Royal Arch (6,915') is perched high along a rugged fold in the Boulder Flatirons. These rocks are remnants of the Fountain Formation, a mineral-rich sand eroded from the ancestral Rocky Mountain uplift 300 M years ago. Sediments deposited by the ebb and flow of inland oceans compressed this layer into sandstone, thrust upward 45 M years ago by the same tectonic forces that created our modern Rocky Mountains. Royal Arch is a fragment of the exposed Fountain Formation sculpted by water, wind and mechanical erosion into the 20’ span we see today.

The trail follows Blue Bell Road along open space into ponderosa woodlands at the base of the Flatirons

Royal Arch was sculpted from a stray fracture in tilted rock layers of the Fountain Formation

Ponderosa bark turns from dark brown-black to a distinct cinnamon-red color at about 90 years of age

Substantial metallic ore deposits formed in Colorado during the early-mid Tertiary Period

Inland seas advanced and retreated several times during the late Cretaceous Period

Views west stretch across the Western Mountain Parks Habitat Conservation Area to the Continental Divide

Royal Arch (6,915')

Striations in the rock are clear and easy to examine from high points along the trail

Steep cliffs along the Flatirons, Green Mountain, Bear Peak and S. Boulder Peak provide critical nesting habitat for Golden Eagles and Peregrine Falcons

The Bluebell Shelter on the way to Royal Arch.