Lassen Volcanic National Park protects 106,452 acres in northeastern California. The centerpiece of the park is Lassen Peak, the largest plug dome volcano in the world. A plug dome volcano is made of solid lava. After the volcano erupts, lava fills up the vent and continues to flow for years or centuries, building up a huge dome. However, scientists believe that Lassen Peak formed relatively quickly in just a few years.
Lassen Peak is the southern-most active volcano in the Cascade Volcanic Arc, which stretches north into British Columbia. The 10,462-foot Lassen Peak was created on the northeastern flank of Mount Tehama, an even larger stratovolcano that stopped erupting about 400,000 years ago, and has since eroded away, especially from glaciers during the numerous ice ages. This photo shows Lassen Peak reflecting off Manzanita Lake.
This photo shows Chaos Crags, the youngest group of lava domes in the park. It consists of five domes that formed about 1,000 years ago. About 300 years ago, a large rock avalanche plowed down Chaos Crags at about 100 miles per hour, flattened the forest, and dammed Manzanita Creek, creating the Manzanita Lake as shown. Do you notice the fisherman on the lake? (Click on the photo for a larger version.) He was sitting on a raft with his feet in the cold water. We spoke with his wife, who said this position was much more comfortable than sitting in a boat for long periods, and their feet didn’t get that cold with thermal socks.
Lassen Peak’s eruption in 1914 started a three-year period of activity. On May 22, 1915, the largest eruption blew a huge mushroom cloud of ash 30,000 feet into the air. The hot lava instantly melted the snow on the peak, creating a half-mile-wide avalanche of snow, lava and rocks that raced down the volcano.
“In the night his dog barked, raved, and stuck his paws against him to wake him up. Elmer thought it might be a bear or panther, so he got up. He peeped out to see what the dog was barking at. He saw the mud flow coming like a wave about twelve feet high.” Elmer Sorahan narrowly escaped the flood, then ran three miles to warn others. Thanks to Elmer’s heroics, no lives were lost, but six houses were destroyed by the flood. This photo shows Lassen Peak above the pretty Upper Meadow.
The circular formation in the rock is Vulcan’s Eye. This section of rock that contains Vulcan’s Eye is what the entire Lassen Peak volcano used to look like: layers upon layers of lava. You can see Vulcan’s Eye in the top photo as well, and more of Lassen Peak, which has eroded over time to a relatively smooth surface. You can also see the trail we hiked up to Lassen Peak.
The trail up Lassen Peak was steep but offered terrific views the entire hike.
Much to our disappointment, the final mile of the hike to Lassen Peak was closed because the park service was rehabilitating the trail. We’re happy that they are improving the trail, but did they have to close the trail while they work on it? It turns out the trail is open for just a few days each month, they’ve been working on it for a couple years, and they don’t expect to finish their work until 2016! This was one of the dumber things we’ve heard on our trip. The park service could take a lesson from road construction crews that do their best to keep roads open and traffic flowing.
Here are Eagle Peak (left) and Lassen Peak (right) rising above the beautiful deep blue Lake Helen.
Although the last eruption was in 1917, the park is still quite active geologically. This photo shows the Sulphur Works mud pot. A mud pot is an acidic hot spring. Acid and micro-organisms decompose surrounding rock into mud, which mixes with a limited amount of water from an underground spring to form a thick slurry. Extremophile micro-organisms are capable of surviving in extremely hot environments that would be deadly to most life on Earth. Sulphur Works is the volcanic center of ancient Mount Tehama and is named after the strong rotten-egg smell of hydrogen sulfide.
Bumpass Hell is a 16-acre geothermal area that has hot springs, boiling pools, fumaroles (steam & gas vents) and mud pots. Bumpass Hell is not connected to Mount Tehama’s main vent, and instead is driven by fissures three miles below the surface that allow volcanic heat to escape.
Bumpass Hell was named after a cowboy who worked nearby in the 1860s and discovered the area by chance. While exploring the geothermal features, Bumpass broke through the thin crust above a mud pot and badly scalded his leg. He told townspeople about the incident and described it as “hell.” A newspaper editor convinced Bumpass to show him where his accident had occurred. On the return trip, Bumpass’ leg broke through the crust again, and this time it had to be amputated! Fortunately now there are elevated boardwalks for tourists to view the thermals without fear of amputation.
Many of these pools approach the boiling point at their altitude, which is 198 degrees F at Bumpass Hell. Temperatures as high as 230 degrees F have been recorded in the park.
Hot springs change form during the year. In early summer, abundant water from melting snow results in clear springs. As the summer progresses and the water supply decreases, springs turn into mud pots and eventually into steaming fumaroles.
Cinder Cone is a 750-foot tall cinder cone volcano that spread ash over 30 square miles. Its age has been controversial since it was first discovered in the 1850s, but carbon dating of trees killed by the eruption indicate the cinder cone was formed in just a few months during the 1650s. The crater is 1,000 feet in diameter and 230 feet deep. We climbed to the top of the cone and then hiked down into the crater, where there is a large pile of rocks.
The Cinder Cone eruption was eventually snuffed out by several basalt flows that erupted from its base. These flows resulted in the Fantastic Lava Beds, which dammed creeks to create a few lakes including Butte Lake, shown in the photo above. In the foreground are the colorful Painted Dunes.