Yosemite Valley:

Yosemite Valley is a glacial valley in Yosemite National Park in the western Sierra Nevada mountains of California, carved out by the Merced River. The valley is about 8 miles (13 km) long and up to a mile deep, surrounded by high granite summits such as Half Dome and El Capitan, and densely forested with pines. A multitude of streams including Tenaya, Illilouette and Bridalveil Creeks join in the valley, and flow out of the valley's mouth as the Merced River, which eventually flows to the Pacific Ocean. The valley is renowned for its natural beauty, and is widely regarded as the centerpiece of Yosemite National Park, attracting visitors from around the world.

The Valley is the main attraction in the park for the majority of visitors, and a bustling hub of activity during "tourist season", with an array of visitor facilities clustered in the middle. There are both hiking trail loops that stay within the valley and trailheads that lead to higher elevations, all of which afford glimpses of the park's many scenic wonders.

Description:

Yosemite Valley is located on the western slope of the Sierra Nevada mountains, 150 miles (240 km) due east of San Francisco. It stretches for 7.5 miles (11 km) in a roughly east-west direction, with an average width of about 1 mile (1.6 km).

Yosemite Valley represents only one percent of the park area, but this is where most visitors arrive and stay. More than half a dozen creeks tumble from hanging valleys at the top of granite cliffs that can rise 3000–4000 feet (900–1200 m) above the valley floor, which itself is 4000 ft (1200 m) above sea level. These streams combine into the Merced River, which flows out from the western end of the valley, down the rest of its canyon to the San Joaquin Valley. The flat floor of Yosemite Valley holds both forest and large open meadows, which provide breathtaking views of the surrounding crests and waterfalls.

Below is a description of these features, looking first at the walls above, moving west to east as a visitor does when entering the valley, then visiting the waterfalls and other water features, returning east to west with the flow of water.

The first view of Yosemite Valley many visitors see is the Tunnel View. So many paintings were made from a viewpoint nearby that the National Park Service named that viewpoint Artist Point.

The view from the lower (western) end of the Valley contains the great granite monolith El Capitan on the left, and Cathedral Rocks on the right with Bridalveil Fall. Just past this spot the Valley suddenly widens with the Cathedral Spires, then the pointed obelisk of Sentinel Rock to the south. Across the Valley on the northern side are the Three Brothers, rising one above the other like gables built on the same angle – the highest crest is Eagle Peak, with the two below known as the Middle and Lower Brothers.

To this point, the Valley has been curving gently to the left, to the north. Now a grand curve back to the right begins, with Yosemite Falls on the north, followed by the Royal Arches, topped by North Dome. Opposite to the south is Glacier Point, 3,200 feet (975 m) above the Valley floor. At this point the Valley splits into two, one section slanting northeast, with the other curving from south to southeast. Between them both, at the eastern end of the valley, is Half Dome, the most famous and most recognizable natural feature in the Sierra Nevada. Above and to the northeast of Half Dome is Cloud's Rest; at 9926 feet (3025 m), the highest point around Yosemite Valley.

Water:

Snow melting in the Sierra forms creeks and lakes. In the surrounding region, these creeks flow to the edge of the Valley to form cataracts and waterfalls.

A fan of creeks and forks of the Merced River take drainage from the Sierra crest and combine at Merced Lake. The Merced then flows down to the end of its canyon (Little Yosemite Valley), where it begins what is often called the Giant Staircase. The first drop is Nevada Fall, which drops 594 feet (181 m), bouncing off the granite slope below it. Below is Vernal Fall, 317 feet (97 m) high, one of the most picturesque waterfalls in the Valley. The Merced then descends rapids to meet Illilouette Creek, which drops from the valley rim to form Illilouette Fall. They combine at the base of the gorges that contain each stream, and then flow around the Happy Isles to meet Tenaya Creek at the eastern end of Yosemite Valley proper.

Tenaya Creek flows southwest from Tenaya Lake and down Tenaya Canyon, finally flowing between Half Dome and North Dome before joining the Merced River. The following falls tumble from the Valley rim to join it at various points:

• Yosemite Falls (2,425 ft) Upper Yosemite Fall (1,430 ft), the middle cascades (675 ft), and Lower Yosemite Fall (320 ft). (Yosemite Creek)
• Snow Creek Falls (2,140 ft)
• Sentinel Falls (1,920 ft)
• Ribbon Fall (1,612 ft)
• Royal Arch Cascade (1,250 ft)
• Lehamite Falls (1,180 ft)
• Staircase Falls (1,020 ft)
• Bridalveil Fall (620 ft). (Bridalveil Creek)
• Nevada Fall (594 ft)
• Silver Strand Falls (574 ft)
• Vernal Fall (318 ft)

Natural Yosemite Valley:

Geology of the Yosemite area:

The features in Yosemite Valley are made of granitic rock that was emplaced as plutons miles deep during the late Cretaceous. Over time the Sierra Nevada was uplifted and this rock was exposed at the surface where it was modified by erosion.

The oldest of these granitic rocks occur along the Merced River Gorge west of the valley and are thought to be 114 million years old. The El Capitan pluton intruded the valley forming most of the granitic rock that makes up much of the central part of the valley including Cathedral Rocks, Three Brothers and of course El Capitan. The youngest pluton of Yosemite Valley is the 87 million year old Half Dome granodiorite which makes up most of the rock seen at Glacier Point, the Royal Arches and its namesake Half Dome.

For the last 30 million years, glaciers have periodically filled much of the valley. The most current glaciation, the Wisconsinian was not, however, the most severe. Ice ages previous to the Wisconsinian were colder and lasted longer. Their glaciers were huge and covered nearly all the landmarks around Yosemite Valley except Half Dome, Eagle Peak, Sentinel Dome, and the top of El Capitan. Wisconsinian glaciers, however, only reached Bridalveil Fall in the valley. The glaciers widened the valley, but much of its width is in fact due to previous stream erosion and mass wasting along vertical joints in the valley's walls.

After the retreat of many of these glaciers, a stand of Lake Yosemite developed. The valley floor owes its flatness to sediment deposited by these stands (the last glaciers in the valley were small and did not remove much old lake sediment). The last stand of Lake Yosemite was about 5.5 miles (8.9 km) long and was impounded by a terminal moraine near the base of El Capitan. It was later filled by sediment, becoming a swampy meadow.

The parallel Tenaya Canyon and Little Yosemite Canyon glaciers were, at their largest, 2,000 feet (600 m) deep where they flowed into the Yosemite Valley near the base of Half Dome. They also formed Cloud's Rest behind Half Dome as an arête.

Near Glacier Point there is 2,000 feet (600 m) of mostly glacial sediment with at least six separate sequences of Lake Yosemite sediments. Here, huge and highly erosive pre-Wisconsinian glaciers are thought to be responsible for excavating the bedrock valley floor, and much smaller Wisconsinian glaciers were responsible for depositing glacial debris.

Ecology of Yosemite Valley:

The biological community on the floor of Yosemite Valley is a diverse one, with more than 400 species of grasses and wildflowers and thousands of species of insects having been identified there. At the most general level, the valley can be classified as a dry Yellow pine forest with a number of large open meadows. Plant and animal species that make up a significant part of this natural community include:

Trees – Ponderosa Pine, Lodgepole Pine, Sugar Pine, White Fir, Incense-cedar, California black oak, Interior live oak, Coast Douglas-fir, California laurel, Bigleaf Maple, Scouler's Willow, Pacific Dogwood, White alder, Western Balsam Poplar

Shrubs – Whiteleaf manzanita, Mountain misery, Western azalea, American dogwood, Buckbrush, Deer brush, Sierra gooseberry

Wildflowers – Indian pink, Soap plant, California Poppy, Miner's lettuce, Purple Chinese Houses, Purple milkweed, Pacific Starflower, Western buttercup, Pineapple weed

Mammals – California Ground Squirrel, Western Gray Squirrel, Chickaree, Mule Deer, American Black Bear, Bobcat, Coyote

Birds – Dark-eyed Junco, Mountain Chickadee, Black-headed Grosbeak, White-headed Woodpecker, Steller's Jay, American Dipper, Common Raven

Reptiles – Gilbert's Skink, Northern Alligator Lizard, Rattlesnake

Amphibians – Sierra Nevada Salamander

Hiking:

Several trails lead out of the Valley, including

• The John Muir Trail --- running 212 miles (341 km) to Mount Whitney
• The Mist Trail --- with views of Vernal Falls and Nevada Fall
• The Four Mile Trail --- leading to Glacier Point.
• The Yosemite Falls Trail --- to the top of Yosemite Falls

Ecology of the Sierra Nevada:

Habitats:

With its scrubby sun-baked chaparral, stately groves of pine, fir, and sequoia, and expanses of alpine woodlands and meadows, Yosemite National Park preserves a Sierra Nevada landscape as it prevailed before Euro-American settlement. In contrast to surrounding lands, which have been significantly altered by logging, the park still contains some 225,510 acres (91,260 ha) of old-growth forest. Taken together, the park's varied habitats support over 250 species of vertebrates, which include fish, amphibians, reptiles, birds, and mammals.

Along much of Yosemite's western boundary, habitats are dominated by mixed coniferous forests of Ponderosa Pine, Sugar Pine, Incense-cedar, White Fir, Douglas Fir, and a few stands of Giant Sequoia, interspersed by areas of Black Oak and Canyon Live Oak. A relatively high diversity of wildlife species are supported by these habitats, because of relatively mild, lower-elevation climate and the mixture of habitat types and plant species. Wildlife species typically found in these habitats include American black bear, Bobcat, Cougar, Gray fox, Mule deer, Mountain kingsnake, Gilbert's skink, White-headed Woodpecker, Brown Creeper, Spotted Owl, and a wide variety of bat species. In the case of bats, large snags are important as roost sites.

Going higher in elevation, the coniferous forests become purer stands of Red Fir, Western White Pine, Jeffrey Pine, Lodgepole Pine, and the occasional Foxtail pine. Fewer wildlife species tend to be found in these habitats, because of their higher elevation and lower complexity. Species likely to be found include Golden-mantled Ground Squirrel, Chickaree, Fisher, Steller's Jay, Hermit Thrush, and Northern Goshawk. Reptiles are not common, but include Rubber Boa, western fence lizard, and Northern Alligator Lizard.

As the landscape rises, trees become smaller and more sparse, with stands broken by areas of exposed granite. These include Lodgepole Pine, Whitebark Pine, and Mountain Hemlock that, at highest elevations, give way to vast expanses of granite as treeline is reached. The climate in these habitats is harsh and the growing season is short, but species such as Pika, Yellow-bellied Marmot, White-tailed Jackrabbit, Clark's Nutcracker, and Black Rosy Finch are adapted to these conditions. Also, the treeless alpine habitats are the areas favored by Sierra Nevada Bighorn Sheep. This species, however, is now found in the Yosemite area only around Tioga Pass, where a small, reintroduced population exists.

At a variety of elevations, meadows provide important, productive habitat for wildlife. Animals come to feed on the green grasses and use the flowing and standing water found in many meadows. Predators, in turn, are attracted to these areas. The interface between meadow and forest is also favored by many animal species because of the proximity of open areas for foraging and cover for protection. Species that are highly dependent upon meadow habitat include Great Grey Owl, Willow Flycatcher, Yosemite Toad, and Mountain Beaver.

Management issues:

Despite the richness of high-quality habitats in Yosemite, the Brown Bear, California Condor, and Least Bell's Vireo have become extinct in the park within historical time, and another 37 species currently have special status under either California or federal endangered species legislation. The most serious current threats to Yosemite's wildlife and the ecosystems they occupy include loss of a natural fire regime, exotic species, air pollution, habitat fragmentation, and climate change. On a more local basis, factors such as road kills and the availability of human food have affected some wildlife species.

The black bears of Yosemite were once famous for breaking into parked cars to steal food. They were also an encouraged tourist sight for many years at the park's garbage dumps, where bears congregated to eat park visitors' garbage and tourists gathered to photograph the bears. Increasing encounters between bears and humans and increasing damage to property led to an aggressive campaign to discourage bears from relying on human food or interacting with people and their property. The open-air dumps were closed; all trash receptacles were replaced with bear-proof receptacles; all campgrounds were equipped with bear-proof food lockers so that people would not leave food in their vehicles, which were easy targets for the powerful and resourceful bears. Because bears who show aggression towards people usually are eventually destroyed, park personnel have continued to come up with innovative ways to have bears associate humans and their property with unpleasant experiences, such as being hit with rubber bullets. Today, about 30 bears a year are captured and ear-tagged and their DNA is sampled so that, when bear damage occurs, rangers can ascertain which bear is causing the problem.

Increasing ozone pollution is causing tissue damage to the massive Giant Sequoia trees in the park. This makes them more vulnerable to insect infestation and disease. Since the cones of these trees require fire-touched soil to germinate, historic fire suppression has reduced these trees' ability to reproduce. The current policy of setting prescribed fires is expected to help the germination issue.

Yosemite National Park has documented more than 130 non-native plant species within park boundaries. These non-native plants were introduced into Yosemite following the migration of early Euro-American settlers in the late 1850s. Natural and human-caused disturbances, such as wildland fires and construction activities, have contributed to a rapid increase in the spread of non-native plants. A number of these species aggressively invade and displace the native plant communities, resulting in impacts on the park's resources. Non-native plants can bring about significant changes in park ecosystems by altering the native plant communities and the processes that support them. Some non-native species may cause an increase in the fire frequency of an area or increase the available nitrogen in the soil that may allow more non-native plants to become established. Many non-native species, such as Yellow Star Thistle (Centaurea solstitialis), are able to produce a long tap root that allows them to out-compete the native plants for available water.

Bull Thistle (Cirsium vulgare), Common Mullein (Verbascum thapsus), and Klamath Weed (Hypericum perforatum) have been identified as noxious pests in Yosemite since the 1940s. Additional species that have been recognized more recently as aggressive and requiring control are Yellow Star Thistle (Centaurea solstitialis), Sweet Clover (Melilot spp.), Himalayan Blackberry (Rubus armeniacus), Cut-leaved Blackberry (Rubus laciniatus) and Large Periwinkle (Vinca major).

Activities at Yosemite Valley:

Yosemite Valley is open year-round, but much of the remaining park is closed because of snow in late autumn and re-opens in mid to late spring. Open-air tours around Yosemite Valley and the Mariposa Grove of Giant Sequoias are available. Many people enjoy short walks and longer hikes to waterfalls in Yosemite Valley, or walks amongst Giant Sequoias in the Mariposa, Tuolumne, or Merced Groves. Others like to drive or take a tour bus to Glacier Point (summer-fall) to see a spectacular view of Yosemite Valley and the high country, or drive along the scenic Tioga Road to Tuolumne Meadows (summer-fall) and go for a walk or hike.

Most park visitors stay just for the day, and only visit locations within Yosemite Valley that are easily accessible by automobile. There is a US$20 per automobile user fee to enter the park. Traffic congestion in the valley is a serious problem during peak season, in summer. A free shuttle bus system operates year-round in the valley, and park rangers encourage people to use this system since parking within the valley during the summer is often nearly impossible to find.

In addition to exploring the natural features of the park, visitors can also learn about the natural and cultural history of Yosemite Valley at a number of facilities in the valley: the Yosemite Valley Visitor Center, the adjoining Yosemite Museum, and the Nature Center at Happy Isles. There are also two National Historic Landmarks: the LeConte Memorial Lodge (Yosemite's first public visitor center), and the world-famous Ahwahnee Hotel. Camp 4 was added to the National Register of Historic Places in 2003.

Hiking:

Over 800 miles (1,300 km) of trails are available to hikers — anything from the easy stroll, to the grueling hikes up several park mountains, to multiple-day backpack trips.

The park can be divided into 5 sections for the day-user—Yosemite Valley, Wawona/Mariposa Grove/ Glacier Point, Tuolumne Meadows, Hetch Hetchy, and Crane Flat/White Wolf. Numerous books describe park trails, and free information is available from the Park Service in Yosemite. Park rangers encourage visitors to experience portions of the park in addition to Yosemite Valley.

Between late spring and early fall, much of the park is open to multiple-day backpack trips. All overnight trips into the back country require a wilderness permit and most require approved bear-resistant food storage.

Driving destinations:

While some locations in Yosemite require hiking, other locations can be observed via automobile transportation. Driving locations also allow guests to observe the night sky in locations other than their campsite or lodge. All of the roads in Yosemite are scenic, but the most famous is the Tioga Road, typically open from late May or early June through November.

As an alternative to driving, bicycles are allowed on the roads. However, bicycles are only allowed off-road on 12 miles (19 km) of paved trails in Yosemite Valley itself; mountain biking is not allowed.

List of Yosemite destinations:

A list of Yosemite destinations includes hiking trails and things to see:

Near the Yosemite Valley:

• Yosemite Falls
• Bridalveil Falls
• Mirror Lake
• Mist Trail
• Half Dome

Near Glacier Point:

• Panorama Trail from Glacier Point
• McGurk Meadow
• Ostrander Lake
• Mono Meadow
• Taft Point
• Sentinel Dome

Near Wawona:

• Chilnualna Falls
• Alder Creek
• Mariposa Grove

Other hiking:

• Wapama Falls
• Rancheria Falls
• Soda Springs
• Dog Lake
• Lembert Dome
• Glen Aulin
• Elizabeth Lake
• Cathedral Lakes
• John Muir Trail
• Mono Pass
• Gaylor Lakes
• Vogelsang

Things to see at in Yosemite Park:

Popular things to look at in Yosemite Park include:

Waterfalls:

The following is a list of Yosemite waterfalls, including ephemeral falls:

• Bridalveil Fall 620 feet (190 m)
• Chilnualna Falls 690 feet (210 m)
• Horsetail Fall 2,100 feet (640 m)
• Illilouette Fall 370 feet (110 m)
• Lehamite Falls 1,180 feet (360 m)
• Nevada Fall 594 feet (181 m)
• Pywiack Cascade 600 feet (180 m)
• Quaking Aspen Falls 25 feet (7.6 m)
• Ribbon Fall 1,612 feet (491 m)
• Royal Arch Cascade 1,250 feet (380 m)
• Sentinel Fall 1,920 feet (590 m)
• Silver Strand Falls 574 feet (175 m)
• Snow Creek Falls 2,140 feet (650 m)
• Staircase Falls 1,020 feet (310 m)
• Three Chute Falls 80 feet (24 m)
• Tueeulala Falls 840 feet (260 m)
• Vernal Fall 317 feet (97 m)
• Wapama Falls 1,700 feet (520 m)
• Waterwheel Falls 300 feet (91 m)
• Wildcat Falls 630 feet (190 m)
• Yosemite Falls 2,425 feet (739 m)

Rock formations:

• Half Dome
• El Capitan
• Cathedral Rocks
• The Three Brothers
• Sentinel Rock
• Yosemite Point
• Glacier Point

Giant Sequoias:

For information about the tree, see Sequoiadendron. Groves of the trees include:

• Mariposa Grove
• Tuolumne Grove
• Merced Grove

Scenic vistas:

• Glacier Point
• Olmsted Point
• Tunnel View
• El Portal View
• O'Shaughnessy Dam
• Cascade View
• Pothole Dome
• Lembert Dome
• Yosemite Valley itself contains many views

Climbing:

Rock climbing is an important part of Yosemite. Camp 4, a walk-in campground in Yosemite Valley, was instrumental in the development of rock climbing as a sport, and is listed on the National Register of Historic Places. Climbers can generally be spotted in the snow-free months on anything from ten-foot-high (3 m) boulders to the 3,300-foot (1.0 km) face of El Capitan. Classes are offered by numerous groups on rock climbing.

Winter activities:

Many of the roads in the park close because of heavy snow in winter; however, Yosemite Valley is open all year long. Downhill skiing is available at the Badger Pass Ski Area—the oldest downhill skiing area in California, offering downhill skiing from mid-December through early April. Much of the park is open to cross-country skiing and snowshoeing, with several backcountry ski huts open for use. Wilderness permits are required for backcountry overnight ski trips.

The Bracebridge dinner is an annual holiday event, held since 1927 at the Ahwahnee Hotel, inspired by Washington Irving's descriptions of Squire Bracebridge and English Christmas traditions of the 18th century in his Sketch Book. Between 1929 and 1973, the show was organized by Ansel Adams.

Other:

Bicycle rentals are available in Yosemite Valley spring through fall. Over 12 miles (19 km) of paved bike paths are available in Yosemite Valley. In addition, bicyclists can ride on regular roads. Helmets are required by law for children under 18 years of age. Off-trail riding and mountain biking are not permitted in Yosemite National Park.

Water activities are plentiful during warmer months. Rafting can be done through the Yosemite Valley on the Merced River. There is also a swimming pool available at Curry Village

In 2010, Yosemite National Park was honored with its own quarter under the America the Beautiful Quarters program.

Yosemite Falls:

Yosemite Falls is the highest measured waterfall in North America. Located in Yosemite National Park in the Sierra Nevada of California, it is a major attraction in the park, especially in late spring when the water flow is at its peak.

The total 2,425 feet (739 m) from the top of the upper falls to the base of the lower falls qualifies Yosemite Falls as the sixth highest waterfall in the world, though with the recent discovery of Gocta Cataracts, it appears on some lists as seventh.

Sections:

Although often referred to as a "two-stage drop", the falls actually consist of three sections:

Upper Falls: The 1,430-foot (440 m) plunge alone is among the twenty highest waterfalls in the world. Trails from the valley floor and down from other park areas outside the valley lead to both the top and base of Upper Yosemite Falls. The upper fall is formed by the swift waters of Yosemite Creek, which, after meandering through Eagle Creek Meadow, hurl themselves over the edge of a hanging valley in a spectacular and deafening show of force.

Middle Cascades: Between the two obvious main plunges there are a series of five smaller plunges collectively referred to as the Middle Cascades. Taken together these account for a total drop of 675 feet (206 m), more than twice the height of the Lower Falls. Because of the narrow, constricted shape of the gorge in which these drops occur and the lack of public access, they are rarely noted. Most viewpoints in the valley miss them entirely. Several vantage points for the cascades are found along the Yosemite Falls trail. Several hikers climbing down from the trail towards the cascades have required an expensive helicopter rescue due to steep and slippery terrain and features.

Lower Falls: The final 320-foot (98 m) drop adjacent to an accessible viewing area, provides the most-used viewing point for the waterfalls. Yosemite Creek emerges from the base of the Lower Falls and flows into the Merced River nearby. Like many areas of Yosemite the plunge pool at the base of the Lower Falls is surrounded by dangerous jumbles of talus made even more treacherous by the high humidity and resulting slippery surfaces.

In years of little snow, the falls may actually cease flowing altogether in late summer or fall. A very small number of rock climbers have taken the opportunity to climb the normally inaccessible rock face beneath the falls, although this is an extraordinarily dangerous undertaking; a single afternoon thunderstorm could restart the falls, sweeping the climbers off the face.

The Lower Falls are easily accessible near the Yosemite Lodge in Yosemite Valley. The top of the Upper Falls may be reached via a steep, strenuous, and usually crowded 3.5 miles (5.6 km) hike beginning near Camp 4. The Upper Falls may also be reached via several routes from the Tioga Road to the north.

The Ahwahneechee Legend:

The Ahwahneechee people of Yosemite Valley called the waterfall "Cholock" and believed that the plunge pool at its base was inhabited by the spirits of several witches, called the Poloti. An Ahwaneechee folktale describes a woman going to fetch a pail of water from the pool, and drawing it out full of snakes. Later that night, after the woman had trespassed into their territory, the spirits caused the woman's house to be sucked into the pool by a powerful wind, taking the woman and her newborn baby with her.

Ecology of the Sierra Nevada:

The ecology of the Sierra Nevada, located in the U.S. state of California, is diverse and complex: the plants and animals are a significant part of the scenic beauty of the mountain range. The combination of climate, topography, moisture, and soils influences the distribution of ecological communities across an elevation gradient from 1,000 feet (300 m) to over 14,000 feet (4,300 m). Biotic zones range from scrub and chaparral communities at lower elevations, to subalpine forests and alpine meadows at the higher elevations. Elevational contours characterized by a particular biome and ecosystem are often described as a series of belts that follow the length of the Sierra Nevada. There are many hiking trails, paved and unpaved roads, and vast public lands in the Sierra Nevada for exploring the many different biomes and ecosystems.

The western and eastern Sierra Nevada have substantially different species of plants and animals, because the east lies in the rain shadow of the crest. The plants and animals in the east are thus adapted to much drier conditions.

The altitudes listed for the biotic zones are for the central Sierra Nevada. The climate across the north-south axis of the range varies somewhat: the boundary elevations of the biotic zones move by as much as 1,000 feet (300 m) from the north end to the south end of the range.

Western biotic zones:

Foothill Woodland and Chaparral Zone:

The lowest-elevation biotic zone in the Sierra Nevada is found along the boundary with the Central Valley. This zone, stretching in elevation from 1000 feet (300 m) to 3000 feet (900 m), is the foothill woodland zone, an area that is hot and dry in the summer with very little or no snow in the winter. Plants within this zone include chamise, ceanothus, manzanita, blue oak, interior live oak, and Gray Pine. Animals typical of this zone include black bear, ringtail cat, coyote, gray squirrel, bobcat, California Mule Deer, and skunk. In the foothills of the northern portion of the Sierra Nevada, toyon and chamise often co-dominate certain open serpentine chaparral communities.

Sierra Nevada lower montane forest:

Beginning near the 3,000 foot (900 m) elevation, the hot, dry summers and cool, moist winters of the Mediterranean climate give rise to the lower montane forest zone. This zone is also known as the Yellow pine forest zone. The accumulation of several feet of snow during the winter is not uncommon and can stay on the ground for several months. The diversity of tree species found in this zone make this a beautiful and interesting forest to explore. The indicator species for the lower montane forest are the Ponderosa Pine and the Jeffrey Pine: the Ponderosa Pine generally occurs on the west side of the Sierra, while the Jeffrey Pine occurs on the east. The lower montane forests also include trees such as California black oak, Sugar Pine, Incense-cedar, and White Fir. The Giant Sequoia groves of the Sierra Nevada are also found within this biotic zone. Animals that may be found in this zone include the Dark-eyed Junco, Mountain Chickadee, Western gray squirrel, Mule deer, and American black bear. The lower montane forest can be seen in Yosemite Valley and along the Wawona, Hetch Hetchy, and Big Oak Flat Roads.

Upper Montane Forest:

The upper montane forest begins at higher elevations near 7,000 feet (2,100 m), where the montane climate is characterized by short, moist, cool summers and cold, wet winters. Snow begins to fall in November and may accumulate to depths up to six feet (1.8 m) and remain until June. Pure stands of Red Fir and Lodgepole Pine (the indicator species) are typical of this forest. Jeffrey Pine, which has bark that smells like vanilla, and the picturesque Western Juniper can also be found in this zone. Wildflowers bloom in meadows from June through August. Common animals in this zone include the Hermit Thrush, Dusky Grouse (Dendragapus obscurus), Great Grey Owl, Golden-mantled Ground Squirrel, and (more rarely) the Marten. Upper montane forests may be viewed from the Tioga Pass Road east of Crane Flat, Glacier Point Road, and State Route 108.

Sierra Nevada Subalpine Forest:

The upper montane forest is replaced by the subalpine forest near 9,000 feet (2750 m), where the climate is cooler with an even shorter growing season due to long, cold, and snowy winters. Accumulations of three to nine feet (1 to 2.5 m) of snow are typical. The most common tree in the subalpine forest is the Whitebark pine. The Western White Pine, Mountain Hemlock, and Lodgepole Pine are also found in this forest with many subalpine meadows that flower from July through August. Many species live in, or are transient in, this zone, including Clark's Nutcracker. This zone can be seen from the Tuolumne Meadows area east to Tioga Pass.

Alpine Zone:

The alpine zone begins near the 9,500 foot (2,900 m) elevation and is easily distinguished as it is above tree line. No trees grow in this zone due to the harsh climatic conditions. Short, cool summers with long, cold, and snowy winters are typical at these elevations. Many exposed granitic outcroppings, talus slopes, and boulder fields limit the amount of vegetation that grows here. The herbaceous plants need to flower and produce their seeds quickly during the short, frost-free period of summer. Some animal species that are adapted to this zone include the American Pika, Belding's Ground Squirrel, the Yellow-Bellied Marmot, and the endangered Sierra Nevada Bighorn Sheep. This zone can be viewed up close by hiking or climbing into the high elevations of the Sierra.

Eastern biotic zones:

The four highest eastern biotic zones are the same as the western zones, but at a higher elevation, due to less precipitation:

1. Alpine zone: 12,000 feet (3700 m) and above
2. Subalpine forest: 10,500 feet (3200 m) - 12,000 feet (3700 m)
3. Upper montane forest: 9,000 feet (2700 m) - 10,500 feet (3200 m)
4. Lower montane forest: 7,000 feet (2100 m) - 9,000 feet (2700 m) (heavily dominated by Jeffrey Pines).

In the Owens Valley, the Foothill Woodland Zone is replaced by a Pinyon-Juniper Woodland Zone, characterized by Single-leaf Pinyon Pines, Sierra Junipers. The underbrush contains Big Sagebrush (Artemisia tridentata) and blackbrush (Coleogyne ramosissima). Jeffrey Pines may occur along streams. Notable animals in this zone include the Pinyon Jay and the Desert Bighorn Sheep. The Pinyon-Juniper Woodland Zone extends down to 5,000 feet (1500 m) elevation.

Below 5,000 feet (1500 m), there is not enough precipitation to support trees. The zones below this elevation are the Sagebrush Scrub Zone, Saltbush Scrub Zone, and the Alkali Sink Zone. These zones are distinguished by soil salinity.

Threats:

Exotic Plants in Yosemite National Park:

Yosemite National Park has documented more than 130 non-native plant species within park boundaries. These non-native plants were introduced into Yosemite following the migration of early settlers in the late 1850s. Natural and human-caused disturbances, such as wildland fires and construction activities, have contributed to a rapid increase in the spread of non-native plants. A number of these species aggressively invade and displace the native plant communities, resulting in impacts on the park's resources. Non-native plants can bring about significant changes in park ecosystems by altering the native plant communities and the processes that support them. Some non-native species may cause an increase in the fire frequency of an area or increase the available nitrogen in the soil that may allow more non-native plants to become established. Many non-native species, such as yellow starthistle (Centaurea solstitialis), are able to produce a long tap root that allows them to out-compete the native plants for available water.

Bull thistle (Cirsium vulgare), Common Mullein (Verbascum thapsus), and Klamath weed (Hypericum perforatum) have been identified as noxious pests in Yosemite since the 1940s. Additional species that have been recognized more recently as aggressive and requiring control are yellow starthistle, sweet clovers (Melilotus spp.), Himalayan blackberry (Rubus discolor), Cut-leaved blackberry (Rubus laciniatus) and periwinkle (Vinca major).

Lodgepole Needle Miner:

The Lodgepole Needle Miner (Coleotechnites milleri) is an insect, endemic to the upper Tuolumne and Merced River watersheds of Yosemite National Park and one small headwaters drainage of the San Joaquin River (Sierra National Forest). It lives mostly within the needles of Lodgepole Pine for two years, emerging as a little gray moth for a few weeks in July of odd-numbered years. This keeps any predators from becoming effective control agents and allows populations to escalate rapidly. While regular prehistoric outbreaks of Lodgepole Needle Miners have been confirmed through dendrochronology, historic records document outbreaks from 1903 to 1921, 1933 to 1941, and 1947 to 1963.

Extensive stands of "Ghost Forest" and jackstrawed trees are still conspicuous throughout Sierra Nevada. Annual monitoring of Lodgepole Needle Miner density began in 1966, and 28 permanent plots are scattered north of the Cathedral Range. The current outbreak began in 1973 and has been sweeping around the south side of the Cathedral Range, arriving at Sunrise High Sierra Camp in 2001. The Ghost Forest which was evident at the crest between Tenaya Lake and Tuolumne Meadows in the late 1970s was noticeably reforested by 2000. Lodgepole Needle Miner defoliation currently extends over approximately 40,000 acres (162 km²), with nearly 10,000 acres (40 km²) of low to high mortality each year.

While lightning fires are frequent in lodgepole pine communities, they usually remain small, with estimated fire return intervals at Yosemite National Park that are long (relative to most other forest types). Thus, fire suppression activities are thought to have had little influence upon species composition, structure, fuels, and natural processes in lodgepole forests. Also, in comparison with Rocky Mountains lodgepole pine forests, fire plays a smaller role, and so the needle miner assumes greater importance in lodgepole pine forest population dynamics in the Sierra Nevada. However, Rocky Mountain lodepole forest dynamics are also heavily influenced by insect outbreaks, primarily bark beetles.

Special-Status Species:

There are at least 1,300 vascular plant species in the Sierra Nevada, along with numerous bryophytes and lichens. There are at least 450 species of vertebrate animals. A total of 135 plant species in the Sierra Nevada have status as Threatened, Endangered, or Sensitive.

Plants that are Federal species of concern (former Category 2 species) under the Federal Endangered Species Act include:

1. Three-bracted Onion (Allium tribracteatum),
2. Yosemite Woolly Sunflower (Eriophyllum nubigenum),
3. Congdon's Lomatium (Lomatium congdonii),
4. Tiehm's Rock-cress (Arabis tiehmii),
5. Slender-stemmed Monkeyflower (Mimulus filicaulis), and
6. Bolander's Clover (Trifolium bolanderi).

Although Category 2 was abolished in 1996, species of concern is an informal term that refers to those species that might be declining or be in need of concentrated conservation actions to prevent decline. Therefore, these six species continue to be evaluated and managed by the National Park Service.

Four state-listed rare plant species are considered restricted and limited throughout all or a significant portion of their range, and may represent disjunct populations at the extreme end of their range:

• Yosemite Onion (Allium yosemitense),
• Tompkin's Sedge (Carex tompkinsii),
• Congdon's Woolly Sunflower (Eriophyllum congdonii), and
• Congdon's Lewisia (Lewisia congdonii).

Endangered or threatened species of animals that occur in the Sierra Nevada include:

• Sierra Nevada Bighorn Sheep
• California Condor
• Southwestern Willow Flycatcher
• Paiute Cutthroat Trout
• Lahontan Cutthroat Trout
• Owens Tui chub (Gila bicolor)

Wetlands:

Wetlands in the Sierra Nevada occur in valley bottoms throughout the range, and are often hydrologically linked to nearby lakes and rivers through seasonal flooding and groundwater movement. Meadow habitats, distributed at elevations from 3,000 to 11,000 feet (910 to 3,400 m), are generally wetlands, as are the riparian habitats found on the banks of numerous streams and rivers.

The Sierra contain three major types of wetland:

1. Riverine,
2. Lacustrine, and
3. Palustrine

Each of these types of wetlands varies in geographic distribution, duration of saturation, vegetation community, and overall ecosystem function. All three types of wetlands provide rich habitat for plant and animal species, delay and store seasonal floodwaters, minimize downstream erosion, and improve water quality.

Riverine wetlands are found within river and stream channels and are strongly influenced by seasonal runoff patterns. When inundated, riverine wetlands provide habitat for water-tolerant plants such as willows, and aquatic animals such as tadpoles and immature fish.

Lacustrine wetlands generally occur on river floodplains and along lakeshores and are influenced by seasonal variations in groundwater levels. These wetlands are rare in the mountain range, but support an abundance of warm-water loving plant and animal species.

Palustrine wetlands are typically distinguished from riverine and lacustrine systems by the presence of very dense covers of trees, shrubs, or emergent plants. This wetland type includes wet meadows, densely vegetated riparian habitats, and shallow ponds. They provide cover and forage for wildlife traveling between upland and aquatic habitats.

Since the 1970s the United States has made substantial progress toward protecting and restoring wetland habitats. All federal land in the Sierra Nevada complies with a 1990 Presidential Executive Order that mandates 'no net loss' of wetlands, and requires federal agencies to map and protect all existing wetlands.

In 1996 the National Fish and Wildlife Service delineated and classified some of the wetlands of the Sierra Nevada, including all of Yosemite National Park. This was performed through an analysis of aerial photographs and topographic maps, as a part of the National Wetlands Inventory Web Site (NWI). The NWI maps have not been rigorously ground-truthed and only delineate wetlands larger than five acres (20,000 m²) in size.

The National Park Service restores to natural conditions wetlands that have been drained or filled in the past. Most recently in Yosemite Valley, the Cook's Meadow restoration project involved filling old drainage ditches that were draining the meadow and removing an old roadbed that was inhibiting water flow. These actions are currently being monitored with vegetation transects and mapping of surface water to determine how successful the project was in restoring the wetland.

Geology of the Yosemite Area:

Tectonic and volcanic activity:

The area of the park was astride a passive continental margin during the Precambrian and early Paleozoic. Sediment was derived from continental sources and was deposited in shallow water. These rocks have since been metamorphosed.

Heat generated from the Farallon Plate subducting below the North American Plate led to the creation of an island arc of volcanoes on the west coast of proto-North America between the late Devonian and Permian periods. Later volcanism in the Jurassic intruded and covered these rocks in what may have been magmatic activity associated with the early stages of the creation of the Sierra Nevada Batholith. 95% of these rocks were eventually removed by uplifted-accelerated erosion.

The first phase of regional plutonism started 210 million years ago in the late Triassic and continued throughout the Jurassic to about 150 million years before present (BP). Around the same time, the Nevadan orogeny built the Nevadan mountain range (also called the Ancestral Sierra Nevada) to a height of 15,000 feet (4,600 m). This was directly part of the creation of the Sierra Nevada Batholith, and the resulting rocks were mostly granitic in composition and emplaced about 6 miles (9.7 km) below the surface. The second major pluton emplacement phase lasted from about 120 million to 80 million years ago during the Cretaceous. This was part of the Sevier orogeny.

Starting 20 million years ago (in the Cenozoic) and lasting until 5 million years ago, a now-extinct extension of Cascade Range volcanoes erupted, bringing large amounts of igneous material in the area. These igneous deposits blanketed the region north of the Yosemite region. Volcanic activity persisted past 5 million years BP east of the current park borders in the Mono Lake and Long Valley areas.

Uplift and erosion:

Starting 10 million years ago, vertical movement along the Sierra fault started to uplift the Sierra Nevada. Subsequent tilting of the Sierra block and the resulting accelerated uplift of the Sierra Nevada increased the gradient of western-flowing streams. The streams consequently ran faster and thus cut their valleys more quickly. Additional uplift occurred when major faults developed to the east, especially the creation of Owens Valley from Basin and Range-associated extensional forces. Uplift of the Sierra accelerated again about two million years ago during the Pleistocene.

The uplifting and increased erosion exposed granitic rocks in the area to surface pressures, resulting in exfoliation (responsible for the rounded shape of the many domes in the park) and mass wasting following the numerous fracture joint planes (cracks; especially vertical ones) in the now solidified plutons. Pleistocene glaciers further accelerated this process and the larger ones transported the resulting talus and till from valley floors.

Numerous vertical joint planes controlled where and how fast erosion took place. Most of these long, linear and very deep cracks trend northeast or northwest and form parallel, often regularly spaced sets. They were created by uplift-associated pressure release and by the unloading of overlying rock via erosion.

Sculpting by glaciers:

A series of glaciations further modified the region starting about 2 to 3 million years ago and ending sometime around 10,000 BP. At least four major glaciations 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. A Sherwin-age glacier was almost surely responsible for the major excavation and shaping of Yosemite Valley and other canyons in the area.

 

Glacial systems reached depths of up to 4,000 feet (1,200 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 (97 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 Russel (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 the 5.5 miles (9 km) long Lake Yosemite (a shallow lake that periodically covered much of the floor of Yosemite Valley).

Yosemite Hotels:

Ahwahnee Hotel
Wawona Hotel

Yosemite National Park Pictures:

Information about Yosemite National Park, Yosemite Falls, Yosemite Weather, Yosemite Valley, Hiking, Ecology of the Sierra Nevada, Yosemite Lodging, where is Yosemite National Park, Yosemite Map, Yosemite Weather Forecast, Activities at Yosemite Valley, List of Yosemite destination, Things to see at in Yosemite Park, Climate of Yosemite National Park, Alpine Zone, Yosemite Hotels, Yosemite National Park Pictures and much more

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