memex/0_inbox/books/PDM/Bill Mollison - Permaculture A Designer's Manual text/474.txt

slle slopel rhar ran deslray loresl, erop, and
pulldlngs Typleally, avalanehes rul roads, publle
urlllller, and preyenl luel or ard reaehlng rhe .ree lee
olher ealaslruphle phenomena. syalarlehe areas are
ollerl mapped, arld avalanehe warnings lssued when
eprldlllons an be predleled locally. Avalanrhe rhules
are olren dellnealed by pumeer specis spell as aspen

I'M besl delense ls preyenrlon. and lhls rs aehleyed
by a sel ell slralegles 11ng lrorrl preseryallon ol hlgh
slope loresls, lhe plaeemenl pl essenrlal servlees rrl
lunnels, lhe ereealprl pl Vshapeo barrlers lpsplll up lhe
avalanehe lrpnl, arld rhe prevemlon pl selrlemenl ln
hlghnsk areas A new lllreol lollows on rhe dealh pl
sleep slope loresls by and rarrl damage ln general,
upssslope rerraees, walls, and barriers have nol pmzd
eldeerlye, bur snow barrrers an plareaus alpw me slope
ran elleellvely llpld snow above lhe slope and lhelelry
lasren are lpad .

Murh pl lhe dala elven here ls lrorn GM Kuaeva
mm physlral Pruperlres pl 51mm Cowl or lllr arrrrrr
Caarases, USDA p—rnsladarl,

Snow, lllre sand. moves m a rarlery nfmodes‘

- MICROCREEI', under lreere/lhaw and gravity
elleel advanres downslepe a lew eenllmerres per day

. sup pl [hick snow masses (SNOW BOARDS) relay
rover rnelres per day

. SNOW MOUND advanees lrpm rpelly uplands as
a slleamnow n/lerl

- SNOW BODXPS move en masse down shprl slopes

. sNow SLIDES ar velor es pl #5 rn/see oeeur
and ran be arreeled by rerraees

. AVALANCHES pl srlow call rrlerease lrl speed
down long slopes, reaehlng speeds pl up [0 a 5 melres
per seeond my ran be pl preal magnlrude lslll are
usually EPI5OD|C (every 35 years). svsTEMATlc
avalanches am lhpse rhal peeur every year, bul lhese
are unusual. hanger perlpds pl rare heavy snuw lalls
prpduee PERlODXC or rare aralanehes

true are urelul ayalarlehe and rnudsllde lrlovelrlenl
mdlralors and downslope lumlaek pl lower limbs and
underslory, bare "rralns" ldrllererll age classes or
pioneer speelesl sueh as aspen ln downslope srrlps, and
blowndown lpresrs radiating [mm ayalanehe snpuu
all reveal pas: insuolllry valleys, Rock ayalarlehrs
prpduee many ol lhe same em, whleh persrsl lor al
leasl mac years rn eprlllelous mu,

Lllre rhe planl erusls ol lhe deserl or rundra, lhe solar
l—rdlarron erusl prl snow preserves slope srablllry rhls ls
pl mlly a reason-l prpreellon only, and brealrs up ll
reed or shallered by wind, Erghly peroerrl ol all
avalarrehes oeour where old, rompael, or dry snows are
dlslpdged by me rorldensallurl ol molslllre and ram
lrom alr ol more lharl m. hurrlldlry, Many pl me
remalnder are dlslpdged by gusty wrnds, or where
melrwaler lubl-leares lhe rruss rn lhaw perrpds (usually
berweerl mldday and 3 pm. ln llne wealherl, Sudden
lalls ol 504w rm pl snow lollowed by lony perlpds ol
eloull-lree werlller also eause onslalrle snow mmdlllons

Whereas lhe lmpael ol a snow mass rs somewhere
lrprn less lonnes per square rrlerre, dependlng on llle

 

 

450

lolal mass and lhe lord earrled, me compressed arr
blasl lrl rronl pl lhe rrlass ran travel al 33a m/see ms
prpdures 2 severe shoelrwave elleel. Even mowdusl
avalanehes prpduee waves pl lnsmn m/sre and
develop pressures ol :5 almospheres, "laugh rrl knack
down mud bundling:

rammosl
l-errrralrpsl lpermanenlly lroren groundl peellples 47.
507. pl sueh areas as Canada, Russia, and Greenland
l-ealy surlaees. whleh are common over lhe palms
lrosl, ppm prevenl ”lung and rapldly admllepld, lhus
preservlne lhe slablllry ol lrererl areas allher by
elearlrlg, llre, or Dve'rgnllrlg plus lee parlrcle sepur llre
perpeles al we are as hard and abraslye as sandl, rrle
peny layers (in be eroded or removed, Thaw may
raprdly oeeur, so lhal bare sunllen areos pl clayey splls
lmplllsolsl oeeur. and "use lhawed areas ean reaell 1,
l5 ol deep la a lew years he ereslon edeels (plus as.
volume loss pl leel pals be severe end has deslrpyed
many upland yazxng areas lrl Greenland

Morn permallesl ls lpssrl, al llmes lo eon rrl lhlell, so
rhal normal mzlung under pear ls slow, earlh heal lrorn
below reduces lhe lhlrxness pnly abpul I ere per year
In surh harsh areas, solls are lorrneo only as a nsull pl
lrpsl shaflenng ol luck, and bolh sells and “’66 are
filled by lee arllorl and lhaw lgelrllueaerll solar maw
L5 ahlrul 5,000 nrrles more elleellre lharl oarlh hem ll llle
peal ls removed.

Lpess dewsns lwlrldblllvrn sollsl are sum srllea,
20.75% lelspar and low rn leum Lw llelds oldeep
splls lsome deppsrled over loplhlll srrllsl rleellr
lhmughoul Enmpe. Ruslla. coma, and near (Unlmt‘nll‘
glazlm elsewhere They suppprl ex<ellenl lpresrs bul
dry pul qurrldy and have hlgh poreslry hoes deppslls
are slable as sleep walls lo 3m) rrl hlgh. They an
lherelpre muerl used lpr underground housllle ln
chlna, and luv: been perupled lor rlllllerlla

com AREA anlec
when, as ln leeland, lrosl penetnuon lo l2 rrl rn
pasrllns and soil ls a eorrlrrlprl lerrllre, open dllehes al
so m sprang are necessary lo lalre sprlrle lhaw runoll
lrorrl hop, as ule dralrrs are sull [mun rn llle sell urlrll
laler ln sprflng sheep, eallle, and horses are shedded
and hayled lor s morllhs ol she year, grilled m uplands
lor 3 rrloalhs or lrlpre, and an lowland lsprrlellmes
lmprpvedl paslures lpr a monllu, rm heave la areas
ol pareesoll erpslolr needs levelling. resoddrng wllh
peels, or resl lrorn grazing, and bolh a mixcdvlwzshx‘k
erprlomy and Ionglerm rolalloaal grazing may help
lleep worrn parssrres lrlrlrnlrlllll under eonlml Kale,
rape, ryrgnss, barley or rye ran be used as lpdder,
sl a“, or eul lpr wlnler hay Coball and selenlum
delreleneles rn sheep» and ralelum, errpper, and
phosphorus ln pasrure musl be menllpred shrub and
lree browslne ls a laellrr llllle developed, ahhnugh
wlllow. and dwarl blrrh spears areavallableashunvse