, 1876-06-10

L "
Number and Mature Of the Living GIa'
ciers Of California; History OF
Glacial investigation
John Muir the well known gcoogist,
delivered an interesting lecture in Dash
,way Hall. last evening, upon "Thc
Glaciers Of California" previous to start.
mg for his usual summer work in study
~ this wonderful feature OF our STATE.
He opened the lecture by SAYING that the
-acal epoch, in which the beautiful ana
sublime scenery Ol the mountains was
ormcd, existed at comparatively re-
cent period, and that the Sierra is no"
a sculpture, MS it were, just un-
ycilcd to view and fresh from the lmnd
If the Great Artist. The formation Of
glaciers was then explained, The vapor
from the sea rising and passing land
ward through the atmosphere, Is con
dcnsed in the form Of snow by the cold
air about the mountains, and 10y alter
nate thawing and freezing is finally solid
fled to ice and begins flowing down the
mountain again to the sea. When the
.lacier--which was defined as Il current
ci' ice formed from snow, reaches the
warmer regions Of the plains, the ice be-
comes water and flows away in rivers
until it again minglcs with the sea from
whence il came. Glaciers are usually
formed of several tributaries, AS river
is formed from several streams, and upon
lis surface it carries huge weights OF rock
and debris, MS drllt.wood is borne along
upon the breast of the broad MiSsis-
sippi.
MORAINEs.
Its course down the mountains is
marked by masses of sand and rocks,
which are forced by its motion to the
sides. and forms what are termed in geo.
logical parlance, Lateral mOraines,' " and
where it melts in the plain it deposits
, the debris which it carried from the
mountains, and forms a " terminal mo-
saine' When two glacial currents meet,
the Garth and rocks upon their inner
surfaces as they join are forced together,
and upon the broader glacier which they
form, being carried down the center OF
the stream and forming "medial NOR
sine." If formed of three branches the
glacier shows two lines of medal NOR
iincs; if of three, four and so on, the
number of moraines always being one
less than the number of tributary
streams. The glacial stream, like that
of river, is not Of equal width at all
points, but in some places it is pinchcd
in narrow gorges and in others it cx-
pands into widening canons. Lying be-
tween masses of solid rock, as it often
does, it seems as if no power the glacier
might possess could move it but it does
move, steadily and unbroken in its flow,
rs if mighty river.
THE MOVEMENT OF GLACIERs-EARLY
EXPERIMENTS.
Only fifty years have elapsed since this
movement Of glaciers was first shown in
the Alps Of Switzerland, by Professor
who built himself hut of stone in
the centre Of the glacier of the Aar, and
who found that, in three years, it had
moved $50 feet toward the valleys.
Fourteen years after, Professor Agassiz
visited the place and found that the hut
had moved about 1900 teet in that time,
and, continuing the experiment, he
drilled ten holes, each six feet deep at
equal distance across the glacier, and in
serted in them iron bars, assuring him
self that they were in perfect line by the
use of theodolitc. He had supposed
that the sides would move fastest, owing
to the melting of the ice by the reflec-
tion of the sun upon the rocks but, re.
turning in year, he found the reverse
was true, and that his stakes now formed
semi-circle, with the convex side down
stream. The average speed of Swiss
glaciers is eight inches in twentyiour
hours, though no two flow with the same
velocity, and, owing to the melting of
the ice, the current is more rapid in sum-
mer than in winter.
VELOCITY OF CALIFORNIA GLACIERS.
The only California glacier whose
speed had beea measured by the lecturer
was the one on Mt. Mcclure. In 1871
nc plEnted f;r stakes across it, and in