Explore Geology
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National Park


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Yosemite National Park, California

Yosemite National Park embraces a vast tract of scenic wildlands set aside in 1890 to preserve a portion of the Sierra Nevada mountains that stretches along California's eastern flank. The park ranges from 2,000 feet above sea level to more than 13,000 feet and offers three

major features:
  • alpine wilderness,

  • groves of Giant Sequoias, and

  • Yosemite Valley.
The 200 miles of roads give access to all of these features either by car or by free shuttle bus in some areas. To get to know the real Yosemite, however, you must leave your car and take a few steps on a trail. You don't have to walk far to discover the grandeur that can be found here and the values this special place offers. Millions of people have come to Yosemite and left refreshed and relaxed and perhaps a bit more knowledgeable about what they want out of life. See what you can find.

The story of Yosemite began about 500 million years ago when the Sierra Nevada region lay beneath an ancient sea. Thick layers of sediment lay on the sea bed, which eventually was folded and twisted and thrust above sea level. Simultaneously molten rock welled up from deep within the earth and cooled slowly beneath the layers of sediment to form granite. Erosion gradually wore away almost all the overlying rock and exposed the granite. And even as uplifts continued to form the Sierra, water and then glaciers went to work to carve the face of Yosemite. Weathering and erosion continue to shape it today.

Tuolumne Meadows and the High Country
This section of Yosemite has some of the most rugged sublime scenery in the Sierra. In summer the meadows, lakes, and exposed granite slopes teem with life. Because of the short growing season, the plants and animals take maximum advantage of the warm days to grow, reproduce, and store food for the long, cold winter ahead.

The Tioga Road (California 120), crosses this area. This scenic highway, originally built as a mining road in 1882-83, was realigned and modernized in 1961. The road passes through an area of sparkling lakes, fragile meadows, domes, and lofty peaks that only 10,000 years ago lay under glacial ice. Scenic turnouts along the road afford superb views. At Tioga Pass the road crosses the Sierra's crest at 9,945 feet, the highest automobile pass in California.

Tuolumne Meadows (at 8,600 feet) is the largest sub-alpine meadow in the Sierra. It is 55 miles from Yosemite Valley via the Tioga Road. Long a focal point of summer activity, it is also growing in popularity as a winter mountaineering area. In the summer Tuolumne Meadows is a favorite starting point for backpacking trips and day hikes. The meadows are spectacular in early summer, abounding in wildflowers and wildlife.

Rangers at the Tuolumne Meadows Visitor Center, open during the summer, can help you. Remember that Yosemite’s meadows are fragile and are easily affected by foot traffic and are closed to bicycles and autos.

A trip into the high country can be rewarding. But remember that the elevation ranges from 7,000 to 13,000 feet. Even hardy visitors find that vigorous exercise can make them short of breath. Slow your pace; take time to awaken your sense of wonder.

Glacier Point
Glacier Point is one of those rare places where the scenery is so vast that it overwhelms the viewer. Below your feet a sheer rock cliff, about 3,200 feet straight down, affords you a bird's eye view of the entire Yosemite Valley. Across the valley you can see the 2,425-foot drop of Yosemite Falls. Beyond, the panoramic expanse of the High Sierra stands out in awe-inspiring clarity. Signs identify major peaks. Sunset and full moon nights are ideal times to visit the point. A full moon transforms the pastel granite landscape into a fairyland. In summer you can drive to Glacier Point (32 miles from Yosemite Valley). In winter when the road is closed at Badger Pass Ski Area Glacier Point is a favorite destination for cross-country, skiers. But no matter how you travel or when you go, Glacier Point offers what may be Yosemite's finest view.

Giant Sequoia Groves
The Mariposa Grove, 35 miles south of Yosemite Valley, is the largest of three Sequoia groves in Yosemite. The Tuolumne and Merced Groves are near Crane Flat. Despite human pressures, these towering trees, largest of all living things, have endured for thousands of years. Only in recent years, however, have we begun to understand the Giant Sequoia environment. During the last 100 years protection has sometimes been inadequate and sometimes excessive. For example, in the late 1800s tunnels were cut through two trees in the Mariposa Grove. Conversely, good intentions created another problem, protection from fire has resulted in adverse effects.

Sequoias are wonderfully adapted to fire. The wood and bark are fire-resistant. Black scars on a number of large trees that are still prospering indicate they have survived many scorching fires. Sequoia reproduction also depends on fire. The tiny seeds require minimal soil for germination, and seedlings need sunlight. Historically, frequent natural fires opened the forest, thinned out competing plant species, and left rich mineral soil behind. But years of fire suppression have allowed debris, such as fallen branches, to accumulate, stifling reproduction and allowing shade-tolerant trees to encroach. Prescribed fires, intended to simulate natural fires and improve the health of the forest, are now set by the National Park Service.

As you look at these trees, keep in mind that they have been here since the beginning of history in the western world. The Mariposa Grove's Grizzly Giant is 2,700 years old and is thought to be the oldest of all Sequoias. Private vehicles are not permitted beyond the parking area in the Mariposa Grove. You may ride the trams through the Grove from May until October. Trails are available year-round for hiking or cross-country skiing.

This Indian word apparently meant "big tree". Wawona was once an Indian encampment and, later, was the site of a wayside hostel built in 1857 by Galen Clark. Known as Glares Station, it served as an overnight stop for visitors in transit between Yosemite Valley and Mariposa. In 1864, when Yosemite Valley and the Mariposa Grove were set aside for protection, Clark became the first guardian of the area. In 1875, the year the original Wawona road opened, the Washburn brothers purchased the area and built the Wawona Hotel that is still in operation today. Wawona focuses on Yosemite's human history. It is the setting of the Pioneer Yosemite History Center, a collection of relocated historic buildings and horse-drawn coaches.

Yosemite's wilderness is varied and offers day hiking and backpacking experiences for both the seasoned hiker and the novice. About 800 miles of trails offer a variety of climate, elevation, and spectacular scenery. Near the crest of the Sierra you can take both long and short trips at elevations above 9,000 feet. The higher regions offer a cool climate, while lower elevations are warmer and drier.

To protect Yosemite's wilderness, there are quotas for overnight use. Free wilderness permits are required and are available at ranger stations and visitor centers. Be sure to read the information you receive with your permit and observe all regulations. Above all, remember to keep your impact to a minimum. Additionally, you will need appropriate equipment and good footgear.

During winter the wilderness is receiving increased mountaineering use. Cross-country skiing and snow-shoeing have grown in popularity and open up a new world for the backpacker. The high country is a wonderland. Deep snow covers the land, and summer landmarks may be unrecognizable. But winter in the wilderness is more demanding than summer. Good equipment, warm clothing, and proper planning are essential to assure a safe and comfortable trip into the harsh Sierra winter environment. Backcountry travel both summer and winter, can be gratifying. However you are experiencing the mountains on their terms, and the mountains are not forgiving to the careless or unprepared.

Yosemite Valley
"The Incomparable Valley", it has been called, is probably the world's best known example of a glacier-carved canyon. Its leaping waterfalls, towering cliffs, rounded domes, and massive monoliths make it a preeminent natural marvel. These attributes have inspired poets, painters, photographers, and millions of visitors beginning with John Muir for more than one hundred years. Nowhere in Yosemite is the sense of scale so dramatic.

Yosemite Valley is characterized by sheer walls and a flat floor. Its evolution began when alpine glaciers lumbered through the canyon of the Merced River. The ice carved through weaker sections of granite plucking and scouring rock but leaving harder, more solid portions—such as El Capitan and Cathedral Rocks—intact and greatly enlarging the canyon that the Merced River had carved through successive uplifts of the Sierra. Finally the glacier began to melt and the terminal moraine left by the last glacial advance into the valley dammed the melting water to form ancient Lake Yosemite, which sat in the newly carved U-shaped valley. Sediment eventually filled in the lake, forming the flat valley floor you see today. This same process is now filling Mirror Lake at the base of Half Dome.

In contrast to the valley's sheer walls, the Merced Canyon along California 140 outside the park is a typical river-cut, V-shaped canyon, for the glaciers did not extend this far. Back from the rim of the valley itself, forested slopes show some glacial polish. But for the most part these areas also were not glaciated.

The valley is a mosaic of open meadows sprinkled with wildflowers and flowering shrubs, oak woodlands, and mixed-conifer forests of ponderosa pine, incense-cedar, and Douglas-fir. Wildlife from monarch butterflies to mule deer and black boars flourishes in these communities. Around the valley's perimeter, waterfalls, which reach their maximum flow in May and June, crash to the floor. Yosemite, Bridalveil, Vernal, Nevada, and Illilouette are the most prominent of these falls, some of which have little or no water from mid-August through early fall.

Take time to visit the Valley Visitor Center, where an orientation slide program and publications are available. Exhibits highlight the valley's natural and human history. Rangers are available to answer questions or assist you. The Indian Cultural Exhibit and the Indian Village, located behind the visitor center, display the cultural history of the native Miwok and Paiute people from 1850 to the present. Nearby, the Museum Gallery features artwork of past and current Yosemite artists.

Note: When you arrive in Yosemite Valley, park your car and walk to the places you want to see. Distances are short. If you prefer, use the tree shuttle bus system that serves most of the valley. Either way, you'll save gas and frustration. It you are visiting just for the day, park your car in the day-use parking lot at Curry Village.

park maps subheading

The General park map handed out at the visitor center is available on the park's map webpage.

For information about topographic maps, geologic maps, and geologic data sets, please see the geologic maps page.

photo album subheading

A general photo album for this park can be found here.

For information on other photo collections featuring National Park geology, please see the Image Sources page.

books, videos, cds subheading

Currently, we do not have a listing for a park-specific geoscience book. The park's geology may be described in regional or state geology texts.

Please visit the Geology Books and Media webpage for additional sources such as text books, theme books, CD ROMs, and technical reports.

Parks and Plates: The Geology of Our National Parks, Monuments & Seashores.
Lillie, Robert J., 2005.
W.W. Norton and Company.
ISBN 0-393-92407-6
9" x 10.75", paperback, 550 pages, full color throughout

The spectacular geology in our national parks provides the answers to many questions about the Earth. The answers can be appreciated through plate tectonics, an exciting way to understand the ongoing natural processes that sculpt our landscape. Parks and Plates is a visual and scientific voyage of discovery!

Ordering from your National Park Cooperative Associations' bookstores helps to support programs in the parks. Please visit the bookstore locator for park books and much more.

geologic research subheading

Information about the park's research program is available on the park's research webpage.

For information about permits that are required for conducting geologic research activities in National Parks, see the Permits Information page.

The NPS maintains a searchable data base of research needs that have been identified by parks.

A bibliography of geologic references is being prepared for each park through the Geologic Resources Evaluation Program (GRE). Please see the GRE website for more information and contacts.

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NPS Geology and Soils Partners

NRCS logoAssociation of American State Geologists
NRCS logoGeological Society of America
NRCS logoNatural Resource Conservation Service - Soils
USGS logo U.S. Geological Survey

teacher feature subheading

We believe that the stewardship of our national parks and public lands lies with today's students. It is imperative that we provoke in them today a sense of wonder and ownership of such places, in the hope that they will take this into the future. We hope that you will find that by using Yosemite National Park as an extension of your classroom, the science of the natural world will come alive.

General information about the park's education and intrepretive programs is available on the park's education webpage.

For resources and information on teaching geology using National Park examples, see the Students & Teachers pages.
updated on 02/11/2009  I   http://www.nature.nps.gov/geology/parks/yose/index.cfm   I  Email: Webmaster
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