Dinosaur National Monument was established on October 4, 1915, as an 80-acre monument to preserve the outstanding fossil resources at the dinosaur quarry north of Jensen, Utah. In 1938 the monument was enlarged to 203,885 acres. This proclamation vastly expanded the land base to include the river corridors and adjacent viewsheds for the major canyons of the Green and Yampa Rivers. On September 8, 1960 minor revisions to the boundary enlarged the monument to 211,141.69 acres, for the construction of entrance roads and administrative sites.
Did You Know?
Split Mountain, the name John Wesley Powell gave to one of the Dinosaur’s most recognizable features, is aptly named: over millions of years, the Green River has carved a canyon into the center of the mountain, splitting it in two.