Although this 325sq mi parkland extends into Utah, its headquarters and visitor center are 2mi east of tiny Dinosaur, Colorado. A scenic drive to Harpers Corner climaxes with a 1.5mi hike to a viewpoint over the confluence of the Yampa and Green Rivers at Echo Park. Side roads to other overlooks are fit for four-wheel-drive vehicles only. To see dinosaur skeletons, visitors must travel west 20mi on US-40 to Jensen, Utah, then north 7mi on Rte. 149 to the Dinosaur Quarry. About 150 million years ago, such creatures as the herbivorous apatosaurus and stegosaurus, and the carnivorous allosaurus, lived and died here. The Quarry was once a sandbar where carcasses accumulated, covered with sediment and preserved.