NSS Convention ~ July 25-30, 2021

US Forest Service image - Mount Shasta

Mount Shasta - A Pocket History

  • By Bruce Rogers
  • San Francisco Bay Chapter, NSS

At an elevation of 14,179 feet, Mt. Shasta towers above the local terrain at Weed, CA, by nearly 11,000 feet. Local inhabitants have held this impressive stratovolcano in reverence since they first passed through and settled between 11,000 and 7,000 years ago. Indeed the Modoc, Wintun, and Shas-tic-a Indians named the peak Wai-l'ka (or Wyeka) meaning Great White One or Great Purity One. These Native Americans never climbed the peak, believing the gods lived there and it was disrespectful or even foolish to do so.

Franciscans exploring California

Fray Narciso Durán was born December 16, 1776, at Castellón de Ampurias, diocese of Gerona, Catalonia, Spain. He became a Franciscan at Gerona, May 3, 1792, and was ordained a priest, December 20, 1800, by Bishop Pedro Díaz y Váldez in the episcopal chapel at Barcelona. Three years later he and Fray Buenaventura Fortuny left Catalonia for Cádiz where they sailed for Vera Cruz, Mexico, on May 3, 1803, arriving there about July. Fray Durán was assigned to Missions San Jose and Santa Barbara in present-day California.

Click here to download his 1817 California exploration diary.

The first Caucasian to mention it was Spanish Fray Narciso Duran who described it on May 17, 1817 while on a junket up the Central Valley as "a great hill covered with snow." Peter Ogden, pioneer Hudson Bay Company trapper and explorer, named it Sastise after the local Indian tribe and their camps along what he called the Sastise River in 1826. After a brief interlude of calling the snow-capped mountain Rogers Peak, the US Exploration Party settled the matter by naming it Shasta in 1841.

The first Caucasian party to summit the peak was that led by Elias D. Pearce of the Yreka Water Company on August 14, 1854 after several unsuccessful attempts. The first all-woman's summit group climbed the mountain shortly thereafter in 1856, led by Harriet Eddy and Mary Campbell McCloud. In 1877, naturalist John Muir wrote of a rather exciting overnight summiting during a howling blizzard, surviving by "sleeping" in a summit sulfur spring. Even today, ascents of the 14,179-foot peak, while not technically difficult, require a major effort. Winter ascents are fewer since snow conditions can be brutal as during the Feb. 13-19, 1959 storm, which saw a world-record of 15.75 feet of snow accumulating from a single storm.

Mt. Shasta is the second highest peak and the most voluminous stratovolcano in the Cascade Range of the northwest US. Built mostly of andesite volcanic rock (the extrusive equivalent of the dark gray intrusive rock diorite), the initial volcano started erupting about 593,000 years ago. That volcanic cone built to an unknown height, but the entire north side of the volcano collapsed between 360,000 and 300,000 years ago. Parts of this huge mass of rock spread north as a huge landslide riding on a cushion of compressed air and reached the far northern end of Shasta Valley some 28 miles to the north. The debris field of disarticulated blocks and ash was calculated to be about 8,000,000 cubic yards of volcanic debris and had puzzled geologists until its true nature was finally revealed in the 1960's.

Whitney Falls Trail

The Whitney Falls Trail accesses the lower flanks of Mount Shasta's northwestern side. Although the trail was initially constructed to serve as an approach to the climbing route that ascends the Whitney Glacier, today it functions primarily as a hiking trail that leads to an overlook of Whitney Falls, one of the four named waterfalls on Mount Shasta. The reason for this change in function is twofold. The primary reason for the change is sporadic glacial debris flows that were released from the Whitney Glacier and burst violently down Whitney Creek. The trail is currently passable, but sporty. Photo by Bubba Suess, Discover Siskiyou.

Mt. Shasta has blown its top about every 800 years during the past 10,000 years, but a bit more frequently during the last 4,500 years with eruptions about every 600 years. The last major eruption was about 200 years ago at the time France annexed Madagascar. The French explorer, Jean-Francois de Galaup La Peruse, sailed by in 1786 on his way to disappear in the southwest Pacific somewhere near the Solomon Islands. La Peruse logged on September 7th, on his frigate Boussole, that he saw a tall mountain with its top on fire. Historians have disputed this, but the jury is still out. Historians claim the last radiocarbon dated eruption was in about 1250 AD, a few years after the Mongols invaded Europe, sacking Moscow and Kiev.

In any case, Mt. Shasta is quite capable of exploding with a magnitude equivalent to the Mt. St. Helens eruption in 1980. It is monitored by the USGS as a #4 - a "very high threat" volcano (#5 indicates the volcano is erupting... run for it!) Shasta is so explosive partly because it its silica-rich magma has a tendency to stick in place until its strength is overcome and then explodes rather than quietly flows downhill like the more civilized basalt of the adjacent Medicine Lake Volcano. This ill-mannered volcano is also prone to blowing its top partly because it sits at the edge of a fragment of the North American plate that is being twisted nearly 40° clockwise as the North American Plate collides with the Pacific Plate. The resulting fracturing tectonics has allowed a lot of magma to ooze up and cause havoc in the neighborhood.

During the years following its near total collapse, other smaller volcanic cones built the edifice skyward. The oldest remnant cone is located under Sergeants Ridge on the southern side of Shasta. Next youngest is adjacent Misery Hill, having formed between 15,000 and 10,000 years ago. Yet younger is the western slope satellite cone of Shastina, the third tallest Cascade volcano itself. Hotlum Cone, the youngest cone, formed about 8,000 years ago - about the time humans arrived in the region. It is the last of the volcanic cones making up Mt. Shasta, having formed of andesite at about 7,650 years ago. On a clear day, the tall, snow-clad and multiple-coned Mt. Shasta is visible from the northern reaches of California Central Valley some 140 miles to the south near Chico to far out at sea of California's coast.

Mount Shasta glaciers

Mount Shasta and Whitney Glacier in California, seen from the crater (Shastina). Hotlum Cone is the dark-colored peak, and makes up summit of Mount Shasta. Photo by C. E. Watkins, USGS

Click here to download the USGS publication: Volcanic hazards at Mount Shasta, California (1989).

Glaciers have heavily sculpted the upper 4,000 feet of Shasta. Between 1870 and 1900, records showed that the glaciers were fairly stable, their normal melting of their lower end being balanced by constant additions to the upper core. At the end of this period, a few years of record snowfall allowed the glaciers to surge forward. The following twenty years were drought years on Shasta and the glaciers shrank, with the Wintun glacier nearly wasting away. Since about 1936, favorable snowfall has allowed a return to nearly 1870 conditions (1870 was the first year scientific reports about the mountain and its cadre of glaciers was written by pioneer geologist Clarence King). Despite the current drought climatic changes, however, these glaciers have actually grown in length and bulk. A change in the atmospheric river courses with their increased moisture content has brought greater snowfall to Mt. Shasta.

Five major glaciers remain along with several minor ones. The glaciers are named, in order of their size, Whitney, Hotlum, Bolan, Wintun, and Konwakiton glaciers. The Whitney Glacier, the longest California glacier, was named in 1864 after Josiah Whitney, California's first State geologist. Hotlum Glacier is number two in size on Shasta while Bolam Glacier is third in size. Wintun Glacier is named after the Wintun Indians who migrated south from somewhere in Oregon about 500 AD (these folks introduced the bow and arrow to central California). Konwakiton Glacier, a Wintun Indian name for "The Muddy One" is actually the largest glacier remaining on Shasta.

An event of interest to cavers occurred in August of 1924. Within several (all?) of these glaciers are lengthy glacières, ice caves, cut out of the glacial ice itself by melting water and air currents. These caves are not stable over long periods of time. On the morning of August 4th, hikers reported that a rush of muddy water roared down Muddy Creek, continuing for two days before stopping. At about noon of August 6th, other campers felt the ground tremble underfoot that was accompanied by an extremely loud roaring sound and they leapt for their lives as a huge wall of water, boulders, ice blocks and mud cascaded down the creek, destroying their camp.

Whitney Falls Trail

Mt. Shasta is a majestic, steep-sided stratovolcano located about 60 miles north of Redding along the I-5 corridor in Northern California. It is the most voluminous of all the Cascade Range volcanoes, and the towns of Weed, Mt Shasta City, and McCloud lie in its shadow. Photo by Carol Highsmith, Library of Congress.

Apparently the roofs and walls of glacierés (ice caves) within the lower half of the Konwakiton and adjacent Stuhl Glaciers failed, sending a wall of icy water, boulders, mud, and "chunks of ice as big as a house" roaring down Mud Creek Canyon. When the water subsided and everyone stopped ogling the formerly frozen carcass of a pronghorn antelope melting out of a flood-carried ice block, it was determined that the formerly enclosed ice cave passages had collapsed.

It was estimated that nearly a quarter mile long section of cave and its enclosing glacial ice had been destroyed in a most spectacular manner. The weeks leading up to September 6th saw more glacial collapse and large floods, but not as spectacular as the initial jokulhlaup event. Evidence of another larger suspected jokulhlaup was noted by civil engineer, H. B. Reem of Mt. Shasta City. In 1879, he found sand and debris deposits in greater quantity than the 1924 debris fields. These had apparently made a lengthy run down the southeast side of Mt. Shasta almost reaching the town of McCloud. This may have been the prodigy of yet another glacier/glacieré collapse - perhaps either the Wintun or Konwakiton-Stuhl Glaciers - but it was too degraded to tell for sure.

There have been reports of other caves on Mt. Shasta. The most reliable reports mention a series of firn or melt caves and grottos in the ice fields near the summit warm springs - a situation similar to the firn caves atop Mt. Rainier in Washington State. There, steam and sulfurous gas have melted out a limited series of passages that are still unmapped.