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Burnt Fork - Peter Sinks, 14 September, 2025

On Sunday September 14, 2025, beginning the last full week of summer, thirteen Cache Hikers embarked on a rewarding point-to-point hike in the upper reaches of Logan Canyon, starting from the South Sinks area and ascending via the Burnt Fork Trail to Peter Sinks, before descending via the scenic Stump Hollow Trail.  This route, nestled in the Bear River Range within the Wasatch-Cache National Forest, offered a moderate challenge with about 1,100 feet of ascent and 1800 feet of descent over roughly 9 miles.  The weather was mild with clear to partly cloudy skies—typical mid-September conditions with highs in the 60s°F and a gentle breeze—making it an ideal day for exploring this high-elevation terrain around 8,000-8,500 feet. The trail system showcases nearly every habitat in the range, from open meadows to dense forests, and provides stunning panoramic views of the canyon's dramatic limestone formations.

We began just after 9:00 a.m. from South Sink on the Sinks Road, located south of Bear Lake Summit, just east of Peter Sinks. South Sink is one of several karst depressions in the area—natural bowl-like sinkholes formed by groundwater eroding the underlying limestone and dolomite rocks. It is similar to but smaller than its famous neighbor, Peter Sinks.  The Burnt Fork Trail, popular with mountain bikers, starts as a faint, old jeep road that follows a single-track trail across the sink for about half a mile and then winds northwest up a narrow side canyon for another 1.5 miles, gradually steepening as it climbs.  We could find no explicit historical documentation that explains the exact origin of the name "Burnt Fork." However, based on patterns in Utah's geographical naming conventions and the regional context, the name likely derives from a historical wildfire or controlled burn that scorched the area along the fork of a creek or drainage in the canyon.  It's a moderately challenging ascent, with a steady six hundred feet of gain, but the grade is a consistent uphill that rewards you with breaks in the shade.  Vegetation here is diverse and reflective of the subalpine zone: the lower sections feature an open sagebrush meadow. As you ascend into the canyon's more sheltered areas, the landscape shifts to a mixed conifer forest and aspens, with understory shrubs providing bursts of fall color in shades of yellow and red.  Views along Burnt Fork are intimate at first, framed by the canyon walls with glimpses of the surrounding ridges, but they open dramatically toward the top. Along the way we saw a small group of deer to the north of the trail.  The air felt fresh and invigorating, and the trail's northwest angle provided filtered sunlight that made the hike feel serene rather than strenuous. We reached the junction with Peter Sinks after about 60 minutes, feeling the elevation but energized by the changing scenery.

Arriving at Peter Sinks felt like stepping into a geological time capsule. This iconic site is a pair of large, bowl-shaped sinkholes at around 8,100 feet elevation, formed over millennia by karst erosion in the limestone bedrock of the Bear River Mountains. It's famously known as one of the coldest spots in the contiguous United States, thanks to its topography: the depressions trap dense, cold air overnight like a natural freezer, preventing it from draining away. On February 1, 1985, a record-low temperature of -69.3°F was recorded here—the lowest ever in Utah and second-lowest in the lower 48 states (just behind Rogers Pass, Montana). The site now hosts two automated weather stations from the Utah Climate Center to monitor these extremes. Even in summer, lows can dip well below freezing.  This morning the temperature at the bottom of the sink had dipped to 21.8°F.  No trees grow on the basin floor due to the harsh microclimate.  Today it is a grassy, open meadow with sparse vegetation, surrounded by higher ridges that block sunlight and wind. 

Rather than our typical hike to the bottom of the sink, we decided to visit the weather station located on the rim of Peter Sinks.  We picked up the trail and headed northeast along the rim.  After about a half mile, we went off-trail to the east a short distance to get an outstanding overlook view of Bear Lake to the east.  After a short pause for the views, we followed the unmaintained northwest trail, then went off-trail to reach the rim weather station.   The temperature at the rim at that time was about 56°F matching the temperature at the bottom of the Sinks at that time.  After a brief stop admiring the views, we decided to split into two groups.  Four decided to descend to the bottom of the sinks, while the others decided to go back to the trail and continue until it reached the Stump Hollow Trail where they would wait for the other four to rejoin the group. 

The group of four descended the slope of the sink on a slightly rocky surface and skirted the thick sagebrush near the bottom of the sinks, and spent about 30 minutes exploring, wandering the flat basin and peering into the depressions.  One hiker descended into one of the depressions and measured the temperature at the bottom.  At the bottom, the temperature this day was about 40°F.   It was surprisingly calm and silent, with a subtle chill in the air even on this mild late morning, a reminder of its winter ferocity.  Peter Sinks isn't just a cold spot; it's a unique alpine basin that highlights the Bear River Range's karst features, with nearby siblings like Middle Sink, North Sink, and South Sink dotting the landscape along US-89.  The small group then returned to the Stump Hollow trail and hiked a short distance to meet the other group.  We ate lunch in a shady spot with downed trees available to sit on.  After a short break for lunch, we continued down the Stump Hollow Trail.

For the return, we followed the Stump Hollow Trail, dropping north back toward the highway. This 4.5-mile descent is the highlight for many, rated moderate overall but with a nice downhill flow that's popular for mountain biking too. The trail starts rocky and steep from the junction before smoothing out. It then weaves through a deep pine and fir forest and aspen groves, switch-backing down with about 1,600 feet of loss over consistent grades. The upper section is rough, but it transitions to a smooth, fast singletrack in the lower third, complete with built-in berms and small jumps.  The condition of sections of the trail was evidence that it gets a lot of mountain bikers use.  Vegetation on Stump Hollow mirrors the ascent but with more emphasis on the forested understory: thick stands of aspen and maple add some early fall golden hues, interspersed with meadows of wild grasses and a few late-season wildflowers. When we stopped for a short rest, we discussed taking another detour to catch a view of Horse Lake but decided against it.  Views are the star here—frequent openings reveal Logan Canyon below, with sweeping panoramas of the river valley and peaks of the Bear River Range.  Easily observable were Beirdneau, Jardine, Elmer, Naomi, Gog, Magog, and Doubletop peaks.  There is a great distant view of the white cliffs above White Pine Lake surrounded by Mount Gog and Mount Magog.  As we neared the bottom we took a left on the official trail.  This section appears rarely used and bypasses the bottom that mountain bikers prefer.  The trail levels out near the highway junction, passing through open-sage flats before emerging at the Stump Hollow trailhead.  Once the group reached the Beaver Mountain turnoff parking area, one driver took the other carpool drivers to recover their vehicles at the starting point so they could return and pick up their riders for the return to Logan.   

Overall, this hike took just over 5 hours at a leisurely pace, with only a few mountain bikers and hikers encountered along the way. It's a gem for experiencing Logan Canyon's diverse ecosystems—from sagebrush to subalpine forest—and the eerie beauty of Peter Sinks.

Trip Summary:
  • Thirteen hikers: Brent J., Brent L, Bruce, Dave P, Jane, Jim, Kamren, Laurel, Nancy, Sue, Susan, Teresa, and Ralph (leader)
  • Drove 35  miles to the South Sink parking area.
  • Started hiking at about 9:00 am; lunch from 11:30 to 12:00 pm; completed hiking at 2:15 pm.
  • Great hiking conditions: bluebird day with a few clouds, mild temperatures, early fall colors, mild breezes, and minimal insects.
  • Approximately 9 miles and 1,100 feet of elevation gain

Thanks to Ralph for the narrative, photos and GPS data, Dave P, Kamren and Jane for photos, and Teresa for GPS data.

   
Starting out from South Sink

Hikers on lower Burnt Fork trail


Evidence of past logging in lower Burnt Fork
 		This green darner dragonfly was too cold to fly


A mountain bike jump in lower Burnt Fork
 		A Burnt Fork geology talk
The terrain opened in upper Burnt Fork We could see the "Sink" weather station from the ridge

Bear Lake view from the ridge


The "Rim" weather station
 		"Rim" and "Sink" temperatures were both 56 ºF

Cold sink temperatures cause an inverted tree line, where normal trees grow above stunted krummholz trees
Looking up from the sink bottom
 		A cool, mossy opening at the bottom of the sink
A lunch stop along the Stump Hollow trail


Peaks of the Bear River Range:  Beirdneau Peak (left) and Mt. Elmer (right)

Peaks of the Bear River Range:  Mount Magog and Mount Gog (left) and Doubletop Mountain (right)


An elk wallow and nearby hunter's tree stand


Oriole? nest
 		Lupine

Our GPS tracks show about 9 miles with 1100 feet of ascent for hikers going to the sink bottom (red) and about 8.5 miles with 900 feet ascent for others (blue). You can look at our route using Google Earth or download our GPS file.