In 1853, after being told by doctors that he had just six months to live, Galen Clark moved to Yosemite National Park. There, he defied medical expectations and lived for another 57 years. During this time, he discovered the Mariposa Grove of Giant Sequoia trees and dedicated himself to exploring the park and teaching others about the massive trees. His passion for the area earned him his reputation as guardian of the park and led to the passing of the Yosemite Grant, which ensures what? Discuss