In contrast to the big walls of Yosemite Valley, rock climbing at Tuolumne generally consists of short to medium length routes on eleven major domes and a number of minor ones. Since the area is all at a high elevation, the climbing season is mainly over the summer months (June to September). The rock is porphyritic granite, a very strong form of granite and the local ethic is to limit the placement of bolts on new routes and to forbid the addition of bolts to existing routes.br/br/Yosemite National Park reaches across the western slopes of the Sierra Nevada mountain chain in central California. It is internationally recognized for its spectacular granite cliffs, waterfalls, clear streams and Giant Sequoia groves. 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, with almost 95% of the park being designated wilderness.