In 1851, two gold prospectors said they'd walked ten miles over rocks so hot their boots fell apart. A doctor reported seeing flames the winter before. Put together, the story seemed to place Cinder Cone's last eruption right around 1850, and for decades that's the date that stuck. Tree rings eventually proved everyone wrong, by nearly two centuries.
A 25-Year-Old Volcano, According to 1875
The story starts with two separate, secondhand reports from the early 1850s: prospectors describing scorched ground and a physician, Dr. O.M. Wozencraft, reporting flames visible in the winter of 1850 to 1851. In 1875, a San Francisco doctor named H.W. Harkness worked backward from those reports and concluded Cinder Cone was roughly twenty-five years old, meaning it had erupted right around the time the accounts described.
It was a reasonable guess built from the only evidence anyone had. It also turned out to be almost entirely wrong.
Plan Your Lassen Visit
Cinder Cone and the Painted Dunes sit in the park's quieter northeast corner, off Highway 44.
Open the Trip Planner1666, Confirmed Three Different Ways
In the 1930s, USGS volcanologist R.H. Finch used tree-ring analysis on trees growing in and around the cone and proposed two much older eruptions, in 1567 and 1666. Decades later, USGS researchers went back with tools Finch never had: radiocarbon dating of wood killed by the eruption, which narrowed the true date to somewhere between 1630 and 1670, and paleomagnetic evidence, which ruled out the 1850s date completely. A 2009 dendrochronology study added a third line of evidence, reading not just tree-ring widths but chemical signals, phosphorus, sulfur, and sodium, in Jeffrey pines growing in the volcanic debris, and confirmed 1666 with high confidence.
Today, hikers can walk the same ground the eruption actually reshaped. The trail to the cone's summit runs four miles round trip with 846 feet of elevation gain from the Butte Lake trailhead, passing the Painted Dunes, colorful pumice and ash fields near the cone's base that were oxidized by the heat of the same 1666 lava, at around the 1.2-mile mark.
- Round trip 4 MILES
- Elevation gain 846 FEET
- Trailhead BUTTE LAKE, OFF HIGHWAY 44
- Confirmed eruption date A.D. 1666
Facts checked against a US Geological Survey fact sheet on Cinder Cone's dating history, a USGS dendrochronology study confirming the 1666 eruption, and the National Park Service's own Hiking Cinder Cone trail page for distance, elevation gain, and trailhead details.
The prospectors weren't lying. They really did see something in 1850 or 1851, something scorched and strange enough to report. They just weren't looking at a fresh eruption. They were looking at a landscape still settling from one that happened nearly two centuries earlier, and it took tree rings, radiocarbon, and a magnetized rock record to finally say so.