Lassen Volcanic National Park
Lassen Volcanic National Park in northern California illustrates Earth’s powerful forces. Every rock found in the national park has its origin in volcanic activity and all four types of volcanoes are found in the park: shield, composite, cinder cone, and plug dome. Lassen lies at the crossroads of three biological regions: the Cascade Range to the north, the Sierra Nevada mountains to the south, and the Great Basin desert to the east. This convergence contributes to the diversity of ecosystems and the abundance of flora and fauna found in the park including over 745 distinct species like the extremely rare small rodent called the American pika. Unlike many national parks where forces created the landscape thousands of years ago, the forces that created Lassen Volcanic National Park are both ancient and recent.
At 10,457 feet, Lassen Peak in the center of the park is one of the largest plug dome volcanoes in the world. A plug dome volcano forms when lava is too thick to flow great distances. Lassen Peak experienced a period of severe activity between 1914 and 1921. Late on the evening of May 19, 1915, a large steam explosion shattered the lava that had filled Lassen Peak’s crater the previous five days. Glowing blocks of hot lava fell on the summit and snow-covered upper flanks of the volcano setting off an avalanche of snow and lava rocks a half-mile wide. The volcano’s crater welled up again with lava and late on the afternoon of May 22, 1915, Lassen Peak blew again with even more force. The blast hurled rock fragments and pumice high into the air. A huge column of volcanic ash and gas rose more the 30,000 feet and could be seen 150 miles away. The falling pumice created yet another avalanche, this time a pyroclastic flow of hot ash, pumice, rock fragments, and gas. The entire east face of Lassen Peak had been blown away and the landscape was forever changed. The eruptions in 1915 were photographed by local businessman Benjamin F. Loomis and paved the way to the creation of Lassen Volcanic National Park on August 9, 1916.
Some 350 years ago, an enormous rock avalanche called the Chaos Jumbles forever altered the landscape of Lassen Volcanic National Park. The entire northwest face of a cluster of volcanoes known as Chaos Crags broke loose three times in close succession with debris collapsing and sliding down the mountain’s slope. The rubble traveled with such a force and speed that it washed 400 feet up the slope of Table Mountain which is four miles away! The forest below the slope was buried by feet of rubble and today the forest is just starting to recover with trees growing out of the rubble. It is really a surreal landscape to stand upon.
There is still plenty of evidence of active volcanism below the surface of Lassen Volcanic National Park. Rain and snow feed the extensive hydrothermal system that lies deep underground. Heated by molten rock, this water rises to surface creating remarkable features found throughout the park. Just adjacent to the road near the southern entrance, steaming fumaroles and boiling mudpots are visible at Sulphur Works. The Bumpass Hell section of the park features a boardwalk which takes guests out over the hydrothermal features while boiling cauldrons can be found at Devil’s Kitchen in Warner Valley of the park.
Located just outside the national park in the Lassen National Forest is a geological feature known as the Subway Cave lava tube. Some 30,000 years ago, lava began spewing from deep cracks in the earth and rivers of molten, red-hot rock flowed for 16 miles in the Hat Creek Valley. While the top crust of the flow cooled and hardened, rivers of red-hot lava continued to flow underneath insulated by the rock above. Eventually the lava drained away, leaving behind tube like caves. While many of the lava tubes have long since collapsed, Subway Cave is a quarter of a mile section of the lava tub that is easily accessible. Visitors can enter the cave via stairs at one end and explore the inside of the lava tube with the aide of a flashlight. The walls and ceiling are smooth and almost appear to be a concrete-lined tunnel, while the floor is uneven with sharp volcanic rock.
The 33-mile Lassen Volcanic National Park Highway offers access to trails, lakes, and volcanic and hydrothermal features throughout the park. The highway begins at the western park entrance where you find the beautiful Manzanita Lake along with the Loomis Museum and campground. As you travel southeast on the highway, you drive through the Chaos Jumbles and the devastated area of the 1915 eruption of Lassen Peak. The spectacular Upper Meadow is a stop along the highway just before you begin climbing to the highest point on the route which is at the Lassen Peak Trailhead at 8,512 feet. As you descend back down, there are several gorgeous alpine lakes with crystal clear, emerald blue waters: Lake Helen and Emerald Lake. Towards the southern end of the highway, you enter the active hydrothermal region of the park with Bumpass Hell and Sulphur Works accessible from parking areas off the highway.
