John Muir


[John Muir]


[Joseph] Le Conte



Yosemite Dec 17th 71

Dear [Joseph] Le Conte My seasons work is done & I have had one general view of the Merced basin above Yosemite & am astonished at the magnitude of the ancient glaciers with wh it was universally flooded, & of the work wh they accomplished, This entire basin is one glacial monument covered with the earnest eloquent language of Nature gra]illegible]ed in small live characters too[illegible] for our eyes & also in characters of Canon & some wh are difficult to see & read only because of their magnitude. I do not hope to [illegible] [illegible] sentences wh will make an English translation of what I have seen & heard. I only hope to make you come & see for yourself. If you could be made to feel the truth chapters wh are here, you would come at once without looking at times & duties like an attracted atom going to a magnet, strange that manufactured properties & duties should so shackle & cobweb Gods human flies, but next year you will have what you call vacation & then mankind & your wife will let you come, but I will tell you a few baits to make sure of you the Merced ice basin was bounded by the summits & by two spires wh once reached to the summits, viz the Hoffman [drawing with writing: Yo Sem Hoff range summits Obelisk range] & Obelisk ranges, thus - In this basin not one island existed All its highest peaks were washed & overflowed by the ice, Starr King. South Dome & all


some ice from about Mt Lyell Dana etc broke over the Hoffman range into the Tuolumne basin below the Soda Springs thus cutting off the Hoffman from the [illegible] range, & vast ice flows from the Tuolumne above Hetch Hetchy broke over into the Merced basin by the Yosemite & cascade & Tamarac tributaries, & most of this Tuolumne ice had to cross the great canon reaching from near the Soda Springs to Hetchy thus the Tuolumne Canon above Hetch Hetchy is deep as Yosemite [& this deleted] & the fact that so much ice flowed easily over it into the Merced basin gives some idea of the magnitude [drawing, with writting] of the glaciers of this region. It is only the vastness of the glacial pathways of these mtns that prevents one from seeing them at once. The English alphabet would puzzle a professor if written large enough if each letter were made up of many smaller ones. The bed of one unbroken ice river is frequently veiled with forests & a network of tiny water channels. The great central glaciers of Yosemite did not come squeezingly gropingly down to the main valley by the narrow, angular, tortuous canons of Tenaya, Nevada, [illegible]tte, but all of this summit ice was united above the valley, even towards the later glacial period & flowed grandly & directly over all the upper domes like a steady wind, while its lower, bottom currents went mazing &


swedging down among the crooked & dome blocked channels below ---------------------- Glaciers have made every mountain form of this whole basin, & even the summit mountains are only fragments remrants of their first preglacial selves. Every summit wherein are laid the sources -the wombs of glaciers is steeper upon the North than the south side because of the difference in depth & duration between exposed & sheltered glaciers, & this difference in steepness between the N & South sides of summits is greater in the lower summits as those of the Obelisk group. This tells us something of the glacial climate. Such mtns as [illegible] [West?] Starr King Cathedral peak etc do not come under this general law because their cont[illigible] were determined by the ice wh flow- ed above them, but even among these basin mtns we frequently find marked difference of steepness upon their N & S sides because many of these mtns continued to shelter & feed fragmentary glaciers long after the main trunks to wh they belonged were dead, like those of the present day crouching behind Mt Lyell, Red mtn, Black mtn, etc. - steepening all their north sides. The streams of this region were never much larger than they are at present. None of the upper Merced streams give any record of floods greater than the spring floods of today. The bottom portion of this section with perpendicular sides is here about 2 ft in depth & was cut by the water the Nevada here [drawing with writing] never was more than four or five feet deep [writing on drawing as follows:] & all of the bank records of all the upper streams cross section of glacial say the same thing of no season of floods & water basin of Nevada a few miles above Little Yo Sem

glacier stri[illegible] clear & unwashed as low as point [illegible] by arrows, also at the same point there is unmoved glacial boulders


the entire region above Yosemite & as far down as the bottom of Yosemite, has scarcely been touched by any other denudation than that of ice Perhaps all of the post glacial denudation of every kind would not average an inch in depth for the whole region Yosemite & Hetch Hetchy are lake basins filled with sand, & the matter of Moraines washed from the upper canons, the Yosemite ice in escaping from the Yosemite basin was compelled to follow upward a considerable height on both sides of the bottom walls of the valley. The canon below the valley is very crooked & very narrow, & the Yosemite glacier flowed across all of its crooks & high above its walls without paying any compliance to it thus the light-lines show the direction [drawing with writing] of ice current In going up any of the prin- cipal Yosem streams. lakes in all stages of decay are found in great abundance, regularly becoming younger untill we reach the almost countless gems of the summits with scarce an inch of care upon their shallow sandy borders, & with their bottoms still bright with the polish of ice, Upon the Nevada & its branches there is not fewer than a hundred of these glacial lakes from a mile to a hundred yds in diameter with countless glistering pondlets not much larger than moons All of the grand fir forests about the valley are planted upon moraines, & from any of the mtn tops the shape & extent of the neighboring moraines may always be surely determined by the firs growing upon them some pines will grow upon shallow sand & crumbling granite but those luxuriant forests of the silver firs are always upon a generous bed of glacial drift. I discovered a moraine with smooth pebbles upon the shoulder of the South Dome & upon every part of the Yosemite upper & lower walls level enough to hold moraines. I am surprised to find that water has had so little to do with mountain structure here. Whitney says that there is no proof that glaciers ever flowed in this valley yet its walls have not been eroded to the depth of an inch since the ice left it & glacial action is glaringly apparent many miles below John Muir



Date Original

1871 Dec 17


Original letter dimensions unknown.

Resource Identifier


File Identifier

Reel 02, Image 0617

Copyright Statement

The unpublished works of John Muir are copyrighted by the Muir-Hanna Trust. To purchase copies of images and/or obtain permission to publish or exhibit them, see

Owning Institution

The Bancroft Library, University of California at Berkeley. Please contact this institution directly to obtain copies of the images or permission to publish or use them beyond educational purposes.

Copyright Holder

Muir-Hanna Trust

Copyright Date



4 pages



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