Complex sentence: William J. Whalen was the 10th director of the National Parks Service joined the United States National Park Service in 1965 as a Job Corps counselor and advanced to posts in National Capital Parks and Yosemite before becoming superintendent of Golden Gate National Recreation Area in 1972.
Split into simpler sentences: William J. Whalen was the 10th director of the National Parks Service. He joined the United States National Park Service in 1965 as a Job Corps counselor and advanced to posts in National Capital Parks and Yosemite before becoming superintendent of Golden Gate National Recreation Area in 1972.