Terminal moraine then blocked the river's course and the valley was turned into a lake. It gradually silted up, creating a rich, fertile meadow, now bordered by black oak and covered in wild flowers.Although in summer Yosemite Valley is teeming with visitors and traffic jams, you can leave the crowds behind quite easily More than 94 per cent of Yosemite is designated wilderness. The high alpine Tuolumne Meadows, in the east, almost on a level with the tops of the mountains, give access to trails in Yosemite's wild back country. With panoramic views towards the saw-toothed Cathedral Range, this was one of John Muir's favourite spots. In the north there are numerous glaciated canyons while in the thickly forested south, near Wawona, you have another spectacle, the giant sequoias of Mariposa Grove.The sequoia, or sierra redwood, is the biggest living thing on earth (some weighing up to one thousand tons).

In Mariposa Grove there are five hundred sequoias, some 3,000 years old. The Grizzly Giant is the largest tree in the grove and fifth largest in the world. The Batchelor and Three Graces stand near the path, while the Fallen Giant's claim to fame stems from a photo taken in 1899 of cavalry officers and their horses standing on top of the fallen tree Well, not the white man. Their history only dates back a hundred and fifty years or so. However, we're only talking thousands rather than millions of years now. The Ahwahneechee (a subtribe of the southern Miwok people) lived in Yosemite Valley with its sparkling waterfalls and pine forests, undisturbed for about three thousand years.

Gradually, however, the white man pushed further into California's unexplored interior.First to approach from Wyoming in the west were fur trappers. It's thought they penetrated as far as Tuolumne Grove, as records show that they came across giant sequoias. It was gold, though, that signalled the end of Yosemite's isolation. The gold rush began in 1848, and by the early 1850s prospectors were inching into the Sierra Nevada foothills.

The gateway towns of Mariposa and Groveland became important settlements. In 1851 the first skirmishes took place between the new settlers and the native tribes. The Mariposa Battalion was dispatched to deal with natives who had raided some of the outposts. Pitching camp in the valley they named it Yosemite, mistakenly thinking that this was the native name. (Yosemite actually means "some of them are killers".) A second expedition captured the chief, Tenaya.