Created in 1916, Lassen Volcanic National Park protects some of the most fascinating volcanic features to be found within the continental United States. Located in northeast California, this park encompasses well over a dozen Cascade Range volcanoes of all four major types (shield, composite, cinder, and lava dome). Even more interesting are the numerous active hydrothermal areas that feature steaming fumaroles and boiling mudpots. Set among some beautiful conifer forests and panoramic mountain views, Lassen is well worth a visit.
This national park gets a great deal of snow in the winter, with the highest elevations accumulating up to forty feet. A friend and I had intended to visit the park in December but tire chain requirements thwarted our plans. We made it out again in late April and although the roads approaching the park were clear, there was still quite a bit of snow sticking around within the park itself.
California State Route 89 runs the length of Lassen, but even in late April it was still closed. Snow removal crews had been at work for a month prior to our visit, but deep snow spanning several miles still blocked the road near the center of the park. Because of this we had to abandon our car at the south entrance and hike up the winding road on foot.
We ventured about two and a half miles up CA-89, eventually turning around at the far side of Diamond Peak in the top center of the photo above. The road continues to a high point of 8512 feet just south of Lassen Peak, making it the highest road in the Cascade Range.
Even in this limited area at the south end of the park we were able to see several of the volcanic peaks that dot the Cascade Range, including Mount Diller…
…and Diamond Peak, an old magma conduit:
Together these peaks represent the remnants of Brokeoff Volcano. Once over 11,000 feet in height and over seven miles in width at its base, this massive composite volcano began its life about 600,000 years ago. Over the next few hundred thousand years it eventually emptied its magma chamber and collapsed on itself, and erosion has since removed much of the remaining central caldera.
Beginning around 27,000 years ago, the namesake lava dome volcano known as Lassen Peak began to emerge from the northeast edge of the deceased Brokeoff Volcano. Lassen Peak last erupted from 1914-1921, with a massive explosion in 1915. This southernmost active volcano in the Cascades is a sight to behold:
Lassen is more than just impressive volcanic peaks, however. In many places there are active hydrothermal areas featuring steaming fumaroles and boiling mudpots. Near the south end of the park we were treated to the features of Sulfur Works, located near the center of Brokeoff Volcano’s caldera.
In these hydrothermal areas groundwater seeps down near magma and hot rocks below the surface. It becomes superheated and rises, ultimately escaping at the surface as steam:
In some places it bubbles up through water and mud, creating acidic and scalding mudpot cauldrons:
This superheated water carries volcanic gasses and minerals dissolved from the surrounding rock. The gasses acidify the mudpots and sulfurous compounds emit a foul stench. The dissolved minerals collect at the surface, staining the ground in various colors:
Although we were able to see a lot of cool stuff within a couple of hours at Lassen, there’s still a lot more to this national park. Cinder cones and a massive shield volcano cover the eastern side of the park, many other hydrothermal areas belch steam and boiling water, and numerous organisms inhabit the conifer and alpine ecosystems. It would be worth returning in the summer when the road is open to explore this park in more detail.