eternal sunrise, eternal sunset, eternal dawn and gloaming. on sea and continents and islands, each in its turn, as the round earth rolls. john muir. captioning made possible by friends of nci captioned by the national captioning institute --www.ncicap.org-- announcer: to further explore "the national parks: america's best idea," visit pbs online at... "the national parks: america's best idea," a film by ken burns is available on dvd and blu-ray. a companion book and cd are also available. to order, visit shoppbs.org or call 1-800-play-pbs. for a century, americans have had the opportunity to enjoy our most beautiful natural treasures through the remarkable efforts of our national park service. we're proud to support ken burns and share his belief that by preserving america's past we can build a stronger future. the films of ken burns have captured the beauty, the texture, and the emotion of american history. general motors is proud to support this great artist his outstanding work on pbs, and the great story that is america. our national park