By C. Frank Brockman
While attention was called to the value of a study of the recession of the glaciers of Mount Rainier by I. C. Russell, of the U. S. Geological Survey (1), in 1897, and Professor J. N. LeConte, of the University of California, in 1907 (2), annual recession tabulations were not undertaken until 1918. In that year F. W. Schmoe, the first park naturalist of Mount Rainier National Park, and Professor Henry C. Landes, of the University of Washington, collaborated in the initiation of such a study on the Nisqually Glacier (3).
That the Nisqually Glacier was receding was noticed by members of the Longmire family (4) about 1885. Accustomed to obtaining ice from the glacier for use in preserving perishable foods, they noticed that they were required to walk farther, each year, to reach the terminus of the Nisqually where the ice was procured. In consequence the position of the Nisqually's terminus became identified with nearby topographical features so that it was possible to locate the place, fairly accurately, in later years.
When recession measurements were begun in 1918, this and other historical records, which were considered authentic, were included in the annual tabulation. Lieut. A. V. Kautz' notations in connection with the snout of the Nisqually in 1857, on the occasion, of the first attempted ascent, aided in the determination of the position of the ice for that year. Consequently recession data, in this instance, go back to the time when the ice of the Nisqually Glacier occupied a position some distance below the present bridge which now spans the Nisqually River.
Glaciers of Mount Rainier for which annual recession records are maintained.
In addition to the Nisqually, recession data are also being recorded annually upon the Emmons, South Tahoma, Carbon, Paradise and Stevens glaciers (5). These six glaciers of varying size and type, which are located upon different sides of Mount Rainier, give a representative picture of the present state of the glaciers of Mount Rainier in general.
The Emmons Glacier (largest in the United States exclusive of Alaska) and the Nisqually are born in the neve field at the summit of Mount Rainier. The Emmons flows in a general northeasterly direction while the Nisqually takes a southern course from the summit. The South Tahoma and Carbon glaciers are both cirque-born, having their origin in glacially carved amphitheaters at about the 10,00 foot elevation. The terminus of the Carbon Glacier is generally recognized as the lowest perpetual ice in the United States (exclusive of Alaska), the present elevation of the terminus of the Carbon Glacier being approximately 3600 feet above sea level. From the base of Willis Wall the Carbon Glacier flows in a general northwesterly direction and, as its lower portion is flanked by high cliffs that prevent ready access of sunlight during the greater part of the day, the recession in this case is generally less than that of the other glaciers. The South Tahoma Glacier flows in a south-westerly direction.
All of the above glaciers, which are of the alpine or valley type, have a definite downward movement. Because of this they are popularly known as. "living" glaciers. The Stevens Glacier, a glacieret or cliff glacier, is almost stagnant. It is therefore known locally as a "dead" glacier. The Paradise Glacier is, in reality, a lobe of the Stevens, and old photos indicate that it has receded considerably since 1912. Like the Stevens, the Paradise is a glacieret or cliff glacier that is largely stagnant.
The results of the recession measurements of all these glaciers are annually transmitted to the Committee on Glaciers of the American Geophysical Union (branch of the National Research Council). That Committee has organized systematic measurements on many other glaciers in the United States and Alaska, and constitutes the central clearing house for information on glaciers in this country. Its reports are published annually in the Transactions of the American Geophysical Union.
Methods used in measuring the recession of glaciers in Mount Rainier National Park.
The determination of the actual end of the ice in the case of practically all of the glaciers on Mount Rainier is a difficult matter. The inclination of the ice at the termini, the presence of ice caves or ice "lips", the varying widths of the termini and their irregular shapes, the character and depth of the morainal material and numerous other factors all contribute to the confusion in determining the actual end of the glaciers in question. In the case of the Emmons and South Tahoma glaciers, the abundance of morainal material makes it particularly difficult to determine the exact extent of the ice.
Because of the difficulties noted above, it was decided that the point in the ice from which the main stream emerged would be arbitrarily considered as the true terminus of each glacier and that this would be adhered to, irrespective of other factors involved, in the recession measurements (6). This method undoubtedly will cause inconsistencies in recession tabulations from time to time, as it has in the case of the Emmons Glacier. It is felt, however that over a period of years the average annual recession figure will be more nearly accurate than if miscellaneous and poorly defined points were selected.
The method by which recession is measured differs with the glacier in question. In the case of the Emmons measurements are made from points on a base line located by instrumental survey. Whenever possible rocks, which have the appearance of permanency, are also marked and check measurements are made from these when possible. Large rocks below the Nisqually, South Tahoma, and Stevens glaciers are marked annually and the recession is tabulated from measurements made from these. In the case of the Carbon Glacier a large rock outcrop, over 700 feet from the terminus, was, after several unsuccessful attempts to locate a permanent marker, selected. This was the nearest permanent point that could be found, but in the fall of 1936 a rock on the moraine below the ice was marked for use in future check data. Three points along the broad front of the Paradise Glacier have been marked and measurements have been made from these each year.
The glacier system of Mount Rainier
This subject is treated in detail in the pamphlet, "Mount Rainier and Its Glaciers", by Dr. F. E. Matthes. However a brief paragraph in this connection will aid the reader of this issue of "Nature Notes" to gain an understanding of the size and scope of this great glacier system.
Mount Rainier is credited with twenty-eight named glaciers aggregating a total ice area of somewhat less than 48 square miles. (See page 144). It is obvious that this ice area is not constant, that it varies slightly from year to year and, as recession data on six of these glaciers indicate, is becoming less in extent each year in common with other glacier systems throughout the world. These recession measurements indicate that the glaciers here are rapidly receding, and there is abundant evidence, in the form of glacially carved U-shaped canyons, moraines, hanging valleys, cirques and glacial tarns, to indicate that the glacier system here was much more extensive than it is today.
Geographic location and climatic factors.
While the existing glacier system on Mount Rainier is but one small remnant of the former extent of the ice in the northwest during that geological period popularly known as the "ice age", it is relatively interesting and important because of the fact that it is the largest of those remnants. In accounting for the present existence of this large glacier system here many factors enter into consideration. Chief among these is the geographic location of Mount Rainier and the climatic factors of the Pacific Northwest.
Mount Rainier National Park lies west of the crest line of the Cascade Range, a portion of which forms a part of the eastern boundary of the park, and which is a north-south climatic boundary in the State of Washington. Thus the geographic position of this area is largely responsible for its climate. The prevailing winds are from the west and are heavily laden with moisture from the Pacific Ocean. As these winds rise in passing over the Cascades. rapid condensation of this moisture is brought about with consequent heavy precipitation, since air cools upon rising and loses its capacity for holding moisture. Topographic features account for local variations in precipitation and, in general, windward slopes receive a greater amount of moisture than do leeward exposures. This accounts for the fact that, although 900 feet higher, the Yakima Park (Sunrise) section of Mount Rainier National Park receives considerably less snowfall than does the Paradise area, for the former is on the leeward side of Mount Rainier.
In general, however, Mount Rainier National Park is characterized by heavy precipitation in common with other areas of like altitude west of the crest of the Cascades. About 75% of the total precipitation each year falls in the period from October to May. Based upon records of the U.S. Weather Bureau the average annual precipitation for Paradise Park (5557') is roughly 100 inches (7). This may be contrasted with the record for Longmire (2760') where the average annual rate is about 78 inches.
Average monthly and annual precipitation (8).
Average monthly and annual snowfall (8).
This great amount of precipitation, the bulk of which falls as snow at the higher elevations (between 9000 and 12000 feet) where most of the glaciers originate, accounts for the existence of the glacier system upon the broad flanks of Mount Rainier. The annual snowfall, transformed into ice by pressure and other means, thus partly offsets the annual melting and, while the glaciers here are receding, this remnant of the "ice age" manages to exist in spite of the inroads of a more temperate climate. The upper slopes of Mount Rainier may be regarded as an artic "island" in a temperate "sea", a fact that accounts for many of the features of interest in this area.
In spite of its latitude, which is comparable to northern Maine, and its excessive snowfall, Mount Rainier National Park is characterized by comparatively mild winters. This is largely due to the proximity of the Pacific Ocean and the prevailing westerly winds. The summers in this region are, in turn, rarely possessed of extended hot periods. The equable climate of Mount Rainier National Park is best demonstrated by temperature records, prepared by the United States Weather Bureau, as follows.
Average Temperature (9).
Highest Temperature (9).
Lowest Temperature (9).
Areas covered by glaciers in the United States
There are nine major areas of glacier ice in the United States (exclusive of Alaska) and a comparison of their relative sizes indicates that the greater percentage exists in the Pacific Northwest. Such a condition is, of course, due to climatic factors of this section that have already been pointed out. These major areas of glacial ice are listed below in their order of importance. (10)
There are, of course, several other areas possessing glaciers, such as the Olympic Mountains of Washington, certain parts of the Cascades not mentioned in the above tabulation, parts of the Sierras in California and parts of the Rocky Mountains in Colorado.
(1) Russell, I. C. Glaciers of Mount Rainier. 18th Annual Report of the U. S. G. S., Part 2; pp. 349-415. 1897.
(2) LeConte, J. N. The Motion of the Nisqually Glacier. Sierra Club Bulletin; Vol. VI, No. 2; pp 108-114. January, 1907.
(3) Two investigations of the movement of the Nisqually Glacier have also been conducted. In July, 1905, Professor J. N. LeConte made such a study and the results were published in the Sierra Club Bulletin as noted above. In 1930-32, the City of Tacoma (Dept. of Public Utilities), U. S. Geological Survey (Water Resources Division), U. S. National Park Service, and U. S. Bureau of Public Roads cooperated in a similar study. While the results of this last study were not published, several typewritten reports, relative to this investigation, were prepared by Mr. Llewellyn Evans. Copies of these reports are included in the library of the park museum, Mount Rainier National Park, Longmire, Washington.
(4) James Longmire discovered the mineral springs near the present village of Longmire, local National Park Service headquarters, in 1883 and took out a mineral claim on the area in that year. For many years the Longmire family operated a small hotel here. (See Brockman, C.F. History of Mount Rainier National Park. Mt. Rainier National Park "Nature Notes", Vol. XV, No. 2; June 1937. pp 66-67).
(5) Recession measurements were made annually on the Nisqually Glacier from 1918-1928 by F. W. Schmoe, thereafter by the writer. Annual measurements on the ether glaciers noted were initiated by the writer.
(6) The Paradise Glacier, because of individual conditions, is an exception to this rule.
(7) This includes the average annual snowfall for this region which is from 50-60 feet, the maximum depth at any one time varying from 15 to 25 feet. On April 2, 1917, a maximum depth of 27 feet and 2 inches was noted, this being the greatest so far recorded. While no official records are available for Yakima Park, casual observations over a period of the past five or six years indicate that the snowfall is considerably less than at Paradise Valley - 10 to 15 feet being the usual maximum depth.
(8) Prepared from U. S. Weather Bureau records. Precipitation data for Longmire from records taken over a 28 year period (1909-1936); for Paradise from records taken over a 19 year period (1918-1936). Snowfall data for Longmire prepared from records taken over a 25 year period (1912-1936); for Paradise from records taken over a 17 year period (1920-1936).
(9) Prepared from U.S. Weather Bureau records. Longmire data computed from records taken over a 24 year period (1913-1936). Paradise data computed from records taken over a 16 year period (1921-1936).
(10) This tabulation was prepared by the U.S. Geological Survey in answer to a request from this park in September, 1935. Concerning this tabulation Mr. G. F. Loughlin, Chief Geologist, U.S.G.S., states -
"Mr. W. C. Alden. . . .reports the following concerning the approximate areas of existing glaciers on Mt. Rainier and other peaks in Washington, Mt. Hood, Oregon, Mt. Shasta, Calif., the mountains of Glacier Nat'l Park, Mont., and the Wind River Mountains, Wyo., these being the largest areas of glacier ice in the United States, not including Alaska. These estimates were made by Mr. Alden by tracing and fitting together composites of the several individual glaciers in each of the mountain groups, as shown on the following topographic maps, and are, of course, only approximately correct."
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