April 22, 2004
The above photo, taken last month, shows a classic view of beautiful Yosemite National Park, located in the Sierra Nevada Range of east central California. Yosemite Valley is a profound example of a glacially modified valley. The presence or absence of jointing in the Sierra Nevada batholith (see glossary below) determined the effectiveness of the erosive and sculpting powers of glaciers, which have long since retreated. Most of Yosemite is comprised of plutonic igneous rocks -- rocks that form deep underground when molten rock cools and solidifies. Bridalveil Falls, at center, is framed by towering montane forests and Yosemite's massive granite landforms.