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