When molten rock spews up so slowly from a volcano that it cools before it has a chance to flow, it effectively plugs the opening it escaped from forming a bulge geologists refer to as a plug dome. At 10,457 feet in elevation, the largest plug dome volcano in the world is Lassen Peak, also called Mount Lassen, the centerpiece of Lassen Volcanic National Park in northern California.
While Lassen Volcanic National Park is a haven for campers, back packers, equestrian campers, hikers, mountain bikers, fishermen, bird watchers and outdoor lovers of all sorts, its chief fame comes from the fact that from a geological perspective, the park is one of the most interesting places on the planet. No fewer than four different types of volcanoes are to be found within its boundaries, as well as striking examples of associated volcanic topography.
Lassen Volcanic National Park is open all year round, but access is severely limited during the snowy winters when the Main Park Road only opens to the southwest portions of the park. The best time to plan a visit is mid-June through mid-September when the days are sunny and warm even if snow still lingers on the highest peaks.
Lassen Volcanic National Park is served by a full service visitor center near its southwest entrance and boasts ten campgrounds, some of which can accommodate small RVs. The campground fee generally runs $16 per night and most campgrounds are equipped with campfire rings with grills, bear-proof storage boxes, picnic tables and vault toilets. Four of the campgrounds operate on a first come, first served basis.
The History of Lassen Volcanic National Park
The area now known as Lassen Volcanic National Park was on the summer migratory route of four Native American tribes, the Atsugewi, the Yana, the Yahi, and the Maidu, whose descendents still live in the region.
Lassen peak is named for Peter Lassen, a Danish blacksmith who guided settlers through the volcanic terrain and down into the Sacramento Valley in the 1830s.
Lassen Peak went through a period of activity between 1914 and 1921 that included mudslides (lahars,) steam explosions, lava flows and volcanic eruptions. The largest eruption in 1915 was so forcible that it expelled ash all the way into Nebraska.
The Geology of Lassen Volcanic National Park
Lassen Peak in Lassen Volcanic National Park is the southernmost volcano in the Cascade Range, a volcanic arc that extends all the way from southern British Columbia through Washington and Oregon into northern California. Many geologists consider the area around Lassen Peak, with its mud pots, fumaroles and sulfur springs, and nearby Mount Shasta to be the two most likely sites for the next volcanic eruption in the United States.
Three other types of volcanoes occur in Lassen Volcanic National Park in addition to Lassen Peak. Hat Mountain, Cinder Cone and Red Cinder Cone are examples of cinder cone or ash cone volcanoes, the steep-sided volcanoes formed when molten rock erupts explosively from the earth’s core under high pressure. Mount Tehama is an example of a composite cone, or stratovolcano, formed from alternating layers of magma, rock fragments, and ash. Finally Prospect Peak, Mount Harkness, and Red Mountain are examples of shield cones created when low viscosity magma flows slowly from the earth’s interior over an extended period of time.
Other Recreational Opportunities in Lassen Volcanic National Park
Lassen Volcanic National Park contains over 150 miles of hiking trails, winding past thermal areas, old growth forests and alpine tundra. Hikers are well advised to stay on trails and use boardwalks when provided, both to minimize disturbance to the environment and for safety reasons as the crust over the region’s many thermal features can be quite thin in places.
Horses are allowed on all but a few of the designated hiking trails within Lassen Volcanic National Park, and two of the campgrounds are outfitted with corrals. The fee for overnight stay for a horse is $4 per night.