trachyte etc with sharp uneven angles forming a crater rim of terrible jaggedness. & protruding in unsubdued roughness through thin slanting beds of ashes & sand that give such exactness of geometrical beauty & symmetry to their general outlines specially if seen at the distance of a few miles
As we proceed still farther northward to the islands of the lake we find marks of still more recent activity in the bright fresh unchanged appearance of the rocks & in the prescence of hot springs, jets of steam etc geysers to south of highest cones also & mud volcanoes The highest of these cones of eruption is said to be 2700 ft above the present level of the lake, but there are terraces upon all the surrounding mtns [mountains] some of which are over [above] 600 ft above the present shore
so that it is certain that all of this volcanic range were [was] like the few north most ones [at present] island cones in the lake Rush Creek exposes in its course through the old lake basin, a deep & very instructive cross section. Showing at the bottom a stratified mass of finely divided volcanic matter, then a stratum of glacier boulders mostly small as found in the moraines of Bloody Canon [Canyon]. Then another stratum volcanic material which is covered with a varying thickness of washed & winddrifted volcanic sand of the same age & quality in every respect as that on [of] the slopes of [upon] the craters & of course derived from them but I think that the lower stratum
[sketch: Thickness 2 ft.]
Original journal dimensions: 10 x 16.5 cm.
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John Muir, journals, drawings, writings, travel, journaling, naturalist