Boulder Field via the Longs Peak Trail, Rocky Mountain National Park, Colorado

Hiking to the Boulder Field via the Longs Peak Trail is a challenging 12.3 mile out and back trail with a 3,360 feet elevation gain near Allenspark, Colorado. The trail offers great views of the east and north faces of Longs Peak, alpine tundra, the Boulder Field, the Agnes Vaille shelter hut and views into Glacier Gorge.

Overview

Hiking to the Boulder Field via the Longs Peak Trail in Rocky Mountain National Park offers adventurers a profound experience of Colorado’s high-altitude wilderness. This trail, spanning 12.3 miles round trip, begins near Allenspark and involves a significant elevation gain of 3,360 feet, making it a demanding yet incredibly rewarding journey for seasoned hikers.

Starting from the Longs Peak Trailhead, the path winds through dense forests and gradually transitions into a more exposed alpine terrain. Hikers are treated to breathtaking vistas of Longs Peak’s formidable east and north faces. The trail’s journey through the alpine tundra is particularly notable, where the thin air, cooler temperatures, and unique flora provide a stark contrast to lower elevations.

Upon reaching the Boulder Field, hikers are greeted by an otherworldly landscape of massive rocks, a testament to the geological forces that have shaped this region over millennia. Here, the Agnes Vaille shelter hut stands as a historical landmark and a resting point, named after the woman who perished during a blizzard on the mountain in 1925.

This hike, while not reaching the summit of Longs Peak, still offers ample rewards. From the Boulder Field, one can appreciate views into the dramatic Glacier Gorge, and the surroundings provide a vantage point to several other notable features like Peacock Pool and Chasm Lake. For those with a penchant for exploration without the technical climbing, the Keyhole route or the ridge to Chasm View between Mount Lady Washington and Longs Peak offer additional scenic detours.

Longs Peak itself, standing at 14,259 feet, is not only the highest peak in Boulder County and Rocky Mountain National Park but also serves as a beacon for those who seek to understand the raw beauty and challenge of Colorado’s mountains. Named after explorer Stephen Harriman Long, this peak embodies the spirit of adventure that draws people to the Rockies. Whether one’s goal is personal challenge, nature’s beauty, or historical appreciation, the hike to the Boulder Field encapsulates all these elements, providing a rich outdoor experience.

Looking southwest across the Boulder Field towards Longs Peak. The famous Keyhole is seen on the right side of the photograph at the top of the ridge.

Getting to the Trailhead

Getting to the Longs Peak Trailhead in Rocky Mountain National Park requires some preparation, but it’s accessible for those willing to plan ahead. Here’s how:

From Denver or Boulder: Drive: Head west on US-36 towards Boulder. Once past Boulder, continue on CO-119 towards Nederland. From there, take CO-72 west which turns into CO-7 north at Allenspark. Follow CO-7 through Allenspark until you reach the park entrance. From Denver, it’s roughly a 1.5 to 2-hour drive. From Boulder, expect about an hour.

Park Entrance: You’ll need a timed entry permit for the Longs Peak area from late May to mid-October. These can be reserved in advance through the National Park Service’s reservation system.
Pay the park entrance fee or show your National Parks pass.

Trailhead Access: After passing through the entrance, continue on Longs Peak Road (Highway 7) for about 10 miles to the trailhead parking area. Arrive early as the parking lot fills up quickly. If full, there’s overflow parking near Wild Basin, but this adds a shuttle or significant walk to your journey.

Shuttle Services: During peak season, consider using shuttle services from Estes Park or other nearby towns to avoid parking issues. Shuttles might require reservations.

Remember to check for road conditions, especially after heavy snow or during early spring when trails might still be closed or hazardous.

Geography and Geology

The Boulder Field on Longs Peak in Colorado’s Rocky Mountain National Park is an awe-inspiring geological feature, emblematic of the mountain’s rugged character. This area lies at an elevation of about 12,760 feet, just below the Keyhole Route’s crux, offering a dramatic landscape shaped by millennia of geological processes.

Formation:

The Boulder Field primarily consists of large granite boulders, remnants of extensive erosion and weathering. The parent rock for these boulders is Precambrian-aged Silver Plume Granite, which was intruded over a billion years ago. Over time, exposure to the elements like freeze-thaw cycles, wind, and occasional glaciers has fragmented this granite. The process of frost wedging is particularly evident here, where water seeps into cracks, freezes, expands, and eventually splits the rock apart.

Geographical Features:

Elevation: The field sits at a high altitude, contributing to its harsh, alpine climate. The thin air, cooler temperatures, and intense UV radiation create a unique microclimate.

Vegetation: At this altitude, vegetation is sparse, dominated by alpine tundra species like mosses, lichens, and tough grasses that can withstand the severe conditions.

Boulder Layout: The boulders are not uniformly distributed but are scattered in a chaotic array, some forming natural shelters or cairns. This layout is a result of gravitational sorting where smaller rocks fill the spaces between larger ones, creating a somewhat stable but unpredictable terrain.

Geological Significance:

Glacial Activity: Though not currently under ice, signs of past glaciation are evident. The Boulder Field likely saw multiple glacial advances and retreats, which helped shape its current form by carrying and depositing rocks as glaciers melted.

Tectonic Influence: The uplift of the Rockies, including Longs Peak, is due to tectonic forces, particularly the Laramide orogeny. This orogenic event pushed what was once seabed upwards, exposing granite to the forces of weathering.

This geological spectacle at Boulder Field not only showcases the dynamic history of Earth’s crust but also provides a natural barrier that hikers must navigate, adding to the adventure of reaching Longs Peak’s summit or simply exploring this high-altitude wonder.

Journal

I started my hike just before 6 AM and on my downhill phase of the hike, an afternoon thunderstorm was blowing into the region. I suggest starting earlier at 4 AM and planning on being off the mountain between noon and 2 PM. Hikers at the higher elevations in the Rockies, including Longs Peak should be especially conscious about the dangers of lightning. According to the National Outdoor Leadership School, lightning density maps show lightning strikes occurring more often at higher elevations in the Rocky Mountains where the air and climate is drier. On average, eleven people die from lightning each year in Colorado.

Looking southwest across the Boulder Field towards Longs Peak. The famous Keyhole is seen on the right side of the photograph at the top of the ridge.

View looking east from the Goblins Forest on the Longs Peak Trail. Getting an early 4 AM start allows adventurers to (1) see the best parts of the trail in the morning light, (2) return to the trailhead before the afternoon thunderstorms arrive, (3) find a parking spot at the trailhead somewhere west of the Mississippi River. The parking lot fills up fast!

Starting hiking in the early morning darkness, the East Longs Peak Trail starts the climb though the Goblins Forest. This forest has uniform lodgepole pine trees.

Looking east over the Goblins Forest at sunrise from the Longs Peak Trail.

Hike 0.5 miles to a signed trail junction and stay left on the main trail. Continue up through the forest and pass Goblins Forest. Switchback up a hill before crossing Alpine Brook on a log bridge. Since I started at 6 AM, the sun is starting to rise over the hills by the time I get up to the noisy Alpine Brook and Larkspur Creek. Towards the top of the Goblins Forest, there are subalpine fir, limber pine, and Engelmann spruce trees.

The Longs Peak trail rises above the tree line to an open treeless tundra.

As the trail reaches the tree line, the vegetation turns to crooked, bent and twisted krummholz trees. These trees are a type of stunted, deformed vegetation encountered in the subalpine tree line landscapes. Above the subalpine krummholz landscape lies numerous conifer species in an open treeless tundra.

The trail continues to climb towards the Boulder Field.

Leave the heavy forest shortly after the stream crossing and continue up to tree line near 11,000′ (approximately 2.5 miles from the trailhead). Longs Peak is now in view as well as the route past Mt. Lady Washington and to Granite Pass.

Reaching Granite Pass is a significant milestone on the way up the Longs Peak Trail to the Boulder Field.

The traverse is a moderately long 4.2 miles with an elevation gain of 2,680 feet to Granite Pass (Elevation 12,080 feet). From Granite Pass, the view to the north begins to reveal Rocky Mountain National Park. Continue along the switchbacks up to the North Boulder Field. Longs Peak will now be in view as you ascend the mountain.

The North Longs Peak Trail heads off to the right. Stay left on the East Longs Peak Trail and switchback up and easy slope to reach the north end of the Boulder Field, near 12,400′. The north and east faces of Longs come into view, as well as Storm Peak (13,326′) ahead. Follow the trail south into the Boulder Field and past some established tent sites in the middle of the field. There is a restroom in this area.

View looking north from the Boulder Field towards Glacier Gorge.

I would rate this hike as difficult with an estimated hiking time of 6 to 8 hours.  See my nearby Strava.com file from my hike on August 23, 2017, which took me just under 7 hours (moving time) with my elapsed time taking about 8 hours. I did this hike with a sore meniscus on my left knee and an injured left quad muscle that kept me out of both the 2017 London and New York City marathons. I didn’t start running again until February 2018. Later that fall I finished the New York City Marathon. I was determined to hike up to the Boulder Field nonetheless, despite my knee challenged status. Most of the other hikers on the mountain that day quickly passed me. Trekking poles are a must on the downhill phase even if you don’t have a sore meniscus.

If your next goal is to reach the Keyhole, which is a notch in the rugged ridge between Longs Peak and Storm Peak. The trail finally runs out near 12,800′ on the south end of the Boulder Field but follow cairns up through the rocks to reach the Keyhole. The Keyhole Route to the top of Longs Peak is an Alpine Climbing NCCS Rating of Class III approach that is better suited for more adventurous and experienced hikers.

Camping is available at the Boulder Field and also on the lower portions of the mountain, such as Goblin’s Forest next to the stream at the bottom. It is also possible to camp to the south of the mountain at Sand Beach Lake. Camping is first-come, first-served, limited to 3 consecutive days, and is tents only.

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