Exploration in the Great Tuolumne Cañon [pp. 139-147]

1873.] THE OllEAT TUOLUffNE CA;Vow~ 145
upon the south sides of trunk cafions deed, after making a few corrections
when they have a direction approaching that are obviously required, for planes of
to east and west. cleavage, differences of hardness, etc.,
The continuity of the north walls of in the rocks concerned, the direction,
such trunk canons is also broken by size, and form of any main canon below
side-canons, but those of the north side a tributary are always resultants of the
are usually much larger, and have a more forces of the glaciers that once occupied
steady and determined direction, being them, and this signifies that glaciers
related to cafions that reach back to high make their own channels. In front of
glacier-fountains; while many of those this great~tributary the cafion ~ about
of the south side may be strictly local. half a mile wide, and nobly gardened
The history of their formation is easily with groves and meadows. The level
read: they were eroded by the action of and luxuriant groves almost always
small, lingering glaciers that dwelt in found at the mouths of large tributaries
the shade of the walls, long years after are very distinct in appearance and histhe exposed sun - beaten north walls tory from the strips and patches of forwere dry and bare. These little south- est that adorn the walls of canons. The
side canons are apt to be cut off high soil upon which the fdrmer grow is reabove the bottom of the trunk canon, formed moraine matter, collected, mixbecause the glaciers that made them ed, and spread out in lake-basins by
were swept round, and carried away by streams. The trees are closely grouped
the main trunk glacier, at heights deter- into villages, social and trim; while those
mined by the respective forces of their of the walls are roughish, and scattercurrents. This should always be taken ed like the settlements of the country.
into consideration when we are weigh- Some of these lake - basin groves are
ing the probabilities of being able to breezy from the way the winds are comreach the bottom of a trunk cafion by pelled to tun~ble and flow, but most are
these tributaries. calm at the bottom of pits of air.
Immediately opposite the point I de- I pushed on down the canon a couple
scended are "royal arches," like those of miles farther, passing over leafy level
of Yosemite, formed by the breaking-up floors, buried in shady greenwood, and
and removal of a portion of a number of over hot sandy flats covered with the
the concentric layers of a dome. All of common ~teris, the sturdiest of ferns,
the so - called "royal arches" of this re- that bears ~~ith patience the hot sun of
gion are produced in the same way. Florida and the heavy snows of the high
About a mile farther down the canon, Sierra. Along the river-bank there are
I came to the mouth of a tributary that abundance of azaleas and brier - roses
enters the trunk canon on the north. Its growing in thickets. In open spots,
glacier must have been of immense size, there is a profusion of golden com~ositce.
for it eroded its channel down to a level Tall grasses brushed my shoulders, and
with the bottom of the main cafion. The yet taller lilies and columbines rung
rocks of both this tributary and of the their bells above my head. Nor was
main canon present traces of all kinds there any lack of familiar birds and flies,
of ice - action - moraines, polished and bees and butterflies. Myriads of sunny
striated surfaces, and rocks of special wings stirred all the air into music.
forms. Just at the point where this large The stellar-jay, garrulous and importributary enters the trunk canon, there tant, flitted from pine to pine; squirrels
is a corresponding increase in size and were gathering nuts; woodpeckers hamchange in direction of the latter. In- mered the dead limbs; water - ousels