Vacation brochures tout the Grand Mesa as the world’s largest flat-topped mountain. Scientists would rather play it safe on that claim. But it’s fair to say the Grand Mesa counts among the biggest around, with more than 50 square miles of pine and aspen forests, trout streams and some 300 lakes.
Most curious is how the massive mountain, which rises abruptly several thousand feet from many miles of the surrounding sagebrush-covered flatland, got where it is. The Grand Mesa reaches an elevation of some 10,000 feet.
The Grand Mesa is an erosional remnant, explains Pete Varney, a geology professor at Denver’s Metropolitan State College. Eight million to 10 million years ago, lava flows covered a region of sedimentary rock. Streams – likely Plateau Creek and the Gunnison River and their offshoots – flowed through the area and gradually cut away at the softer sedimentary rock; the rock capped by basalt, a much harder volcanic rock, stayed put.
With time, that erosion produced the mesa’s cliff walls and the canyons of the river valleys.
Varney suspects “subsequent uplifts (of the Earth’s surface) gave the streams a lot of energy to flow and cut away the sedimentary rock.”
If you look at a map of the area, you’ll see the Grand Mesa’s borders roughly match the course of Plateau Creek, near Plateau City and Collbran to the north and the Gunnison River, near Delta, to the south.
Get there: Grand Mesa dominates western Colorado’s landscape, but it’s not the only mesa in town. To make sure you’re not wandering around Colorado National Monument, or Fruitland Mesa, take Interstate 70 to Colorado 65, in De Beque Canyon, about 6 miles east of Palisade. Head east on Colorado 65 to the top of the mesa. Denver photographer John Fielder recommends taking a side journey along Forest Road 105 to Lands End for a stunning view of the Uncompahgre Plateau and the Gunnison River.
– Kelly Pate Dwyer, Special to The Denver Post
