Fowler Trail - 4.0 Miles Round-Trip

The Fowler Trail winds through open space at the mouth of Eldorado Canyon and ends at the Rattlesnake Gulch Trailhead within Eldorado Canyon State Park. The final .7 miles feature 12 points of biological and geological interest explained by free brochures available at the Eldorado Canyon Visitor Center. This short, mild trail runs mostly over groomed service roads, ideal terrain for young families, runners and cross-country skiers. Connections with the Spring Brook Trail North, Goshawk Ridge Trail and Rattlesnake Gulch Trail provide additional routing options for longer treks through Open Space lands and the Eldorado Canyon interior.

The Fowler Trail begins on a wide service road, rising gently and winding deliberately along spacious contours of the outer-canyon. The steady climb soon yields picturesque views across the canyon mouth and northern foothills. You'll pass the Spring Brook North Trail split (.55 miles : 6,075') and continue through a blasted notch in the road (.75 miles) to the Goshawk Ridge Trail split (1.05 miles : 6,105'). Here the Fowler Trail levels considerably through the Eldorado Canyon State Park boundary (1.3 miles : 6,110') and narrows on rocky single track. It bends west and enters the canyon along the south wall. The trail glides easily above a short piece of South Boulder Creek to its terminus at the Rattlesnake Gulch Trailhead (2.0 miles : 6,087').

The striking walls above reveal the canyon's 1.7 billion year history in a very short space. Exposed granite at the canyon's west end was formed by seeping magma that cooled and solidified quartz, feldspar and biotite into igneous rock. Over this granite is 1.6 billion year old quartzite, which began as a thick layer of eroded sand that was buried, compressed into sedimentary rock and pushed closer to the earth's core. Rising heat and pressure transformed this layer into metamorphic rock.

300 million years ago the Ancestral Rocky Mountain uplift bore mountains of granite that slowly eroded, depositing thick layers of sand and pebbles downstream. These sediments were compressed into a layer of sandstone known as the Fountain Formation, famously exposed in Boulder's Flatirons and Golden's Red Rocks Amphitheater. Hematite, or iron ore, gives these rocks a distinguished red hue. Most of Eldorado Canyon's highest cliff walls are part of this formation.

280 million years ago sand blew west from eastern deserts, settling as dunes over the Fountain Formation and compressed into sedimentary rock over the next 40 million years. This newest layer, known as the Lyons Formation, is visible at the mouth of Eldorado Canyon. 65 million years ago a second Rocky Mountain uplift forced horizontal layers of the Fountain and Lyons formations upward, exposed today by the erosive force of South Boulder Creek. These tilted layers usher water 8,000' underground, where it's forced back to the surface as an artesian spring in the historical town of Eldorado Springs.