Mount Shasta

Mount Shasta, a 14,162-foot (4,322 m) stratovolcano, is the second-highest peak in the Cascade Range and the seventh-highest peak in California. ^* The mountain is located in Siskiyou County, and has an estimated volume of 108 mile³ (450 km³). Physically unconnected to any nearby mountain, and rising abruptly from miles of level ground which encircles it, Mount Shasta stands some 10,000 feet (3,000 m) above the surrounding area. Shasta was memorably described by the poet Joaquin Miller, "Lonely as God, and white as a winter moon, Mount Shasta starts up sudden and solitary from the heart of the great black forests of Northern California."

Geology

The mountain consists of four cones contained atop one another; these overlapping cones have built a complex shape making up the main body of the major summit. In addition, there is a lesser summit, named "Shastina;" Shastina is 12,300 ft (3,749 m) tall and has the most visible conical shape (see image on left). Shasta's surface is relatively free of glacial erosion except, paradoxically, for its south side where Sargents Ridge runs parallel to the U-shaped Avalanche Gulch (the largest glacial valley on the volcano, although it does not presently have a glacier in it)(see image on left). There are five named, yet small, glaciers clustered on the mountain's north side.

There are many buried glacial scars on the mountain which were originally excavated in glacial periods ("ice ages") of the present Wisconsinian glaciation. Most have since been filled-in with andesite lava, pyroclastic flows, and talus from lava domes. Shastina, by comparison, has a fully intact summit crater indicating that Shastina developed after the last ice age.

About 593,000 years ago andesitic lavas erupted in what is now Mount Shasta's western flank near McBride Spring. Over time an ancestral Shasta stratovolcano was built to an unknown height but sometime between 300,000 to 360,000 the entire north side of the volcano collapsed, creating an enormous landslide, 6.5 mile³ (27 km³) in volume. The slide flowed northwestward into Shasta Valley where the Shasta River now cuts through the 28 mile (45 km) long flow.

The remains of the oldest of Shasta's four cones is now exposed at Seageants Ridge on the south side of the mountain. Lavas from the Sargeants Ridge vent cover the Everitt Hill shield at Shasta's southern foot. The last lavas to erupt from the vent were hornblende-pyroxene andesites with a hornblende dacite dome at its summit. Glacial erosion has since modified its shape.

The next cone to form is presently exposed south of Shasta's current summit and is called Misery Hill. It was formed 15,000 to 20,000 years ago from pyroxene andesite flows and has since been intruded by a hornblende dacite dome.

Since then the Shastina cone has been built by mostly pyroxene andesite lava flows. 9500 years ago these flows reached some 6.8 miles (11 km) south and three miles north of the area now occupied by nearby Black Butte (see below). The last eruptions formed Shastina's present summit about a hundred years later. But before that, Shastina, along with the then forming Black Butte dacite plug dome complex to the west, created numerous pyroclastic flows that covered 43 mile² (110 km²), including large parts of what is now Mt. Shasta, California and Weed, California. 400 ft (120 m) deep and quarter-mile (400 m) wide Diller Canyon is an avalanche chute that was probably carved into Shastina's western face by these flows.

The last to form and highest cone, the Hotlum Cone, formed sometime before 8000 years ago. It is named after the Hotlum glacier on its northern face and its longest lava flow, the 500 ft (150 m) thick Military Pass flow, extends 5.5 miles (9 km) down its northwest face. Since its creation a dacite dome intruded the cone and now forms the summit. The rock at the 600 ft (180 m) wide summit crater has been extensively hydrothermally altered by sulfurous hot springs and fumaroles there (only a few examples still remain).

In the last 8000 years, the Hotlum Cone has erupted at least eight or nine times. About 200 years ago the last significant Shasta eruption came from this cone and created a pyroclastic flow, a hot lahar (mudflow), and three cold lahars, which streamed 7.5 miles (12 km) down Shasta's east flank via Ash Creek. A separate hot lahar went 12 miles (19 km) down Mud Creek.

Volcanic hazards

During the last 10,000 years Shasta has erupted an average of every 800 years but in the past 4500 years the volcano has erupted an average of every 600 years. The last significant eruption on Shasta may have occurred 200 years ago.

Mount Shasta can release volcanic ash, pyroclastic flows or dacite and andesite lava. Its deposits can be detected under two nearby small towns totalling 20,000 in population. Shasta has an explosive, eruptive history. There are fumaroles on the mountain, which show that Shasta is still alive.

The worst case scenario for an eruption is a large pyroclastic flow, such as what occurred in the 1980 eruption of Mount St. Helens. Since there is ice, lahars would also result. Ash would probably blow inland, perhaps as far as eastern Nevada. There is a small chance that an eruption could also be bigger resulting in a collapse of the mountain, as happened at Mount Mazama in Oregon, but this is of much lower probability.

The United States Geological Survey considers Shasta a volcano with a high probability of erupting again.

History

The oldest human habitation in the area dates to about 7000 years ago, and by about 5000 years ago, there was substantial human habitation in the surrounding area.

At the time of Euro-American contact in the 1820s, the Native American tribes who lived within view of Mount Shasta included the Shasta, Okwanuchu, Modoc, Achomawi, Atsugewi, Karuk, Klamath, Wintu, and Yana tribes.

Although perhaps first seen by Spanish explorers, the first reliably-reported sighting of Mount Shasta by a European or American was by Peter Skene Ogden (a leader of a Hudson's Bay Company trapping brigade) in 1826. In 1827, the name "Sasty" or "Sastise" was given to nearby Mount McLoughlin by Ogden. (The name was transferred to present-day Mount Shasta in 1841, as a result of work by the United States Exploring Expedition).

Beginning in the 1820s, Mount Shasta was a prominent landmark along what became known as the Siskiyou Trail, which runs at Mount Shasta's base. The Siskiyou Trail was located on the track of an ancient trade and travel route of Native American footpaths between California's Central Valley and the Pacific Northwest.

The California Gold Rush brought the first Euro-American settlements into the area in the early 1850s, including at Yreka, California and Upper Soda Springs. The first recorded ascent of Mount Shasta occurred in 1854 (by Elias Pearce), after several earlier failed attempts. Within a few years, Harriette Eddy (and party) became the first woman recorded at the summit.

By the 1860s and 1870s, Shasta was the subject of scientific and literary interest. The summit was achieved (or nearly achieved) by John Muir, Josiah Whitney, Clarence King, and John Wesley Powell. In 1877, Muir wrote a dramatic popular article about an experience in which he survived an overnight blizzard on Shasta by lying in hot sulphur springs found near the summit (Muir article).

The 1887 completion of the Central Pacific Railroad, built along the line of the Siskiyou Trail between California and Oregon, brought a dramatic increase in tourism, lumbering, and population into the area around Mount Shasta. Early resorts and hotels grew up along the Siskiyou Trail around Mount Shasta, catering to these early adventuresome tourists and mountaineers.

In the early Twentieth Century, the Pacific Highway followed the track of the Siskiyou Trail to the base of Mount Shasta, leading to still more access to the mountain. Today's version of the Siskiyou Trail, Interstate 5, brings thousands of people a year to Mount Shasta.

Today, the area remains one of California's premiere tourist destinations, attracting travelers from around the world.

Religion

The lore of some of the Native Americans in the area held that Shasta is inhabited by the spirit chief Skell who descended from heaven to the mountain's summit.

Many other faiths have been attracted to Shasta over the years -- more than any other Cascade volcano. Mount Shasta City and Dunsmuir, California, small towns near Shasta's western base, are focal points for many of these, which range from a Buddhist monastery (Shasta Abbey, founded by Houn Jiyu-Kennett in 1971) to modern-day Native American rituals. According to the Forest Service as reported in documentaries such as In The Light of Reverence, a group of Native Americans from the McCloud River area practice rituals on the mountain.

Guy Ballard's I Am Activity (started in the 1930s) and Elizabeth Clare Prophet's Church Universal and Triumphant (started in the 1950s) are probably the best-known among numerous groups to attempt to participate in, or redefine, Shasta's spiritual heritage. Some cults hold that races of sentient or spiritual beings, superior to humans, live in or on Shasta, or visit the mountain.

Mount Shasta City hosts 16 Christian churches. If the membership rolls were combined, they would account for approximately 25 percent of the population.

Cultural references

Frederick Spencer Oliver's fantasy novel, A Dweller On Two Planets, is about the Lemurian race. In the novel, Lemurians who traveled to Mount Shasta when their continent sank beneath the Pacific Ocean, are now said to live inside the mountain in a series of tunnels. Many people claimed to have encountered Lemurians on Shasta.
Mt. Shasta is mentioned in Lost Legacy, a speculative fiction short story by Robert A. Heinlein as the home of a group of men who are masters of psychic powers and who decide to teach the world their powers by enlisting Boy Scouts.
The mountain is also part of a key scene in Ken Grimwood's novel Replay.

References

External links

Mount Shasta Collection at College of the Siskiyous
Mount Shasta on Summitpost.org
Mount Shasta at Peakbagger.com
Shasta Cam provides a live view of Mt. Shasta updated every 20 minutes.
Mount Shasta on Bivouac.com
Sisson Museum/Mt. Shasta Museum
Museum of the Siskiyou Trail
Geological summary

Mount Shasta | Mount Shasta | シャスタ山 | Shasta (sopka)

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