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Glacial HistoryMudflows |
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Glacial HistoryMudflows |
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In the summertime, especially in the late afternoon, the glaciers on Mount Shasta send meltwater down the stream channels at their bases. Much of the water is quickly absorbed by the volcanic substrate. However, if it has been especially warm for a continued period, or a summer thunderstorm adds to the meltwater, mudflows can form.
MUDFLOWS, also called debris flows or JÖKULHLAUPS (especially when volcanic activity warms things up), carry a cement-like mixture of volcanic ash and water combined with larger material, including boulders. The Whitney and Bolam glaciers on the northwest side of Mount Shasta and the Konwakiton glacier on the south side of Mount Shasta are the the glaciers notorious for producing mudflows. However, the Hotlum and Wintun glaciers have also produced numerous mudflows over the past several hundred years (Miller, 1980).
During the past one hundred years, there have been nine known mudflows from the Whitney-Bolam glaciers, with the most recent one occurring in 1997 (de la Fuente, 1999). Mud Creek has produced at least seven debris flows during the same period. The largest of the debris flows from Mud Creek, which occurred in 1924, 1926, and 1930 will be discussed further.
Konwakiton Glacier is one of the smaller glaciers located on Mount Shasta's southern slope just above Mud Creek. (Mud Creek Glacier curves around Peak 11267 above Shastarama Point.) Konwakiton Glacier has produced several mudflows in historical times (Finch and Anderson, 1928; Hill, 1984; Biles, 1989; Miesse, 1993) as well as during the last 10,000 years (Miller, 1980).
Mud Creek is especially vulnerable to flooding and mud flows because it is on the south side of the mountain and carves through 1,500 feet of ash deposits, which easily erode (Finch and Anderson, 1928). Mud Creek commonly overflows its banks, covering the railroad tracks and highway that run in an east-west direction on the south side of Mount Shasta. The town of McCloud is especially vulnerable to these glacial outburst floods.
For the last few days the Sacramento river in southern Siskiyou has been something like a stream of milk. The water is ashy colored and murky, whereas at this time of the year, when there are no rains up the valley, the water is always as clear as crystal.
Ashes from Mt. Shasta
The discoloration at present is due to the heavy flow of ashes from the
eastern slope of Mt. Shasta down the McCloud and the Pit into the
Sacramento.
Only in McCloud in the Past
In years past it has been common that the McCloud should become milky when
the flow of ashes is started by the melting snows on Mt. Shasta, but the
discoloration has seldom extended farther than Pit river. The milky
McCloud would discolor the Pit for only a very short distance and then the
water of the whole stream would be clear.
First Time for Redding
The "oldest inhabitant" cannot recall ever before having seen the
Sacramento murky at Redding at this time of the year. Redding is at least
20 miles from the mouth of the McCloud and at least 75 miles from the
source of the ashes on the eastern slope of Mt. Shasta.
The 1924 mud flow from Konwakiton Glacier made front page news in the Redding Courier-Free Press six times during the months of August and September. The first article covering the story in this newspaper, on the front page, was:
A veritable river of mud, boulders and ashes extending in width from a few hundred yards to half mile, in some places fifteen to 20 feet deep, is flowing from the mouth of Mud Creek canyon, eight miles above McCloud, on the slope of Mount Shasta, into the McCloud river, says a dispatch to the Sacramento Bee. The sudden flood is attributed by old residents to a sudden break up of the glacier exposed to sun's rays at the top of an extinct volcano. McCloud's water pipes were broken for two days.
The water of the Sacramento river was the muddiest it has been for years...
One of the most interesting articles in the Redding Courier Free-Press was about a carcass found in glacial ice; but beware of accuracy, as the article in the next column is entitled "MARS HAS BIG AREA COVERED BY VEGETATION."
One of the most startling finds that has been made by the many hikers who are now attempting to get to the point where the glacier broke off on the side of Mt. Shasta is the frozen carcass of a mountain sheep, almost perfectly preserved.
A party of ten climbers located the carcass while they were inspecting the huge ice blocks that had broken away from the main part of the glacier.
Carcass 50 Years Old
There are no sheep on Mt. Shasta in these days and none are recalled by
the present dwellers of the mountain region. John Muir recorded seeing a
small band of sheep on the upper reaches of the mountain in 1872 and none
have been observed since that time.
According to this, the specimen discovered in the ice of the glacier must be at least 50 years old, an indication of the great depth to which the sun has penetrated thru the layers of annual snow and ice.
Avalanche Peril Over
McCloud people are confident that what is left of the glacier near the top
is frozen tight to its moorings. There will be no more avalanches, for the
present at least, tho there is no telling what will happen if the weather
should turn warm again.
Hundreds daily visit the "devastated area," which has become an asset as an attraction.
It should be noted here that the "mountain sheep" later proved to be a pronghorn antelope (Hill, 1976). A little over two years later (September 22, 1926), the Mount Shasta Herald had an article about a skull of a plains antelope (Antilocapra americana) recovered from a glacier which was later donated to the Academy of Sciences in Golden Gate Park, according to a October 12, 1926 issue of Courier-Free Press.
News of this flood finally made it into the San Francisco Chronicle on August 19, 1924. Their explanation of events follows:
That a glacier on the eastern slope of Mount Shasta slipped down the mountain side two weeks ago and since has been dissolved by the heat of the sun is the explanation given in McCloud for an unprecedented flow of mud and ashes coming from the north.
The mud flow starts four miles north of McCloud and three miles below the intake of the McCloud water system. The flow carried away the pipe line and left McCloud without water over Tuesday and Wednesday. For two days a supply was hauled in by train. Until today the mud and ashes came down the valley in amounts four or five times as great as known before.
Today the weather turned colder and the water and mud is diminishing. Mud has made the county road from McCloud to Bartle impassable, six miles from the source of the flow.
It is considered certain that the four-inch rise in the Sacramento river here last week was caused by the melting glacier.
Another article appeared in the San Francisco Chronicle the following day, nestled between "Narcotics found in Hair of Suspect" and "Two Plans Given in L.A. Phone Problem" in the August 20, 1924 edition of the newspaper. The article reads as follows:
Excitement over the flood from the melting glacier which threw this district into a panic yesterday was slowly subsiding today, although some fears were felt that another chunk of the glacier might break loose.
The main glacier is located near the peak of St. [sic] Shasta. Observers declared the flood was undoubtedly caused when part of the glacier broke loose from its moorings and slid four miles down the mountain into Mud Canyon.
This particular summer the volume of water was heavier than usual and by August 12th flooding had occurred which "so buried the railroad tracks that traffic was stopped." The area around the RR tracks and highway were covered with material ranging from fine mud to "boulders weighing over a ton" and the material "was over a mile wide in places" (Finch and Anderson, 1928). Mount Shasta received an early snowfall on August 18th. The cold temperatures stopped the flooding temporarily. An eyewitness, J. M. Olberman, reported on August 20th, "The glacier was sloughing off in tons into the creek, great chunks coming down every few minutes with a rumble like that of distant thunder."
The San Francisco Chronicle later reported the following articles in rapid succession:
Mount Shasta's glacier is on a rampage again. The warm weather of the last four days has caused the glacier that slid down the side of Mount Shasta several days ago, to once more send down a torrent of mud and ashes. Mud canyon is today a sort of sluiceway, down which the mushy mud of the texture of concrete pours out onto the flat, sweeping with it boulders as big as a small house.
The situation was so bad Saturday and Sunday that little hope is held for any improvement today.
The mud is now spread over an area eight miles in length and half a mile in width, blocking the McCloud river railroad and preventing the movement of trains yesterday.
McCloud's water supply is still intact, though for a time Saturday night it seemed impossible to keep the water mains in place. Hundreds of motorists from nearby towns visited the area yesterday.
The McCloud river is again more like a river of mud than a sparkling, clear mountain stream. The Sacramento, which cleared up greatly last Wednesday and Thursday, was again as murky today as it was a week ago, the discoloration extending far below Redding, through Red Bluff to Tehama and beyond.
While Mount Shasta continues to spew an unstoppable torrent of mud and bowlders [sic] and icebergs from her glacier-clad peak into the vast mud-sea formed in the valley below, the citizenry of McCloud is waging a fight to save its water supply.
Already the water main has been broken two times in five separate places by the unceasing flow of mud and rocks and repaired, but it appears inevitable the line will be snapped irreparably at any moment.
Railroad Under Mud
The mud river has inundated the McCloud River Railroad, thus cutting off
the possibility of water supply by rail. The break in the rail line has
also cut off communication with the back Siskiyou Country, including the
Pacific Gas and Electric hydroelectric camps with their 1500 men.
Pouring down Mud gulch, a gully which forms a natural sluice for the torrent from the mountain top, the mud comes washing from the melting glacier down into the Mount Shasta national forest. An area a mile wide by twelve miles long has been submerged by the mud, which has hardened.
The flow of glacial mud from Mt. Shasta's melting glacier halted abruptly late today and Mud canyon was almost dry, according to a report from a point four miles north of here. The news was received with some alarm at McCloud, as it is believed the channel has been choked higher up the mountain and that the viscous flood is being damned up only to break loose later with added force.
People in McCloud are waiting patiently for the glacier to exhaust itself. The water supply of the city was repaired again today after the town had been without water for thirty-six hours due to the mains being broken by the mud flow. The McCloud Lumber Company has 150 men at work building levees in an effort to divert the flow from the tracks. The railroad was kept in operation throughout the day.
Reports from Weed are to the effect that a second river of mud has started to flow down the north side of Mt. Shasta past Hoey, a point off the Weed-Klamath branch of the Southern Pacific Railroad, four miles from Weed. During the morning the flow was negligible, but in the afternoon the stream attained a width of fifty yards.
Work on hydro-electric projects of the Pacific Gas and Electric Company on the Pit river, near the scene of the flood, continues uninterrupted, according to a statement by Frank A. Leach Jr., vice-president and general manager of the company. He said that there was six weeks supply of food and plenty of material on hand, and that in an emergency supplies could be brought in over the Redding-Fall River highway.
The mud flow, which has about the texture of pouring concrete, has been practically continuous now for two weeks. The mud-covered flat east of the mountain is now more than a mile wide and from eight to twelve miles long.
News of the mud flow continued. By September 6th it had reached the Stockton Record which reported that "boulders float like feathers on mud stream". Several excellent photos and a nice map appear in this issue. By September 18th, news of the flooding had reached the front page of the San Francsico Chronicle with these bold headlines:
DUNSMUIR, Cal. Sept 18
Approximately fifteen acres of the top southeastern section of the top of Mount Shasta caved in today, causing the collapse of Mud Creek canyon, which has recently been overflowing with mud and rock. The walls of the canyon for a distance of eight miles crumbled with a terrific road [sic], which was immediately followed by a great cloud of dust and volcanic ash that hung over the mountain for several hours.
According to Karl L. Rigor of McCloud, who witnessed the breaking off of the mountain today from different angles, the aura of dust, smoke and ash that hung over Mount Shasta could be seen a distance of twenty miles.
Freezing temperatures at the base of Mount Shasta early today checked the stupendous flow of ashes, mud and lava formation, which poured down the sides of the mountain before a torrent of flood waters, imperilling the lumber town of McCloud, five miles distant.
The walls of Mud Creek canyon, which held the onrush after the weight of the rolling formation caved in fifteen acres on the side of the peak, became more rigid early this morning with the dropping of the thermometer.
Engineers Declare Flood Danger Great
Soon after the rampage of the volcanic formation gained impetus engineers of the United States geologic station went to the scene of the disturbance and pronounced a flood imminent unless the flow was abated.
Preparations were being made tonight to reinforce the temporary reservoir walls which hold the McCloud water supply when the sudden change in weather conditions froze the soft rolling elements, coating the surface with a thin, rigid layer of ice.
Cold Weather Checks Flood of Mud, Water
V. V. Vostmeyer, Forest Service official at the geologic station here, told the Sacramento Union tonight that a sudden change in the temperature is all that held back the rolling torrent from the low-lying valley. He said that if the Mud Creek canyon walls had opened there would have been no way to have halted the progress of the flow.
Vostmeyer declared that he believes the warm weather for the year has ended and from now on the weather will become colder, climaxing in heavy snowstorms along the slopes of the mountains.
Now ice fields above the glacial formations, which were not known to exist on the mountain, are declared to be the cause for the avalanche, Vostmeyer said. These fields are located at about the 10,000 and 11,000-foot levels and have been protected from the rays of the sun by snows which in some sections were from ten to twenty feet in depth.
J. R. Hall, supervisor of the Shasta National Forest, scouts the report that a glacier has slipped from the northern slope of Mount Shasta and is sliding down hill at the rate of five miles an hour [this is in reference to a different glacier, probably Whitney, which was reported from Yreka on September 10th]. Glaciers travel only a foot or two a year, he explains. Even the glacier that has given Mud creek canyon such a deluge did not slip from its moorings. The glacier is still "at home," but the heat of the summer and fall has transformed it into a steaming water pot with the aid of the volcanic ashes which caved away.
I have to wonder what McCloud residents thought about one of the last articles written about the 1924 Mud Creek debris flow when they read the following account printed in the Redding Courier Free-Press:
Mt. Shasta was "all dolled up" Saturday. From one to five inches of new snow caused her to sparkle brilliantly in the cold, clear atmosphere. Colder weather is expected to decisively end the minor disturbances of the week on the slopes of the mountain which have given rise to several reports of large earth movements on the peak. These are held to be principally heavy clouds of dust.
By the end of the summer of 1924, the mud flow deposited 5.4 million cubic meters of mud which covered over 6 square kilometers on the south slope of Mount Shasta near McCloud (Miller, 1980). Untold amounts of mud flowed down the McCloud River and eventually into the Sacramento River, causing the Sacramento River to rise 4 inches early on in the episode according to an August 19th newspaper report from Redding. An interesting notion was presented in a September 25, 1924 article entitled "McCloud Mud Flow to be Fossil Bed" in the Siskiyou News. As the mud flow dries and hardens "...like that of rough concrete ...it is evident from the nature of the deposit that thousands of animals, birds, reptiles, plants and trees caught in the flow will provide the material for a marvelous fossil bed."
In July of 1925 the U.S. Corps of Engineers undertook a study of the mudflow problem. At that time they stated that Konwakiton Glacier was 800 feet wide at its base and 100 feet thick. A waterfall, from the meltwater draining through the many moulins or vertical shafts at the downslope end of transverse fissures, poured forth from beneath the glacier through glacial portals. A west branch of the glacier also had a waterfall pouring forth from it. This study pointed out that future mud flows could not be prevented but that it was possible to divert the flows to the old bed of Elk Creek by constructing a diversion dam which would then divert the flows along a diversion training dike over to Kavinaugh Flats, an old alluvial cone (Hill and Egenhoff, 1976).
Mud Creek On Rampage Runs In Old Channel
Breaks Away From Dam Built Early in Season to Divert It Out Over Kavanaugh Flats Where Mud Was Deposited and Is Sweeping Boulders, Trees and Tons of Muck Down Its Former Course
Mud Creek, the stream flowing from the melting glacier high up the eastern slope of Mt. Shasta, is on a rampage only a little less devastating than the memorable flow of two summers ago.
Creek Breaks Away
The creek broke Monday from its new channel into the old channel and the
mushy mud is once more coursing directly to McCloud river across the flat
between McCloud and Bartle.
Bartle Road Blocked
The wagon road between McCloud and Bartle is blocked. This shuts off
travel to and from Fall River Mills. The blockade will last a month or
more, it is predicted.
$6000 Dam Fails
Early in the season the McCloud Lumber company at an expense of $6000
built a dam at the base of Mt. Shasta which was effective in diverting Mud
creek into a new channel, which conducted the mud flow to Kavanaugh Flat,
where it was spread over a great area and thus kept from pouring in full
volume into McCloud river.
Flows In Old Channel
The creek broke away Monday, tearing its path into the old channel. The
company has fifty men at work today trying to bridle the creek and throw
the torrent back into the new channel. A tractor is on the job and it is
believed the creek can be put back into the new channel.
Water Supply Safe
There is no danger of wrecking McCloud's water supply as was done two
years ago.
Can't Bridge The Creek
The creek between McCloud and Bartle is of course unfordable. A bridge
could be thrown across the creek at small expense today, but there would
be no assurance that the bridge would be in place tomorrow.
Boulders Roll Along
Where the creek crosses the road to Bartle is five miles from the dam.
Thruout this long stretch thick muddy water flows in a torrent, rolling
boulders over and over and sweeping along tree trunks and wooden rubbish.
More Mud Than Ever
McCloud river was never more laden with mud than at present. The creek,
swerving off into its old channel, has carried along with it a good deal
of mud and ashes deposited in the memorable flow of two years ago.
May Bridle Mud Creek
If the company succeeds in throwing the creek back into the new channel,
Redding and other points down the Sacramento river that are now complaining
of the great muddiness of the water will be given relief. The McCloud
railroad is not affected.
Although 1928 was apparently not a notable year, an June 21, 1928 article in the Mount Shasta Herald shows the concern of the public, albeit in a light-hearted manner, in a segment of an article:
There have been about three more mudflows since 1931 (Osterkamp, Hupp, and Blodgett, 1986) as well as the recent debris flow caused by the storms of December 1996 and January 1997. The Mud-Ash debris fan, composed of mudflows from Mud Creek and Ash Creek, is 300 km2 (Osterkamp, Hupp, and Blodgett, 1986).
Governmental aid at various levels were requested over the years to help divert mud flows away from McCloud. Several persuasive arguments were provided in various newspaper clippings between 1924 and 1934. In 1927 the Englebright Bill was put before Congress but failed. Finally, in 1936, a joint-governmental "dedication of Mud Creek Dam Project" was held. An October 8, 1936 article in the Mount Shasta Herald summarized the history of the Mud Creek diversion project.
In 1971 a 3,467 acre region on Mount Shasta's southeast slope was designated as a Research Natural Area by the U.S. Forest Service (Mount Shasta Herald, November 11, 1971). This study site will allow soil scientists, botanists, geologists, and others a chance to study soil and vegetation development on mudflows over time, as there are several dated flows in the area.
Glaciers melting at a fast pace due to recent high temperatures are blamed for Whitney Creek flooding the Mount Shasta Vista subdivision Saturday night.
One home is threatened by the water, which Saturday night cut a new channel for itself right through the subdivision. At least three other homes may be in danger. Buckhorn Road, one of the main roads in the subdivision, now has a three-foot deep channel of water running the width of the road bed.
The water flow has not stopped and according to Dick Ober of Klamath National Forest, will not stop until Whitney Glacier which feeds the creek on Mt. Shasta ceases to melt. "Only cold weather can accomplish that," Ober stated.
The flood caught subdivision residents off guard despite flooding problems in the past. Mount Shasta Vista is located on the flood plain of Whitney Creek. When snow melts on the mountain, the water runs down into the plain, flooding it.
"We didn't think we'd have problems this year because there's no snow on the mountain," stated Bill Lockwook, subdivision president.
However, Ober said the runoff this year is especially heavy as a result of continuous hot weather. "In some places debris from the runoff is in trees at points 15 feet above the ground," he said. "There must have been a huge amount of water coming down."
Ober said the flooding was nature doing its thing. The runoff is full of glacial deposits. "Sometimes it comes down the mountain looking more like Jello than water because of the deposits," he said.
The sediment settles once it reaches the plain where the subdivision is located. Two old channels filled with the muck and forced the creek to find a new channel, thus flooding the subdivision Saturday.
While Ober said KNF wants to leave nature alone, subdivision residents understandably want the water out of their homes. Sherrie Ritchie, whose home is threatened by the flood, tried to keep water off her property Sunday night by shovelling dirt in its path.
"I had to give up because the water knocked the dirt out faster than I could shovel it," she said...
Prior to the 1985 event covered in the newspaper article, there were at least five other mudflows from Whitney Creek during the first half of the 20th century. Since 1985 there have been three more debris flows in this region, with the latest occurring in 1997. The largest mudflow during the 1900s occurred in 1935. This mudflow, like the 1997 one, was triggered by a summer storm. In the case of the 1997 flow, the tropical storm Ignacio brought 4.4 cm of precipitation to Weed on August 19th (de la Fuente, 1999). The 1997 debris flow cut deeply into the deposits left by an earlier mudflow and carried this material downstream.
Satellite imagery from 1999 indicates the extent of the Whitney debris flow. In the following image, the northwest portion of Mount Shasta is located in the lower right section of the image. The center of the image is occupied by lava flows of varying composition and ages, with the Lava Park lava flow shown in bright green. Lake Shastina shows up as bright yellow. The Whitney and Bolam Creek mudflows flow diagonally from the mountain to the northwest. They are blue-violet in color and are located northeast and parallel to the bright green Lava Park lava flow. Notice that the mudlow extends all the way to the agricultural region to the northeast of Lake Shastina. Click on the image for a closer look.
The 1997 Whitney debris flow has been extensively studied by members of the United States Forest Service (de la Fuente et al., 1998; de la Fuente and Bachmann, 1999). They have produced several excellent maps and DEMs as well as made a video documentary. To get a feel for the power of a mudflow, you can watch a segment of the video.
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