Longstreet Highroad Guide to the California Sierra Nevada
By Mark Grossi
[Fig. 7] Just north of the Sierra Nevada, the Cascade Range's southernmost volcanic formations make the perfect bookend to the Sierra's granite. The showcase in the southern Cascades is Lassen Volcanic National Park where 10,457-foot Lassen Peak was active less than a century ago.
Though it is not a part of the Sierra, this national park is well worth the slight detour. Its explosive past and its current volcanic features should not be missed in any tour of Northern California.
The last major eruption at the park occurred when Lassen Peak began explosions at irregular intervals in 1914. By May 19, 1915, lava rose in the summit crater, spilling over the northeastern and southwestern sides. The glowing lava cooled and hardened before it reached the Sacramento Valley, but it caused a stir.
The lava melted snow and cut a fiery swath through forested land. On May 22, 1915, people from the valleys to the mountains could see a 40,000-foot-high volcanic cloud rising. A massive explosion had blown a new crater in the mountain. People in towns such as Redding were in a panic.
Today, the volcano is quiet, except for steam occasionally rising from the summit and flanks of the mountain. Light streaks of dacite and dark markings of andesite are prominent in the pumice that was ejected from the 1915 blast.
In Lassen, hot springs remain as reminders of the molten past. Temperatures as high as 230 degrees Fahrenheit have been recorded at some springs. The springs are called Bumpass Hell, Sulphur Works, Little Hot Springs Valley, Cold Boiling Lake, and Devil's Kitchen in Warner Valley.
Gases in the hot springs contain carbon dioxide and steam. Surrounding rocks usually contain sulphur, iron pyrite, quartz, and other substances. Four types of lava are found in the park, including rhyolite and dacite (light-colored lavas) and basalt and andesite (both of which are darker).
Lassen Peak, a Pelean-type plug dome volcano, pushed its way up about 27,000 years ago. The "plug" simply refers to the hardened magma lodged in the eroding cone. "Pelean" is the type of volcanic eruption that occurred in 1915, which scientists believe was similar to the 1902 eruption of Mont Pelée on Martinique, Lesser Antilles. Incandescent lava fragments were blown out of a central crater. In this type of eruption, a tongue-like, glowing avalanche then moves downslope at velocities as great as 100 miles per hour.
Such volcanic activity has been happening for 70 million years, dating back to the time the area was still covered by the Pacific Ocean. The volcanic activity was stimulated by the collision of the North American and Pacific tectonic plates, which began about 200 million years ago.
Lassen Peak and the other 16 major volcanoes of the Cascades are part of the "ring of fire" surrounding the Pacific Ocean. The "ring of fire" is a series of volcanoes that circle the Pacific tectonic plate spreading thousands of miles, including Hawaii and other parts of the South Pacific as well as the Pacific Northwest. The eastern side of the Sierra is also included in the circle.
The Cascade Range, where the park is located, is younger than the nearby Sierra by more than 100 million years. The range began in the Lassen Strait, a depression that broadened millions of years ago and eventually rose to separate the Sierra Nevada and the Klamath Mountains, which were believed to be one continuous range at one time.
Touring the park's main road, Lassen Park Road, which connects with Highway 89, people can see Lassen's 106,000 acres of volcanic beauty. The 150 miles of hiking trails include 17 miles of the Pacific Crest Trail.
Lassen's varied landscapesvolcanic, high altitude, meadow, rocky canyon, and othersprovide support for more than 700 flowering plant species and 250 vertebrates. In the forests above 7,000 feet, the park's red fir (Abies magnifica) belt supports fewer species of animals because there is not enough plant life and other food sources for such creatures as the striped skunk (Mephitis mephitis), which prefers grasshoppers, beetles, and other surface insects that are not as abundant at high elevation as they are farther down the mountains.
At elevations above 8,000 feet, the whitebark pine (Pinus albicaulis) can be found in drier, south-facing parts of the park. The mountain hemlock (Tsuga mertensiana) lives in similar elevations, but it grows best in shady, moister conditions, thriving in places where the snow lingers well into summer.
The Douglas fir (Pseudosuga menziesii) is perhaps the tree most associated with the national park and with the forest surrounding it. Blue grouse (Dendragapus obscurus) and mule deer (Odocoileus hemionus) eat its long, dark, yellow-green needles. The tree can grow up to 200 feet. In logging areas outside the national park, it is a favorite for use as a Christmas tree.
The midelevations, between 5,000 and 7,000 feet, are home to old-growth trees ranging from ponderosa or yellow pine (Pinus ponderosa) to the firs, including the white fir (Abies concolor) and the Douglas fir. These trees are important in the ecosystem as habitat for such rare creatures as the spotted owl (Strix occidentalis), considered a sensitive species that must be protected in California. The owl nests in cavities of old-growth trees with diameters of 40 inches and bigger.
Old-growth tree stands contain trees that are centuries old and sometimes 200 feet tall. Most often, the stands contain downed trees that have fallen over time because of insect infestation, lightning strikes, or age. The trees can often remain in the ecosystem for hundreds of years, decomposing and providing places for wildlife to live or find refuge. As trees decompose, they also add nutrients to the soil.
Such stands of trees are becoming rare in California because many of them have been heavily logged. In Lassen National Park, as in Yosemite and Sequoia and Kings Canyon national parks, logging has been forbidden for many decades, so the national parks have the largest remnants of old growth.
In the lower elevations near pools of water along streams, look for the thumb-sized leaves of the Douglas spiraea (Spiraea douglasii) and the greenish-gray leaves of the western blueberry (Vaccinium uglinosium ssp. occidentale). The edible fruit of the western blueberry may be found in late spring.
Plan any trip to Lassen with the weather in mind. The roads into the park can be closed due to snowy conditions.
[Fig. 7(1)] The volcano may have blown its top early this century, but it is not active now. The four-hour day hike to Lassen Peak is a strenuous trip, but it is well worth the view of this volcano, which was formed on a vent of Mount Tehama. There is no water, so carry your own.
From the Lassen rim at more than 10,450 feet, the views are spectacular. See Chaos Crags, Reading Peak, and Brokeoff Mountain. In the distance to the north, there is the Modoc Plateau. Lake Almanor is quite clear to the south. And, it seems like the whole Northern Sierra spreads in view for perhaps 100 miles on a clear day.
Large animals, such as the California black bear (Ursus americanus), do not generally climb much beyond the tree line, which is about 9,000 feet. Still, hikers will see animal life above 10,000 feet on Lassen Peak Trail. Look for the yellow-bellied marmot (Marmota flaviventris), the largest ground squirrel in the park. It prefers the higher elevations, which provide refuge from large predators.
In the warmer months, hikers need only take a deep breath to smell the coyote mint or pennyroyal (Monardella villosa). High elevation winds waft the mint aroma from bunches of these white flowers, which often provide the only color at the higher elevations of this trail. Native Americans ingested mild doses of this flower to relax.
[Fig. 7(2)] The trail to Bumpass Hell goes to Cold Boiling Lake and Crumbaugh Lake. At Cold Boiling Lake, bubbles are often seen rising to the surface from the release of gas underground beneath the lake.
But the real show is at Bumpass Hell, where groundwater seeping into an underground magma chamber heats and rises. Walk the boardwalk and watch the mud pots and steam vents in this eerie place.
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