Year: 1867

t when all the particles thalI are IN sta
/, of decomposition at the surface haH
e been washed by heavy rains. do n'
4 imagine, then, that yon have witnesse
E the glaciers to advantage when 20
D have walked TO the foot Of them an
{ witnessed the snowy splendor of the
Y surface. In order to have an idea Wha
; the glacier really is, you must see it Ur
: der all possible conditions OF the atmo'
+ phere; and Just as the sky Looks dlflei
} emily under different conditions OF lllu
; mination by The sun, just as the ocea
5 looks differently under different cond
tions Of agitation, just sd does one an
the same glacier look differently. Whe
it has been melting at the surface unde
a hot sun and a succession OF thaWsi
looks like a withered mass OF snow
, looks like q decomp0sed accumulation


Of dirty street snow, after u ma


been melting for some time. GA IN


contrary, let heavy rain fall upon II


and then all its surface becomes nne


the dirt is washed away, and its glowini


colors are brought out; and under thes'


circumstances you should attempt TO SCI


them, If you want to see them to th'


best advantage. There are some phe


nomeDa connected with the transf0rma


ton Of snow into ice, so that glacier


may be formed, which are peculiar, ans
the results Of which cause such changes


upon the ground upon which the giaciel


rests that the presence Of the glacier


may be recognized at all times. / VII
represent two glaciers, in TIVE different


positions, so that I may give you some


idea of what they are. Suppose | make


a section across one Of the valleys 81 hica


are occupied by large glaciers. We


have here liliustrating) the mountain


slope; here, The bottom of the valley


and here the sufaCe nf the glacier
( which occupies that valley and here the
mountain peaks which rise upon the
| sides Of the glacier. I will suppose that
] that valley is 5000 feet above the level ol
{ the sea, and chat the surface Of the gia-
( cier is 500 or 800 feet above the bottom el
/ the valley-that is, the glacier has a
| thickness Of 500 or 800 feet. I will sup
pQse, too, that there are say 20OO feet OF
peaks rising above its surface. Now,
will represent the same glsscier as seen IN
profile, as coming down from the noun
tain into the valley this being the bot
tom Of the valley, slantng from the


summit of tha mountain toward the low


land. [ will represent here the surface


as covered with snow, and gradually
covered with mass Of q more icy char


acter, extending down in this way until


il terminates in this manner continuing


his Illustrations upon the blackboard J


I will also represent the same a.
seen from the surface, so that We


shall have as it were a geograph-


ieal map Of the glacier. Suppose that


I represent here the triangular premoni-


tory of a mountain chain, here another


mountain chain, and here a third noun


tain chain. Here is a valley, and here Is


another valley. This valley is occupied


by q glacier, hardly yet Transformed into


compact ice, but already having lost in a


measure its snowy character. This val


ley is occupied by another such accumu-


latiOn Of snowy ice, which is gradually


passing into the character Of ice. These


two arms of the glacier here meet


together, and form one great glacier
occupying this (third) valley, which is


the result Of the conjunction Of these


two valleys. What will take place here


From all these mountain sides there are


constantly falling blocks Of loose mate


rial, which separate from the wall Of the


mountain in consequence Of the disin-


tegration of the rock; and masses Of
stone Of considerable dimensions may
drop down, sometimes as high as a


house and sometimes Of smaller
NIulEuSlOu5. All THESE uldoecH VIII


be arrested IS they reach the bottom


of the slope Of the accumulated ice.
Suppose I represent here these masses Of
rocks, the results of the disintegration


which is continually going on, as al
mountains are constantly falling to
pieces. In consequence Of this disinte-
grafton, immense masses are rolling
down at all times. We find that the
mass Of loose materials and bOulders
accommodating from any glacier is very
extraordinary. represent here all kinds
of rocks accumulated upon the edge or
the glacier in consequence Of this process
of disin tegration. Where in this profile
view, will these rocks be arrested ?
Here, at the point Of contact between
the ice and the rock. | must say q
word about this before / proceed. I
have represented the glacier as
arched-higher in the middle than
IN the center. You see at once
why this should be SO. The sun
shining against the walls will heat the
walls, and aCthe points Of contact with
the ice, there Is a higher temperature
than at some distance from IL The
natural consequence is tEat where the
glacier abuts against the rock, it is
melted down and is rounded of, while
the center remains permanent. Now,
when masses Of rock full down the
mountain SIope, they are arrested in
these troKs4 between the snow and
the rOckgS and we have generally here
at the iIfhctiOn, between the stone walls
forming the sides of the valleys and the
ice itself, these accumulatiOns of rock
and they ara sometimes so extensive
that they form walls of fifty or one
hundred feet OF more in thickness or
width. Therefore, all along the glacier,
everywhere upon its Sides do We fad
these acCumulatiOns and as these bOUl-
ders are fragments which have broken
away from the mountains, they are ang-
ular. The whole Of these accumulatiOns of
loose materials which fall upon the sur
face of the glaciers are angular boulders.
Now the whole glacier moves, and moves
at a special rate. II moves for various
In the first place because Of the
slope but that is not, as we shall pres
entity see, the principal cause. It moves
in consequence of the freezing of water,
resulting from flowing, and which, while
freezing, expands. You al know that
frozen water occupies more space than
liquid water. If you allow water 10
freeze in a bottle which is cOrked, the
bottle will burst. because ice occupies
more space than water. The amount Of
water which penetrates the ice OF gla-
CieT, and penetrates through it, is not
only that which results from the melt
ing Of the ice; but whenever, instead
of showing, it rains upon the gla-
cier, the rain penetrates into all the holes
and assures in the ice, sinking until it is
arrested by the snow and then, of
course, in the course Of time it will
freeze, and in freezing it viii expand,
and the natural consequence Of eXpan-
sion is motion. The motion must take
pace-in the direction of the least resist
ance-that is, down the valley; and the
natural consequence of al this is that
no glacier is a stationary mass Of ice, but
is an ever moving mass, the rate Of its
motion being propOrtionate TO the bulk
Of the ice. The middle part of the ice,
therefore, which is thicker, moves faster
than the sides, which are thinner and
the middle part, being the most pOrus,
moves faster than the upper part, which
is porus, but allows the water 10 pass
right through, and faster also,
than the lower part, which is more com-
pact, while il admits great quantity OF
water. Here I speak from measure
ments which | have repeated for ten
years, and facts | have had an opportu-
nifty of observing with the utmost
accuracy, ana which were controlled by
surveys which l had made
upon the glaciers of the Alps. So that
there is nothing theoretical in what ! tell
YOU respecting the motions of the gla
ciers in this region. Suppose this to
represent ridges of mountains in the
Bernese Oberland this one representing
the Wetterhorn, and this the kinsteraar-
horn, and ysu have here glacier which
have surveyed for several years
in succession, every boulder upon
the surface of which stood promi-
nently being surveyed and its position
determined with reference 10 the side
Of the valley, so that the change
Of position during one year might be
compared with changes in other years,
aud so that changes might be compared
which Occarred in different parts Of the
day. Thus ! have ascertained and de-
termined the change which the glacier
undergoes during its onward movement


the result, briefly stated being this
that in this region the movement is
about $50 feet in the year, in the center


and the movement down here may be
$50 feet in the center snd the move
ment at the lower end OF the glacier will
he perhaps only 75 feet year in the
center while the movement up here
may not be more than 20Q feet, here not
more than $50 feet, and still higher up
not more than 20 or 80 feet in
year. All this results from the