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Black Rapids Glacier, Alaska



Black Rapids Glacier, Alaska
Advance of 25 Feet is Made in Movement in One Day, Measurements Show

By OTTO WM. GEIST

    Receding and dying glaciers not news in geologic annals. But when a glacier evidences signs of wanderlust and when homes and rivers that can flood a large valley are in its path, that is news.

    Colonel H. E. Revell, who with his family operates Rapids Roadhouse on the Richardson Highway 138 miles from Fairbanks, discovered one morning last December that the glacier which ordinarily was visible only on a clear day and then as a narrow, white line in the far distance, now stretched across the floor of the little valley like a bulwark. Whether this change had been taking place so slowly as to be almost imperceptible or whether the glacier had started on a toboggan-like slide, the Revells were unable to decide. But the fact remained that the glacier had moved not only feet but miles, was still moving, and showed no intention of stopping.

Trip by Airplane

    In February I made a trip by airplane with Jack Herman to photograph the face of the glacier and make a preliminary study of its advance. Early in April, four of us, outfitted with heavy survey instruments as well as barometers, cameras, thermometers, bedding, food, and a tent, were landed by plane on the glare ice of the river two miles above the face of the glacier. The next day Harry Revell brought our equipment to the foot of the glacier with his dogs and we pitche dour tent less than 300 feet from the face of the glacier.

    The vast river of ice that stretched for a mile and a half across the valley, twenty-five mile sor more back, and 400 to 500 feet high, seemed to be a living, sinister mass. It rumbled and crashed and shook the earth until we could easily imagine we were in front line trenches. Even the dogs barked at it.

Purpose of Trip

    The purpose of our trip was to map the region into which the glacier might advance, to measure accurately the rate of flow, and to photograph systematically the glacier and its surroundings.

    The advance of the ice was easily measured. At regular intervals, lines of stakes were set perpendicular to the moving face and daily the distance between the stakes and the edge of the ice was measured with steel tapes. While we were there, the glacier's advance was a little over 25 feet per day. Since it began to move nearly a year ago, it has covered a distance of approximately four miles.

    Undoubtedly there are many "flowing" glaciers on the earth's surface but it is very seldom that such an active mass is so close to civilization, to be studied and recorded.

Bears Out Natives' Stories

    The morains and other glacial deposits in the Big Delta district bear out the stories of natives, handed down to them, of days when the Black Rapids glacier was on the opposite side of the river, miles from its last year's location. So surely this is not the first journey taken by this restless mass of ice.

    The pertinent question now is - whether the force of the glacier has been spent or whether there is still danger of it crossing the river and destroying the Revell home or changing the course of the river and causing a flood which would easily wash out long stretches of the Richardson highway.

Cause of Movement

    The cause of such a glacial movement is the enormous accumulation of ice and snow in the catchment basin. When this load becomes heavy enough and is excited by an earthquake or other unusual disturbance, the whole mass automatically begins to move. The pressure of billions of tons of ice and snow somehow must be released and so the inexorable march begins.

    In the last few months, the movement of the glacier has slowed down to less than 19 fete per day and indications point toward the probabiliity that its chief force has been spent and it can not cover the several hundred feet to the river before spring.

Would Prevent Jamming

    It would then be moving so slowly that the swift, high waters of the Big Delta would eat out its face fast enough to prevent a jamming of the river. If it would cover the frozen surface of the river this winter, undoubtedly aserious flood condition would prevail at breakup time, but at the present rate of movement, this will not occur.

    If all of Alaska's glaciers had the itinerant characteristics of the Black Rapids glacier, certain sections of the Territory wouldn't be a very safe place for human habitation but fortunately most of them are content with slow recession or occasional sluffing and cause no worry to nearby residents.




Related Links

Black Rapids Glacier - information with photos and maps, from the U.S. Geological Survey.

Rapids Roadhouse - a brief history with photos, from The Lodge at Black Rapids.

Richardson Highway - historic and current information about the highway, from ExploreNorth.



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