The sun., 1910-06-12
GREAT ROCK GVALLNCHES
A PERIL or DWELLBRS ON
YOUNG MOUNTAINS.

The san Juan Mountains 0s Colorado
ssem 20 be peculiarly hablo 10 mOnstro,ls
rock and land alidaa. In some instances the
entire faces Of large mountains having
bosn domOllahod. Il Ia tho younger
mountain systsms. ESOlogiOally spsahtng.
Which are most subject 70 these rock
avalanohas. Thus The Hlmalayas. which
rsprosant but infant industries. though
llsty ones. Id the mountain building hne,
have . way Of tumbllng about which would
result IN great cataatropheq were thelr
slOpss and valleys populated 70 any great
oxtsnt
SIR william Conway describes the matter
OF q llttls ahiftlnR Of rock which caused
the formation Of Gonna Laks. In The cen
tral HlmalayAa. The front Of the noun
tain had been undermined by sprinGs until
there was no longer sufficient support.
In the twinkllng Of an eye . large part
Of the mountain slid down and shot acFoas
the valley, dAmming its rivsr with lOtey
and impsrviotm wall. Masses Of rock
were hurled q mile away. blocks Of lime
stone weighing thirty 20 fifty tons being
cant through the air like huge cannon
shots.
Plsnty Of Hlmalayan lAndslidss quite
e. extensive as this have besn recorded
IN the last half century. says the NofsONai
GeograpAie MagnsiAa. while amonG the
remote and unlnhabitsd regions Of the
great ranges numbers more ars Of constant
oCcurFenco.
| ~. to--,.....,,. - A.. an,, T,an Moa,p :
tain landslide area point 20 many such
slides a. these having occurred; but for
tunAtsly this era has ended FOR the noun
talns Of the United States. II b true that
some mOvomsnt is still In progress, and
a. In the Alps and In Alberta mans mining
operations may precipitats disasters.
OTta Of the greatest Of the early Con-
VulsiOns in the San Juan region h known
as- the Silver Mountain slide. IL covers
ten square miles and the amount Of rock
which crashed down the mountain aido
10 beyond conjecture. On the north
western slopes Of Red Mountain about
siK square miles are covered with land
slide d6bris. while many other landalido
areas cover from ono 20 Ave square miles
A singular feature Of the San Juan
country Is the presence Of rock streAms.
veritAbls rivers Of stone which have
flowed down the mountain sides. There
are SCORES Of these rock streams. An
interesting variation IN what IL termed
by Dr.. Gross 'Slumgullion mud 0ow.' >
which damned a fork Of the Gunnison
River and formed Lake San cristobal.
IAndslides are believed 70 bs due gen.
orally 20 moisture. which under favor
able conditions undermines foundations
and causes q breaking away Of overlyinR
rocks. To realize their terrific eject
one must turn 10 such catastrophes a.
the great Elm landslide in Switzerland
In 1881 or the Frank aide in Alberta in 1879
The town Of Elm is the highest village
In the sernf Meadow. OvershadOwing
il ross the steep Plattsnbergkopf. the
outmost buttresa Of q greater mountain
mass About half way up this hill was .
fine slate bed which was mined In q care
lsns manner for school states. A crack
began 20 form above the mine. steadily
widening and splitting the top Of, the hill
Il HErsW 10 he over u feet wdie. swallow
ing up all surface drainage. Every one
seemed 20 have agreed that the mountain
would ultimately fall. but no one thought
the danger imminent. Rocks began to
J fall a. ntervals September n was a
rainy Sunday. Rock masses kept falling
and the mountain groaned and rumbled
People gathered at the foot Of the labortng
rocks 70 watch the falls. Many were
interested. but nuns foreaaw real danger
| ! u.aaa ~ NkN rmaarUanf, tsrwAa,
away from the PlattsnbergkOpt crashed
down over tho slate quarry and spread
out hpon the hat. No one was kilhod BY
this fall. though the rocks re- = o. within
, A saone's throw Of where the 81 'ghtasers
were RRGhorsd. The people Of tho upper
village now became mildly alarmed This
first lall came from the east side Of the
PlattenberHkopf: seventeen minutes later
a second and larger rock mass crashed
downward from the west side.
The gashea made oy the two united
mana isolatSd and unsupported. Then,
four minutes later. a. Il pausinR only 70
catch its breath for the final plunge. thoss
who we're watching the mountain from a
distance beheld the whole upper portion
Of the Phttsnbergk0pf- .0OO. coo cubta
msters Of rOck-suddenly shoot from the
hillside.
A cloud Of dust accompanied il and a
great wind was hung before Il. Trees
were blown about like matches and houses
lifted through the air like feathers and
broken up ~ though little toys by its
force alone. The avalanche. shooting
with incredible swiftness across the val
ley. struck the opposite hill slope obliquely
and was Immediately dedected. like water,
down the level and fertile valley floor.
whose whole width Il covered In a few
seconds 70 the distance % nearly a mile
with mass Of rock debris thirty fest deep.
Most Of the people who had run up onto
the opposite hillside were killed instantly.
Only when the avalanche had struck this
slope and begun to turn aside from Il did
the people in the lower village. far down
along the level plain. have any suspicion
that they wers in danger.
Twenty seconds later all was over, and
the rock torrent had swept away half that
village. The sharp edge Of the avalanche
cut one house in two. All within tho fatal
edge were destroyed. all without we're
J saved.
BEFORE the avalanche there Law a peace.
: ful village and fertile green helds; within
! one minute a solid gray rock carpet had
been aproad bensath which rested the
remains of i50 human beings their houses
and their helda while the familiar Plattan-
bergkopf had vanished aud a great hole
was In its place.
Only slightly lsas dramatic and quits
similar In character 20 the Elm rockalide
was the one which partially swept the
town Of Frank. Alberta. by = hairs I
breadth only did the community escape
complats annihiiatiOn. Thia Aide Waa II
much greater magnitude than the Elm
disaster, although not % many people
, wera kiIlsd.