Sept. 23, 2020 – The fourth Saturday in September is National Public Lands Day. Many admission fees are waived at national parks and other public lands so it’s the perfect day to escape from COVID-19 life. Explore wide open spaces where it is easy to practice social distancing.

Redwood Learn visited Lassen Volcanic National Park in northern California in 2015. We took a hike that passed through boiling mudpots, fumaroles, and other amazing geologic features. The park celebrated its Centennial in 2016. Imagine exploring the park in 1916!

The park was intriguing just from scrolling through Lassen’s website. Pictures of boiling mudpots and fumaroles were strange and interesting. As soon as the park description mentioned that all four types of volcanoes are found in the park, it was a location Redwood Learn had to visit!

History
During the Gold Rush in the 1840s and 1850s, millions of people migrated westward to find their fortunes. In 1864, Kendall Bumpass and a friend explored the area. They were thinking about opening a portion of it as a public attraction. Little did they know the steaming mud pots and fumaroles around them were among the most caustic in the world. Kendall stepped into a boiling mud pot and lost his leg. He had stepped into very hot acid. Plans to open a public attraction ended.

Fumaroles are breaks (fizzures) in the ground through which steam and sulfur gas (hydrogen sulfide) escape. This geologic feature is the result of hot magma underground combining with water.

The last eruptions of Lassen Peak occurred between 1914 and 1921. The largest explosion occurred on May 22, 1915. Benjamin Loomis, a local businessman, took photos of the 1915 eruption.

The photos captured of the eruption convinced authorities to preserve the area. The park was set up on Aug. 9, 1916, just days before the U.S. Congress voted to establish the National Park Service (NPS) system.

According to NPS, every rock in the park originated from volcanoes. A hike not to miss is the “Bumpass’ Hell Trail.” It’s named after Kendall Bumpass.

The hike is a walk through geologic and American history. From the trailhead, hikers walk next to beautiful wildflower meadows, hug the side of mountains at 8,000 feet above sea level and then descend to a hydrothermal basin. The basin looks like the Red Planet – Mars. Fortunately, there is a boardwalk in the basin. It passes over the acidic, boiling mudpots. In 2018, the park closed the boardwalk for renovation. It’s open now but will close soon for the winter.

Four types of volcanoes*

The four types of volcanoes defined by geologists are: 1) lava dome, 2) shield, 3) composite and 4) cinder cone.

Lava (Plug) Dome
Lassen Peak is a plug dome volcano. According to the U.S. Geological Survey (USGS), volcanic or lava domes are formed by relatively small, bulbous masses of lava too viscous to flow any great distance. Because of the viscosity, as the flow pushes out, lava piles over and around its vent. A dome grows largely by expansion from within. As it grows, its outer surface cools and hardens, then shatters. Lloose fragments spill down its sides. Some domes form craggy knobs or spines over the volcanic vent. Others form short, steep-sided lava flows. These are known as “coulees.” Volcanic domes commonly occur within the craters or on the flanks of large composite volcanoes.

Shield Volcano
Mount Harkness in Lassen is an example of a shield volcano. Mount Harkness began forming about 600,000 years ago. A shield volcano is a broad, rounded volcano. It’s built up by successive outpourings of very fluid lava that can spread over great distances.

According to the USGS, the successive lava flows in a shield volcano builds a broad, gently sloping cone. The cone looks like a warrior’s shield. Rift zones develop because of fractures on the flanks of the cone. Lava erupts from vents in these fractures. Some of the largest volcanoes in the world are shield volcanoes. In northern California and Oregon, many shield volcanoes have diameters of 3 or 4 miles and heights of 1,500 to 2,000 feet. The Hawaiian Islands are composed of linear chains of shield volcanoes, including Kilauea and Mauna Loa on the island of Hawaii – two of the world’s most active volcanoes. The floor of the ocean is more than 15,000 feet deep at the bases of the islands. Mauna Loa is the largest of the shield volcanoes (and also the world’s largest active volcano). It projects 13,677 feet above sea level. Its top is over 28,000 feet above the deep ocean floor.

Composite Volcano
Brokeoff Mountain in Lassen is a composite volcano. It has layers of volcanic rock, lava, cinders, and ash that have erupted from a central vent or group of vents. Brokeoff Mountain in Lassen is a remnant of the park’s only composite volcano, the larger Brokeoff Volcano.

According to the USGS, some of the Earth’s most majestic mountains are composite volcanoes. Composite volcanoes are also called stratovolcanoes. Composite volcanoes can rise as much as 8,000 feet above their bases. Some of the most conspicuous and beautiful mountains in the world are composite volcanoes, including Mount Fuji in Japan, Mount Cotopaxi in Ecuador, Mount Shasta in California, Mount Hood in Oregon, and Mount St. Helens and Mount Rainier in Washington.

Cinder cone volcano
Cinder Cone volcano in Lassen is an example of a cinder cone volcano. It’s made up of loose volcanic rock, cinders, and ash that accumulates around a single vent. Lassen’s Cinder Cone volcano formed during eruptions hundreds of years ago (around 1650). Its elevation is from 6,061 to 6,907 feet above sea level.

Cinder cones are the simplest type of volcano. They are built from particles and blobs of congealed lava ejected from a single vent. As the gas-charged lava is blown violently into the air, it breaks into small fragments. These fragments solidify and fall as cinders around the vent to form a circular or oval cone. Most cinder cones have a bowl-shaped crater at the summit. Cinder cone volcanoes rarely rise more than 1,000 feet or so above their surroundings. Cinder cones are numerous in western North America as well as throughout other volcanic terrains of the world.

Visit Lassen for a geologic lesson like no other! But leave the flip-flops at home and bring the hiking boots for a walk or hike on geologic history!

*Information from the National Park Service (NPS) and the U.S. Geological Survey (USGS)

REVIEW QUESTIONS

1. What are the four types of volcanoes?

2. Where is Lassen Volcanic National Park located? When was it established (founded)?

3. When was the last time the Lassen Peak volcano erupted?

INQUIRY QUESTIONS

1. Study the main picture. Why are some of the rocks yellow?

2. At what temperature does water boil? Compare, in quantitative terms, to the temperature of the mudpots.

3. Choose one of the four types of volcanoes. Research and write a summary of an example of that type of volcano located elsewhere.

4. Why is Lassen Volcanic National Park a great spot for geologists to study volcanoes?

5. Why do you think Kendall Bumpass thought Lassen could be a public attraction in 1864?

8. How does the text support the photos of the four types of volcanoes? Write a summary.

9. From information in the story, is Lassen Peak or Cinder Cone mountain higher in altitude?

10. Read the headline again. What is the figurative meaning of “Take a Hike?” Why is the headline a literal meaning?