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. 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.

Yosemite Valley

"The Incomparable Valley," so it has been called probably the world's best known example at 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, John Muir, and millions of visitors for more than 100 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 intact harder portions, such as El Capitan and Cathedral Rocks. The glacier greatly enlarged the canyon that the Merced River had carved though 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 State Route 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 forested slopes show some glacial polish, but, for the most pan, these areas were not glaciated.

The valley 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 bears flourishes in these communities. Waterfalls around the valley's perimeter reach their maximum flow in May and June, and crash to the floor. Yosemite, Bridalveil, Vernal, Nevada, and Illiouette are the most prominent falls, some of which have little or no water from mid-August through early fall.

Notes to the Visitor:

Take time to visit the Valley Visitor Center, where a new film, Spirit of Yosemite, and publications are available. Exhibits highlight the valley's natural and human history. Rangers are available to answer questions or assist you. Behind the visitor center, a self-guiding walk leads through the Indian Village. Nearby, the Indian Cultural Museum displays the cultural history of the native Miwok and Paiute people from 1850 to the present, and the Museum Gallery features artwork of past and current Yosemite artists.

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 free shuttle bus system that serves most of the valley. Either way, you'll save gas and frustration. If you are visiting for the day, park your car in the day-use parking lot at Curry Village.

Meadows, riverbanks, and oak woodlands have been severely damaged by long-term human uses. Please respect restoration efforts in these areas and stay on maintained trails.

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 winter ahead.

The Tioga Road, State Route 120, crosses this area. This scenic highway, originally built as a mining road In 1882-83, was realigned and modernized in 1981. 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. Overlooks along the road afford superb views. Al Tioga Pass the road crosses the Sierra's crest at 9,945 feet, the highest automobile pass in California.

Tuolumne Meadows, at 8,800 feet, Is the largest subalpine meadow in the Sierra. It is 55 miles from Yosemite Valley via the Tioga Road. Long a focal point of summer activity, it is 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.

Notes to the Visitor:

A trip into the high country can be rewarding. But remember that the elevation ranges from 7,000 to 13,000 feet, and the vigorous exercise can make even hardy visitors short of breath. Slow your pace, and 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, 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 Fiat Despite human pressures. These towering trees, largest of all living things, have endured for thousands of years. Only in recent years, 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 mineral soil for germination, and seedlings noon 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, stilling 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.

Notes to the Visitor:

As you look at these trees, keep In mind that they have been here since the beginning of history in the western world. Giant sequoias can live to be 3,000 years old. Private vehicles are not permitted beyond the parking arm In the Mariposa Grove. You my ride the trams through the Grove from May until October. Trails are available year-round for hiking or cross-country skiing.

Wawona

Wawona was once an Indian encampment and, later, was the site of a wayside hotel built in 1857 by Galen Clark. Known as Clark's Station, it served a stop for visitors in transit between Yosemite Valley and Mariposa. In 1884, 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.

Wilderness

Yosemite's wilderness is varied and offers hiking and backpacking experiences for 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 Nevada you can take long and short trips at elevations above 9,000 feet. The higher regions offer a cool climate; lower elevations are warmer and drier.

Notes to the Visitor:

To protect Yosemite's wilderness, free wilderness permits are required for overnight use. They are available at front country ranger stations and visitor centers. Maps and guide books are available at visitor centers to help you plan your trip. Be sure to read the Information you receive with your permit and observe all regulations. Remember to keep your impact to a minimum. Please use appropriate equipment and good footgear. If your trip plans include a visit to Yosemite's wilderness areas, please check the Wilderness Guide.

In winter the wilderness is receiving increased mountaineering use. Cross-country skiing and snowshoeing have grown In popularity and open a new world for the wilderness user. The high country is a wonderland. Deep snow covers the land, and summer landmarks may be unrecognizable. Winter In the wilderness is more demanding than summer. Good equipment, warm clothing, and proper planning are essential for a safe and comfortable trip into the harsh Sierra Nevada 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.

When you get your wilderness permit, winter or summer, ask about trail conditions, weather forecasts, campfire regulations, and special precautions you should take in the area where you will be traveling. Double check your equipment and food, stay on established trails, don't shortcut switchbacks, and observe proper food storage regulations. If you hike alone, tell someone where you're going and when you will return. For stock use, check at any ranger station. Pets and bicycles are not allowed in the wilderness.