Zion National Park is located in the Southwestern United States, near Springdale, Utah. A prominent feature of the 229-square-mile (590 km2) park is Zion Canyon, which is 15 miles (24 km) long and up to half a mile (800 m) deep, cut through the reddish and tan-colored Navajo Sandstone by the North Fork of the Virgin River. The lowest elevation is 3,666 ft (1,117 m) at Coalpits Wash and the highest elevation is 8,726 ft (2,660 m) at Horse Ranch Mountain.
Located at the junction of the Colorado Plateau, Great Basin, and Mojave Desert regions, the park's unique geography and variety of life zones allow for unusual plant and animal diversity. Numerous plant species as well as 289 species of birds, 75 mammals (including 19 species of bat), and 32 reptiles inhabit the park's four life zones: desert, riparian, woodland, and coniferous forest. Zion National Park includes mountains, canyons, buttes, mesas, monoliths, rivers, slot canyons, and natural arches.
Half Dome is nearly as whole as it ever was. The impression from the valley floor that this is a round dome which has lost its northwest half is an illusion. From Glacier Point or from Washburn Point, Half Dome can be seen as a thin ridge of rock oriented northeast-southwest, with its southeast side almost as steep as its northwest side except for the very top. Although the trend of this ridge, as well as that of Tenaya Canyon, is probably controlled by master joints, 80 percent of the northwest "half" of the original dome may well still be there.
On March 28, 2009, a large rock slide of 1,500,000 cubic feet (42,000 m3) occurred from Ahwiyah Point. The slide happened at 5:26 a.m and damaged a large area under the dome. No one was injured but hundreds of trees were knocked down and a portion of the Mirror Lake trail was buried. The slide registered on seismographs as a 2.5 earthquake