Images of the numbered Flatirons on Green Mountain are ubiquitous symbols of the city of Boulder. Of note is the East Face Standard route on the Third Flatiron guidebook author and longtime climber Richard Rossiter calls it 'The best 5.4 in the solar system.' A symbol of Boulder View of the first through fifth Flatirons (right to left, north to south)įrom Chautauqua Park on a winter morning. They are popular destinations for hikers and rock climbers, with rock grades ranging from easy (5.0) to world-class (5.14b). The Flatirons on Green Mountain and Bear Peak are within the City of Boulder Open Space and Mountain Parks system. Other manifestations of the Fountain Formation can be found in many places along the Colorado Front Range, including Garden of the Gods near Colorado Springs, Roxborough State Park in Douglas County, and Red Rocks Amphitheatre near Morrison. The Flatirons were subsequently exposed by erosion. Geologists estimate the age of these rocks as 290 to 296 million years they were lifted and tilted into their present orientation between 35 and 80 million years ago, during the Laramide Orogeny. The Flatirons consist of conglomeratic sandstone of the Fountain Formation. There are two hypotheses regarding the origin of the current name, one based on resemblance to old-fashioned clothes irons, the other based on resemblance to the Flatiron Building completed in 1902. The Flatirons were known as the 'Chautauqua Slabs' c. Numerous additional named Flatirons are on the southern part of Green Mountain, Bear Peak, and among the surrounding foothills.

8,148 ft or 2,484 m), and the term 'The Flatirons' sometimes refers to these five alone.

There are five large, numbered Flatirons ranging from north to south (First through Fifth, respectively) along the east slope of Green Mountain (elev. The Flatirons are rock formations in the western United States, near Boulder, Colorado, consisting of flatirons.

Flat irons boulder