In 1864, President Abraham Lincoln signed the Yosemite Grant to protect the wild lands of Yosemite Valley and Mariposa Grove. Yosemite became a federally designated national park in 1890 with the National Park Act. Yosemite’s iconic polished granite domes, walls, and valleys—the result of glaciation—are the basis for the park’s preservation. John Muir and Ansel Adams are credited for conservation efforts through their respective writing and photography. Yosemite has an elevation range of approximately 3,000 to 13,000 feet, and is home to diverse ecosystems and microclimates. The expansive forest is home to hundreds of animal species, including the endangered Sierra Nevada bighorn sheep.