Galen Clark (1814-1910) is known for his discovery of the Mariposa Grove of Giant Sequoia trees and for his role as Guardian of Yosemite National Park for 21 years. Upon his discovery of the Mariposa Grove of Giant Sequoias, he spent the majority of his time exploring the area and teaching others about the mysteries of the giant, cinnamon-colored trees. This passion led to him writing letters to friends and congress, eventually leading to the passing of the Yosemite Grant. This grant was the first of its kind, stating that it would protect Yosemite Valley and the Mariposa Grove of Giant Sequoias for, "public use, resort, and recreation... to be left inalienable for all time... " Galen then became the first "guardian of the grant". Toward the end of his life he was desperately poor. His works include: Indians of the Yosemite Valley and Vicinity (1904), The Big Trees of California (1907) and The Yosemite Valley (1910).