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Glacial History

Existing Glaciers

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The USGS Provisional 1986 topo map of Mount Shasta recognizes seven glaciers although Rhodes (1987) suggests there are ten extant glaciers. The seven glaciers recognized by the USGS are Whitney Glacier, Bolam Glacier, Hotlum Glacier, Wintun Glacier, Watkins Glacier, Konwakiton Glacier, and Mud Creek Glacier. The other glaciers are Upper Wintun Glacier, Chicago Glacier, and Olberman Glacier (Rhodes, 1987; Biles, 1989).

Glaciers on Mount Shasta were not described in the scientific literature until Clarence King published his observations of an 1870 expedition on Mount Shasta in the American Journal of Science in 1871. The first glacier King and his companions saw was Whitney Glacier, named after Josiah Dwight Whitney. King stated, "Its entire length in view was not less than 3 miles, its width opposite our station [on the rim of Shastina] about 4,000 feet..." (King in Russell, 1885). The next day they climbed the main peak and saw three more glaciers, "the largest about 4 1/2 miles in length and 2 or 3 miles wide." King pointed out that there were also relics of glaciers on the mountain.

J. D. Whitney and William Brewer of the Whitney Survey explored the mountain in 1862, prior to King's expedition (Russell, 1885; Farquhar, 1923; Hill, 1975; Biles, 1989). Not only did they not see any glaciers, Brewer stated in an 1862 letter to George Brush, "In this climate, although immense quantities of snow fall in winter, no rain falls during the long cloudless days of summer, so there are no glaciers." The letter describes how difficult the climb was; Whitney had "his fingers frostbitten" and much of the day was cloudy.

Although not published in the scientific literature, glaciers on Mount Shasta were known about as early as 1866, prior to the scientific explorations. Following is an excerpt from an 1866 article in the Yreka Journal:

Crater and Summit of Mount Shasta -- A New Route

In 1882 Gilbert Thompson conducted a topographical survey (see map). They observed five major "ice streams" and pointed out that a "careful examination of some of the ice-bodies on the western flank of Mount Shasta would perhaps lead to their being classed as glaciers of secondary magnitude..." (Thompson in Russell, 1885). Thompson made an interesting statement that photos from 1870 showed there was more snow than when he made the climb in 1882.

Joseph Silas Diller worked in place of C. E. Dutton for a 1883-84 USGS survey of Mount Shasta. He made several later publications relating to Mount Shasta, among them Mount Shasta, A Typical Volcano (1895). In this monograph, he discusses five glaciers of Mount Shasta, Whitney, Bulam [sic], Hotlum, Wintun, and McCloud [Konwakiton].

Photography by J. S. Diller, circa 1883.  Image courtesy of World Data Center A for Glaciology
Whitney Glacier
(Misery Hill in background, flank of Shastina to right)
J. S. Diller, circa 1883

Whitney Glacier

Whitney Glacier, named after the geologist Josiah Dwight Whitney, is the longest glacier in California (Rhodes, 1987; Biles, 1989) and the one which most resembles glaciers in the Alps (Thompson, 1882; Diller, 1895), being the only true valley glacier on Mount Shasta. Whitney Glacier flows from just below the peak of Mount Shasta in a northwesterly direction through the valley between Mount Shasta and Shastina. Whitney Glacier has the thickest ice measured on a Mount Shasta glacier at 126 feet (Driedger and Kennard, 1986). Looking at an aerial photo of the north side of Mount Shasta, one can see there are two major sources for this glacier. Just to the west of Shasta's peak is the Whitney Glacier BERGSCHRUND. The ice flows down from here, crossing an ARÊTE and joining with a secondary glacier situated on the north side of Shastina COL. Once the two sections join together, the glacier cascades down the mountain in an icefall.

Air photo of Whitney and Bolam Glaciers
Whitney and Bolam Glaciers
Air photo by Linda Freeman, October 17, 1998

Bolam Glacier

Bolam Glacier is located on the north slope of Mount Shasta. The meltwater drains into Bolam Creek, which joins with Whitney Creek and Graham Creek to form the Whitney-Bolam debris fan (Osterkamp, Hupp, and Blodgett, 1986). This region is subject to mudflows and will be described further in the next section.

Hotlum Glacier

Hotlum Glacier is the largest glacier on Mount Shasta in area and volume, at 19.4 million square feet and 1.3 billion cubic feet respectively (Driedger and Kennard, 1986). Hotlum Glacier is the only glacier in California with a medial moraine (Diller, 1895; Rhodes, 1987). Diller (1895) further defines it as, "...deeply crevassed, exposing the green ice... to depths of 100 feet." The terminal MORAINE of this glacier is a mile wide (Diller, 1895).

Photo of Meltwater from Hotlum Glacier by Bill Hirt
Meltwater from Hotlum Glacier
Photo by Bill Hirt

While Hotlum Glacier is not famous for its mud flows, a July 12, 1928 article in the Mount Shasta Herald questioned whether Hotlum Glacier might not produce an avalanche that year. Stuhl, on returning from one of his expeditions, stated that the "old military road, over which General Canby traveled, is now impassable on account of the flow from Inconstance Creek." This creek flows from Hotlum Glacier and was "out of its banks;" while it had overflowed in past years, it never had this early according to local knowledge. The article further states that Ash Creek has muddy water each year but leaves no deposits and Mud Creek has always "been the creek to leave its bank and cause so much trouble."

Wintun Glacier

Air photo of Wintun Glacier
Wintun Glacier
Air photo by Linda Freeman, October 17, 1998

Wintun Glacier is on the southeast side of Mount Shasta. Rhodes (1987) believes this glacier should be divided into 2 glaciers, Wintun Glacier and Upper Wintun Glacier, but this is not recognized by the USGS. The meltwater of Wintun Glacier flows into Ash Creek. Unlike most of the other streams on Mount Shasta, Ash Creek flows most of the year (Osterkamp, Hupp, and Blodgett, 1986). Wintun Glacier does not have a terminal moraine as mud flows from Ash Creek have formed, along with mud flows from Mud Creek, the 300 km2 Mud-Ash debris fan north of the McCloud River (Diller, 1895; Osterkamp, Hupp, and Blodgett, 1986).

Watkins Glacier

Air photo of Watkins Glacier taken October 17, 1998Watkins Glacier, also known as Clear Creek Glacier as it is upslope from the springs which feed Clear Creek (a tributary of Mud Creek), is one of the glaciers of Mount Shasta recently recognized by the USGS. It formed during the Little Ice Age and is located on the southeast side of the mountain (Rhodes, 1987). There is a "well preserved Mathes moraine" on Watkins Glacier (Rhodes, 1986).

Watkins Glacier is named after R. Harry Watkins, Jr., a late Siskiyou County resident who tried to have this glacier recognized for much of his lifetime. It is speculated in an issue of the Mount Shasta Herald (Heston, 1978) that even though this cirque glacier was depicted on a 1883 USGS sketch, it was not recognized as a true glacier due to the name of the creek below its base. Streams flowing from glaciers have rock flour in them, resulting in a milky appearance; the name Clear Creek suggests otherwise. In the same article, Watkins is quoted as saying, "I'm the champion of this little tiny glacier. That's what I'm interested in -- to get people to recognize it." The letter granting him this long sought-after recognition follows:

Konwakiton Glacier

Konwakiton, which means "muddy" in the Wintu language, has also been called McCloud Glacier (Diller, 1895). This glacier used to be much larger (Diller, 1895; Biles, 1989) and rocks with striations can be found here. The meltwater from Konwakiton flows over a waterfall into Mud Creek, which is located in a V-shaped, ash-layered canyon. Konwakiton Glacier was the source for many of the mudflows during the 20th century.

USGS photo of Konwakiton Glacier
Konwakiton Glacier
Photograph by United States Geological Survey

Mud Creek Glacier

Mud Creek Glacier is another of the glaciers recently recognized on the USGS 1986 Provisional topographical map of Mount Shasta. It is located directly south of Konwakiton Glacier and to the west of Mud Creek above a 11,267 foot peak just to the east of Sargents Ridge.

Photograph of Peak 11,267 and Mud Creek Glacier from the east by Norm Linn
Peak 11,267 and Mud Creek Glacier from the east
Photo by Norm Linn, July 1955

While not labeled as a glacier on a USGS map until 1986, a 1935 newspaper describes an...

Unnamed Glacier on Mt. Shasta

The disagreement as to the number of glaciers which exist on Mount Shasta can be readily understood if one can envision the entire scenario. Scientific expeditions have been conducted on Mount Shasta since 1870 and have continued to the present. The climate has changed during this time, so that in some years the snowfall would cover any small glaciers that may have been in existence at that time. During times of drought, the smaller glaciers may have receded to the extent that they were no longer recognizable as glaciers, yet in wetter years their regrowth would enable them to again be considered glaciers. When is a receding glacier no longer considered a glacier? Another major point is that maps are typically not revised and reprinted each year, so that it may appear that certain glaciers aren't recognized, when, in fact, they have been.

Although Konwakiton glacier is one of the smaller glaciers on Mount Shasta, it has a large effect on the local population. Mudflows produced from Konwakiton Glacier will be discussed in the next section.

Continue onto Mudflows.

 

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