An artist s palette of color stretches across the Geneva Creek iron fens. (Courtesy photo)
If you go
Highlights: Unique iron fens, golden aspen, spectacular views
Distance: About 1.2 miles to the first fen
Elevation: 10,700 to 11,300 feet
Access: From Georgetown, drive over Guanella Pass, where the aspen usually peak by mid-September. Turn west on Geneva Creek Road (FS 119). Continue for about 4 miles beyond the campground to the barricade and park alongside the road.
Cascading streams flow over massive terraces banded in maroons, blood-reds, orange-golds and lemon-yellows laced with tendrils of emerald green algae. In some places, iridescent turquoise, sapphire and amethyst colors sparkle on a black pebbly matrix. Had we not looked up to the red ridges above, we might have imagined we were in Yellowstone.
Instead, this geologic wonder, known as the Geneva Creek iron fens, is located just on the other side of Guanella Pass and is registered as a Colorado State Natural Area. Iron fens are not known to exist anywhere in the world except in Colorado, where eight have been documented.
These wetlands differ from northern bogs in that they are fed by ground water arising from surrounding calcareous rocks. The Clear Creek County website describes the formation of this phenomenon that "begins with a series of springs flowing over highly fractured, highly mineralized bedrock rich in pyrites producing extremely acidic (pH3), mineral-rich water." The iron-saturated peat called "limonite" forms ledges and terraces that, in the upper reaches of Geneva Basin, stretch as wide as a football field.
Getting to the fens is not easy and involves driving a 4-mile stretch of Geneva Creek Road that took us 50 minutes. Don’t try it without four-wheel drive and high clearance.
The trail begins at the point where the road forks and a barricade closes the left-hand branch to vehicles. It’s important to protect this fragile environment that supports such rare plants as Girgensohn sphagnum moss. Park alongside the road and walk in past the barricade.
Mineral-rich water forms abstract paintings in the fens. (
Continue up the old road that soon breaks out into a meadow. Rust-colored Geneva Creek flows to the left and mountains streaked with red rise above. In September, aspens turn golden while blue gentians and yellow and lavender asters continue to bloom.
In about half a mile, you come to a shallow pond across the road. Either wade or rock hop across the pond. Once we bushwhacked around it and became grievously entangled.
Beyond the pond, the trail climbs fairly steeply to an unsigned fork. Take the right branch to climb another 0.2 miles to the main fens and prepare to spend an hour or so in rapt contemplation.
It’s worth returning to the fork and taking the other branch up to some additional fens. Luxuriant grasses and alder bushes surround the fens and turn russet in September, and wintergreen berries turn red and sweet.
It’s possible to hike to the fens from a point on the Geneva City Road that forks right at the barricade. We drove about a mile up to the signs for the fens and decided against that route. It’s steeper, and we were anxious to get off the shelf road before other vehicles arrived. If you decide to brave this stretch of road, you can also visit the ruins of the Geneva City cabins and mines in the basin above the fens.
Dispersed campsites — many in the aspen — are scattered along Geneva Creek Road. Steller’s jays, gray jays and chipmunks forage around the campsites, and you may be engulfed — as we were — in a wave of migrating fall warblers.
Ruth Carol and Glenn Cushman are the authors of "Boulder Hiking Trails," published by Graphic Arts Books