[Clinton L.] Merriam
To Clinton L. Merriam
Yosemite Valley September 24th 1871
The main trunk glaciers which entered Yosemite by the Tenaya, and Nevada, and South Canons, have been known to many since the publication of the first volume of the California State Geological Survey; but I am not aware of the existence of any published account of the smaller glaciers, which entered the valley by the lower side canons, or indeed that their former existence was known at all.
I have been haunting the rocks of this region for a long time, anxious to spell out some of the great mountain truths which I felt were written here, and ever since the number, and magnitude, and significance of these Yosemite glaciers began to appear, I became eager for knowledge concerning them and am now devoting all my time to their history.
You know my views concerning the formation of Yosemite, that the great valley itself, together with all of its various domes and sculptured walls, were produced and fashioned by the united labors of the grand combination of glaciers which flowed over and through it, their forces having been rigidly governed and directed by the peculiar physical structure of the granite of which this region is made, and moreover, that all of the rocks and lakes, and meadows of the whole upper Merced basin owe their specific forms and carving to this same glacial agency,-- -- -- --
I left the Valley two weeks ago to explore the main trunk glacier of Yosemite Creek basin, together with its radiating border of tributaries, gathering what data I could
read regarding their age, and direction, size, etc., also the kind and amount of work which they had done, but while I was seeking for traces of the western shore of the main stream upon the El Capitan ridge, I discovered that the Yosemite glacier was not the lowest ice stream which flowed to the valley, but that the Ribbon basin or Virgins Tears as it is also called, was also the bed of an ancient glacier which flowed nearly south, uniting with the central glaciers of the summits, in the valley below El Capitan.
This Ribbon glacier must have been one of the very smallest of the ice streams which flowed to Yosemite, having been only about four miles in length by three in width. It had some small groove tributaries from the slopes of El Capitan but most of its ice was derived from a high spur of the Hoffman group to the north, which runs nearly southwest. Its bed is steep and regular, and it must have flowed with considerable velocity. --
I could not find any of the original grooved and polished surfaces of the old bed, but some protected patches may still exist where a boulder of the proper form has settled upon a rounded summit. I found many such preserved patches in the basin of Yosemite creek, one of which is within half a mile of the top of the falls. It has a polished surface of about four square feet, with very distinct striae and grooves, although the unsheltered rock about is is eroded to the depth of four or five inches.-------
Inasmuch as this small glacier sloped openly to the sun, and was not very deep, it was one of the first to die,
and of course its written pages have been longer exposed to blurring rains and frosts, but notwithstanding the many crumbling blotting storms which have fallen upon the lithographs of this small ice-stream, the great truth of its former existence in this home, written in characters of moraine, and meadow, and fluted slope, is just as clear as when all of its shining new-born rocks gleamed forth the fall shadowless poetry of its whole life.
There are a few castle-shaped piles, and crumbling domes upon its east bank, excepting which the basin is now plain and lake-like. But it contains most lovely meadows, interesting in their present flora, and in their glacial history, and noble forests made up mostly of the two silver firs (Picea amabilis and P. grandis) planted upon moraines which have been spread and leveled by the agency of water. --
These rambling researches in the Ribbon basin recalled some observations made by me a year ago in the lower portion of the can~ons of the Cascade and Tamarack streams, and I now guessed that careful search would discover abundant glacial manuscript in those basins also. Accordingly on reaching the highest point on the rim of the Ribbon ice, I obtained broad map views of both the Cascade and Tamarack basins, and singled out from their countless adornments, many forms of lake, and rock, which seemed to be genuine glacier workmanship, unmarred in any way by the various powers which have come upon them since they were abandoned by their parent ice.
This highest ridge of the Ribbon glacier basin, bounded its ice on the north, and upon its opposite side I saw shining
patches, which I ran down to examine. They proved to be polished unchanged fragments of the bottom of another ancient ice stream, which according to the testimony of their striae, had flowed south 40° west. This new glacier proved to be the eastmost tributary of the Cascade. Anxious to know it better, I proceeded west along the Mono trail to Cascade meadows, then turning to the right, entered the mouth of the tributary at the upper end of the meadows. Both of the ridges which formed the banks of the stream are torn and precipitous, evidently the work of ice. I followed up the bed of the tributary to its source, upon the flat West bank of the Yosemite basin, and throughout its whole length there is abundance of polished tablets, and moraines, and various kinds of rock sculpture, forming ice testimony as full and indisputable as can be rendered by the most recent glacier path-ways of the Alps.
I should gladly have welcomed the grateful toil of exploring the main trunk of this Cascade glacier from its farthest snows upon the Tuolumne divide, to its mouth in the Merced Can~on below Yosemite, but my stock of provisions was too small, and besides I felt that I would most likely have to explore the basin of Tamarack also, and following westward among the older, changed and covered glacier highways, I might drift as far as the end of Pilot Peak ridge. Therefore turning reluctantly to the easier pages of Yosemite creek I resolved to leave those lower chapters for future lessons. --- --- But before proceeding with Yosemite Creek let me distinctly give here as my opinion that future investigation will discover proofs of the existence in the earlier ages of a Sierra Nevada ice of vast glaciers which
flowed to the very foot of the range.
Already it is clear that all of the upper basins were filled with ice, so deep and universal that but few of the ridges were sufficiently high to separate it into individual glaciers. Vast mountains were flowed over, and rounded or moved away like boulders in a river.
Ice flowed into Yosemite by every one of its canons, and at a comparatively recent period of its history, its north wall, with perhaps the single exception of the crest of Eagle Cliff, was covered with an unbroken stream of ice, the several glaciers having united before coming to the wall. -- --
1871 Sep 24
Original letter dimensions: 26.5 x 20.5 cm.
Muir, John, "Letter from John Muir to [Clinton L.] Merriam, 1871 Sep 24." (1871). John Muir Correspondence (PDFs). 1397.
Reel 02, Image 0541
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