A corner of Manzanita Lake at Lassen Volcanic National Park in Shasta and Lassen counties, California.

The source of heat for volcanism in the Lassen area is subduction off the Northern California coast of the Gorda Plate diving below the North American Plate. The area surrounding nearby Lassen Peak is still active with boiling mud pots, stinking fumaroles, and churning hot springs. Lassen Volcanic National Park is one of the few areas in the world where all four types of volcano can be found (plug dome, shield, cinder cone, and strato).

White immigrants in the mid-19th century used Lassen Peak as a landmark on their trek to the fertile Sacramento Valley. One of the guides to these immigrants was a Danish blacksmith named Peter Lassen, who settled in Northern California in the 1830s. Lassen Peak, and the park, were named after him.

Inconsistent newspaper accounts reported by witnesses from 1850-1851 described seeing "fire thrown to a terrible height" and "burning lava running down the sides" in the area of Cinder Cone. As late as 1859 a witness reported seeing fire in the sky from a distance, attributing it to an eruption. Early geologists and volcanologists who studied the Cinder Cone concluded the last eruption occurred between 1675 and 1700. After the 1980 eruption of Mount St. Helens, the United States Geological Survey (USGS) began reassessing the potential risk of other active volcanic areas in the Cascade Range. Further study of Cinder Cone estimated the last eruption occurred between 1630 and 1670. But smooth, black, volcanic rocks can still be seen strewn across meadows and forestland throughout Northeast California. Photo by Carol Highsmith, 2012.