,illu/ration3 ,eunice ,lake1 nor?we/ ( ,m\nt ,ra9i]4 ,! lake lies 9 a small b$rock bas9 t 0 sc\r$ out by a glaci] betwe5 ab\t #ae1jjj & #bj1jjj ye>s ago4 ,! r\nd$ gre5 slopes at ! f> edge ( ! lake are und]la9 by rock t has be5 smoo!d & groov$ by glaci] ice4 ,?is side ( ,m\nt ,ra9i] rises to ,lib]ty ,cap1 :i* hides ! true summit ( ! volcano4 ,! ,geologic ,/ory ( ,m\nt ,ra9i] ,by ,dwight ,r4 ,cr&ell ,a look at ! geologic pa/ ( "o ( ,am]ica's mo/ sc5ic volcanoes ,,geological ,,survey ,,bullet9 #abib ,,unit$ ,,/ates ,,dep>tm5t ,,( ,,! ,,int]ior ,,walt] ,j4 ,,hickel1 ,secret>y ,,geological ,,survey ,william ,t4 ,pecora1 ,director ,libr>y ( ,congress ,catalog-,c>d ,no4 #gi-fjagjd ,u4,s4 ,,gov]nm5t ,,pr9t+ ,,(fice3 #aifi ,= sale by ! ,sup]9t5d5t ( ,docum5ts1 ,u4,s4 ,gov]nm5t ,pr9t+ ,(fice ,wa%+ton1 ,d4,c4 #bjdjb--,price #fe c5ts 7pap] cov]7 cont5ts ,page ,! *ang+ l&scape ( #ab-fj million ye>s ago #c ,?umbnail biography ( ,m\nt ,ra9i] #aa ,results ( rec5t eruptions #ab ,:y glaci]s8 #bc ,"w habits ( glaci]s #be ,ye/]day's glaci]s #bi ,l&slides & mudfl[s--pa/1 pres5t1 & future #ce ,! volcano's future8 #db ,fur!r read+ 9 geology #dc ,frontispiece4 ,eunice ,lake1 nor?we/ ( ,m\nt ,ra9i]4 ,figure ,page #a4 ,outcrop ( s&/one & %ale 9 ! ,puget ,gr\p #f #b4 ,outcrop ( weld$ tuff 9 ! ,/ev5s ,ridge ,=mation #h #c4 ,granodiorite looks l granite #i #d4 ,geological cross section ( ,m\nt ,ra9i] #aj #e4 ,an old lava fl[ :i* =ms ,ramp>t ,ridge #ac #f4 ,columns ( &esite at ! end ( an old lava fl[ #ac #g4 ,lay]s ( pumice on ! floor ( a cirque #ad #h4 ,g5]aliz$ di/ribution ( "s pumice lay]s #af #i4 ,breadcru/ bomb enclos$ 9 a mudfl[ deposit #ai #aj4 ,pumice lay] ,c1 :i* consi/s ( light-br[n fragm5ts #bj #aa4 ,! rec5t lava cone lies 9 a depression #ba #ab4 ,two ice /reams meet to =m ,c[litz ,glaci] #bc #ac4 ,glaci]-smoo!d & groov$ rock #bf #ad4 ,a lake lies beh9d an end mora9e ( ,flett ,glaci] #bg #ae4 ,recessional mora9es on ! valley floor ( ,fry+pan ,creek #bh #af4 ,ext5t ( glaci]s betwe5 #ae1jjj & #be1jjj ye>s ago #cj #ag4 ,lat]al mora9e at ,rickseck] ,po9t #ca #ah4 ,rock-glaci] deposit at ,! ,palisades #cc #ai4 ,hummocky end mora9e 9 front ( ,emmons ,glaci] #cd #bj4 ,avalan*e deposits 9 ! ,:ite ,riv] valley #cg #ba4 ,! nor!a/ flank ( ,m\nt ,ra9i] #ci ,table #a4 ,*>act]i/ics1 s\rces1 & ages ( pumice lay]s1 ,m\nt ,ra9i] ,national ,p>k #ag #b4 ,summ>y ( important geologic ev5ts 9 ! hi/ory ( ,m\nt ,ra9i] ,national ,p>k #da ,! ,geologic ,/ory ( ,m\nt ,ra9i] ,by ,dwight ,r4 ,cr&ell ,illu/ration3 ,map ( ,cascade ,range ,,wa%+ton ,seattle ,tacoma ,,cascade ,,range ,m\nt ,ra9i] ,m\nt ,adams ,m\nt ,/ ,hel5s ,,oregon ,portl& ,m\nt ,hood ,crat] ,lake ,ice-clad ,m\nt ,ra9i]1 t[]+ ov] ! l&scape ( we/]n ,wa%+ton1 ranks ) ,fuji-yama 9 ,japan1 ,popocatepetl 9 ,mexico1 & ,vesuvius 9 ,italy among ! great volcanoes ( ! _w4 ,at ,m\nt ,ra9i]1 z at o!r inactive volcanoes1 ! ev]-pres5t possibility ( r5ew$ eruptions gives view]s a s5se ( anticipation1 excitem5t1 & appreh5sion n equal$ by mo/ o!r m\nta9s4 ,ev5 s1 _m ( u _c imag9e ! cataclysmic scale ( ! eruptions t 7 responsible = build+ ! giant cone :i* n[ /&s 9 sil5ce4 ,we accept ! volcano z if x _h always be5 !re1 & we appreciate only ! beauty ( its />k expanses ( rock & ice1 its fl[]-/rewn alp9e mead[s1 & its bord]+ ev]gre5 =e/s4 ,m\nt ,ra9i] owes its sc5ic beauty to _m features4 ,! broad cone spreads out on top ( a major m\nta9 range--! ,cascades4 ,! volcano rises ab\t #g1jjj feet above its #g1jjj-;foot f\ndation1 & /&s 9 solit>y spl5dor--! highe/ peak 9 ! entire ,cascade ,range4 ,its rocky ice-mantl$ slopes above timb]l9e contra/ ) ! d5se gre5 =e/s & give ,m\nt ,ra9i] ! appe>ance ( an arctic isl& 9 a temp]ate sea1 an isl& s l>ge t y c see its full size & %ape only f ! air4 ,! m\nta9 is highly photog5ic because ( ! contra/s x (f]s among b>e rock1 sn[fields1 blue sky1 & ! incomp>able fl[] fields t color its l[] slopes4 ,%ad[s ca/ by ! multitude ( cliffs1 ridges1 canyons1 & p9nacles *ange con/antly f sunrise to sunset1 endlessly v>y+ ! texture & mood ( ! m\nta94 ,! face ( ! m\nta9 also v>ies f day to day z its broad sn[fields melt dur+ ! summ]4 ,! melt+ ( ^! froz5 res]voirs makes ,m\nt ,ra9i] a natural res\rce 9 a practical z well z 9 an e/hetic s5se1 = x ensures /eady fl[s ( wat] = hydroelectric p[] 9 ! region1 reg>dless ( season4 ,se5 f ! ,puget ,s\nd c\ntry to ! we/1 ,m\nt ,ra9i] has an unreal quality--its :ite summit1 ne>ly #c miles high1 seems to float among ! cl\ds4 ,we %>e ) ! populace ( ! entire l[l& a ?rill z we wat* skyw>d ! ev5+'s sett+ sun r$d5 ! volcano's we/]n sn[fields4 ,:5 y approa* ! m\nta9 9 its lovely sett+1 y may f9d some?+ t appeals especially to y--! sc5]y1 ! wildlife1 ! glaci]s1 or ! wildfl[]s4 ,or y may feel *all5g$ to climb to ! summit4 ,m\nt ,ra9i] & its neighbor+ m\nta9s h a special allure = a geologi/ because he visualizes ! ev5ts--"s ord9>y1 "s truly spectacul>--t made ! pres5t l&scape4 ,su* is ! fasc9ation ( geology4 ,a geologi/ becomes tra9$ to see 89 8 m9d's eye0 geologic ev5ts ( ?\s&s or ev5 millions ( ye>s ago4 ,&1 mo/ rem>kable1 he c 8see0 ^! ev5ts by /udy+ rocks 9 a cliff or roadcut1 or p]haps by exam9+ e>?y mat]ial t looks l common soil b5ea? pa/urel& _m miles away f ! volcano4 ,our key to und]/&+ ! geology ( ,m\nt ,ra9i] is t ea* geologic ev5t c be recon/ruct$--or imag9$--f ! rocks =m$ at ! "t ( ! ev5t4 ,) ?is pr9ciple z our guide1 we w review ! geologic ance/ry ( ?is maje/ic volcano & le>n :at is beh9d its sc5]y4 ,! ,*ang+ ,l&scape ( #ab-fj ,million ,ye>s ,ago ,! rocks ( ! ,cascade ,range provide a record ( e>? hi/ory t />t$ ne>ly #fj million ye>s ago4 ,ev5 !n1 z today1 waves p\nd$ on bea*es & riv]s ran to ! sea1 mold+ & di/ribut+ mat]ial t =m$ "s ( ! rocks we n[ see 9 ! p>k4 ,y may f9d x difficult to imag9e ! diff]5t l&scape ( t f> di/ant "t4 ,!re 0 no ,m\nt ,ra9i] nor ,cascade m\nta9 range4 ,9 fact1 !re 0 v little dry l& 9 ! area we call we/]n ,wa%+ton4 ,in/ead1 ?is 0 a broad l[l& ( swamps1 deltas1 & inlets t bord]$ ! ,pacific ,ocean4 ,riv]s dra9+ into ?is l[l& f ! ea/ spread s& & clay on ! lu% swamp gr[?4 ,o!r plants grew on ! deposits1 & !y 7 cov]$1 9 turn1 by m s& & clay4 ,9 ?is way1 ?\s&s ( feet ( s& & clay & peat accumulat$ & 7 compact$ into s&/one1 %ale1 & coal4 ,we c see "s ( ! rocks =m$ at t "t 9 cuts along ! ,m[i* ,lake ,road we/ ( ! p>k 7fig4 #a74 ,seams ( coal 7 m9$ at ,c>bonado & ,wilkeson1 #aj miles nor?we/ ( ! p>k1 dur+ ! late #ai? & ! e>ly #bj? c5turies4 ,^! b$s ( s&/one1 %ale1 & coal make up a sequ5ce ( rocks call$ ! ,puget ,gr\p1 :i* is #aj1jjj feet ?ick4 ,wave-ripple m>ks & rema9s ( plants %[ t ! rocks 7 =m$ 9 %all[ wat] fairly close to sea level4 ,h[ c\ld ! rocks h pil$ up to ?is great ?ickness8 ,! coa/al pla9 & adjac5t bas9 mu/ h be5 sl[ly s9k+1 & ! influx ( s& & clay mu/ h j b>ely kept pace ) ! d[nw>d movem5ts4 ,illu/ration3 ,m\nt ,ra9i] ,a little less ?an #dj million ye>s ago1 ! we/]n ,wa%+ton l&scape *ang$ dramatically4 ,geologi/s ,r4 ,s4 ,fiske1 ,c4 ,a4 ,hopson1 & ,a4 ,c4 ,wat]s h discov]$ t volcanoes !n rose on ! =m] coa/al pla9 at ! site ( ,m\nt ,ra9i] ,national ,p>k & became isl&s z ! area sank b5ea? ! sea4 ,:5 molt5 rock 0 erupt$ und]wat] f ! subm]g$ flanks ( ^! volcanoes1 /eam explosions %att]$ ! lava into c\ntless fragm5ts4 ,! result+ debris1 mix$ ) wat]1 fl[$ z mud across great areas ( ! subm]g$ bas9 floor4 ,illu/ration3 ,outcrop ( gray to br[n s&/one & d>k-gray to black coaly %ale 9 ! ,puget ,gr\p along ! ,m[i* ,lake ,road4 7,fig4 #a7 ,y c see rocks =m$ f ^! lay]s ( volcanic mud & s& 9 cuts along ! highway on ! ea/ side ( ,backbone ,ridge & betwe5 ,cayuse ,pass & ,tipsoo ,lake4 ,look !re = alt]nat+ b$s ( grayi%-gre5 s&/one & breccia1 a concretelike rock 9 :i* ! pebbles h %>p corn]s4 ,^! rocks are kn[n z ! ,ohanapeco% ,=mation4 ,l ! ,puget ,gr\p1 ! ,ohanapeco% ,=mation is at lea/ #aj1jjj feet ?ick4 ,yet1 ne>ly all ( x accumulat$ 9 %all[ wat] z we/]n ,wa%+ton cont9u$ to s9k sl[ly dur+ ! volcanic eruptions4 ,! long-cont9u$ s9k+ f9ally end$ aft] ! ,ohanapeco% volcanic activity ceas$4 ,we/]n ,wa%+ton 0 !n lift$ sev]al ?\s& feet above sea level1 & ! ,puget & ,ohanapeco% rocks 7 sl[ly compress$ into a s]ies ( broad %all[ folds4 ,be=e eruptions began aga91 riv]s cut valleys hundr$s ( feet deep1 & wea!r+ ( ! rocks produc$ ?ick r$ clayey soils simil> to ^? t are =m+ 9 "s areas ( high ra9fall & high temp]ature today4 ,look = ! r$ rocks =m$ f ^! old soils 9 roadcuts z y drive along ! ,/ev5s ,canyon road ab\t #b miles s\!a/ ( ,box ,canyon4 ,! next volcanic eruptions1 :i* may h begun betwe5 #be & #cj million ye>s ago1 diff]$ f ^? ( ,ohanapeco% "t4 ,^! volcanoes1 some:]e beyond ! b\nd>ies ( ! p>k1 erupt$ great fl[s ( hot pumice t1 be+ highly mobile1 ru%$ d[n ! flanks ( ! volcanoes & spread ov] _m squ>e miles ( ! adjac5t regions4 ,! pumice fl[s 7 8lubricat$0 by hot volcanic gas emitt$ f inside ea* pumice p>ticle1 :i* buff]$ x f o!r p>ticles4 ,"s hot pumice fl[s 7 #cej feet deep4 ,! heat /ill rema9+ 9 ! pumice aft] x /opp$ fl[+ p>tly melt$ ! p>ticles to =m a h>d rock kn[n z weld$ tuff4 ,repeat$ pumice fl[s buri$ ! hilly l&scape & ev5tually =m$ a va/ volcanic pla94 ,! rocks1 :i* are mo/ly weld$ tuffs1 are n[ ! ,/ev5s ,ridge ,=mation1 :i* y c see along ! highway 9 ,/ev5s ,canyon #a-b miles we/ ( ,box ,canyon4 ,y c recognize ! weld$ tuff by its light-gray to :ite color & its _m flatt5$ & %>p-edg$ inclusions ( d>k] gray pumice 7fig4 #b74 ,ano!r p]iod ( volcanism foll[$1 ( /ill a diff]5t k9d1 :5 lava fl[$ outw>d f broad l[ volcanoes4 ,! fl[s 7 ( two k9ds3 basalt1 ! k9d n[ erupt$ by ,hawaiian volcanoes1 & &esite1 ! type erupt$ by ,m\nt ,ra9i]4 ,individual fl[s #ej-ejj feet ?ick 7 /ack$ on top ( "o ano!r to a total dep? ( fully #b1ejj feet4 ,we "k ^! rocks z ! ,fifes ,peak ,=mation4 ,!y =m _m ( ! cliffs & peaks 9 ! nor?we/]n "p ( ! p>k4 ,y c exam9e !m 9 cuts along ! ,m[i* ,lake ,road betwe5 ,m\nta9 ,mead[s & ,m[i* ,lake4 ,! "t ( ! eruption ( ! ,fifes ,peak lavas may h be5 betwe5 #bj & #cj million ye>s ago4 ,:5 ! ,fifes ,peak volcanoes f9ally became ext9ct1 ?is "p ( we/]n ,wa%+ton *ang$ aga94 ,! rocks once m 7 uplift$ & compress$ into broad folds p>allel to ^? =m$ at ! end ( ,ohanapeco% "t4 ,! rocks buckl$ &1 9 places1 broke & %ift$ ?\s&s ( feet along great fractures1 or faults4 ,illu/ration3 ,outcrop ( light-gray weld$ tuff 9 ! ,/ev5s ,ridge ,=mation along ! road 9 ,/ev5s ,canyon4 ,! angul> d>k-gray fragm5ts 9 ! weld$ tuff are *unks ( pumice4 7,fig4 #b7 ,ab\t #ab million ye>s ago "o or m masses ( molt5 rock1 _m miles across1 pu%$ upw>d ?r\gh ! ,puget ,gr\p & y\ng] rocks4 ,:5 ?is molt5 rock cool$ & h>d5$1 x =m$ granodiorite1 a close relative ( granite4 ,al?\gh mo/ ( ! molt5 rock solidifi$ und]gr\nd1 "s ( x rea*$ ! l& surface & =m$ volcanoes at a few places )9 ! area ( ,m\nt ,ra9i] ,national ,p>k4 ,illu/ration3 ,granodiorite looks l granite & has a light-gray speckl$ appe>ance4 ,! knife is ab\t #c in*es long4 7,fig4 #c7 ,granodiorite is probably ! mo/ attractive rock 9 ! p>k4 ,x is mo/ly :ite1 b x conta9s l>ge d>k m9]al gra9s t give x a 8salt-&-pepp]0 appe>ance 7fig4 #c74 ,! l>ge size ( ! gra9s is a result ( ! molt5 rock cool+ sl[ly at a consid]able dep? bel[ ! l& surface--! individual m9]als _h a long "t to gr[ be=e ! 8melt0 solidifi$ into rock4 ,9 contra/1 ! rocks =m$ f lavas t fl[$ onto ! gr\nd surface are g5]ally f9e gra9$ because ! lavas cool$ too quickly = ! m9]al gra9s to gr[ appreciably4 ,granodiorite und]lies ! ,:ite ,riv] valley1 ! ,c>bon ,riv] valley1 & p>ts ( ! upp] ,nisqually ,riv] valley & ! ,tatoo% ,range4 ,y c see x 9 roadcuts betwe5 ,longmire & ,*ri/9e ,falls & at sev]al places along ! road betwe5 ,:ite ,riv] ,rang] ,/ation & ,:ite ,riv] campgr\nd4 ,illu/ration3 ,geological cross section ( ,m\nt ,ra9i] & its f\ndation rocks f ,"m ,m\nta9 s\?w>d to ,tatoo% ,range4 ,true-scale cross section is ne>ly #ag miles long4 ,slightly modifi$ f ,u4,s4 ,geological ,survey ,pr(essional ,pap] #ddd1 ,plate #a4 7,fig4 #d7 ,aft] ! granodiorite solidifi$1 ! f\ndation ( ,m\nt ,ra9i] 0 complete except = "o o!r l&scape *ange t prec$$ ! bir? ( ! volcano4 ,n long aft] ! granodiorite 0 =m$1 ! ,cascade m\nta9 range began to rise--n rapidly1 b little by little ov] _m ?\s&s ( ye>s4 ,z ! l& rose1 riv]s cut valleys into ! gr[+ m\nta9s s t by ! "t ! new volcano began to erupt1 ! ,cascades _h already be5 c>v$ into a rugg$ range ( high ridges & peaks sep>at$ by deep valleys4 ,deep erosion ?us laid b>e ! rock lay]s 9 :i* we today read ! geologic hi/ory ( ! p>k 7fig4 #d74 ,?umbnail ,biography ( ,m\nt ,ra9i] ,! life span ( a volcano c be comp>$ to t ( an individual--aft] 8 bir? & a brief y\?1 he matures & gr[s old4 ,! bir? date ( ,m\nt ,ra9i] is n kn[n = sure1 b x mu/ h be5 at lea/ sev]al hundr$ ?\s& ye>s ago4 ,we _c tell mu* ab\t ! volcano's complex y\? because mo/ ( its e>lie/ deposits are n[ buri$ "u lat] ones4 ,at an e>ly age1 well be=e ! cone grew to its pres5t size1 ?ick lava1 l hot t>1 fl[$ repeat$ly #e-ae miles d[n ! deep canyons ( ! surr\nd+ m\nta9s4 ,because ^! lava fl[s resi/$ lat] erosion by riv]s & glaci]s1 mo/ ( !m n[ =m ridgetops1 z at ,ramp>t ,ridge1 ,burr\ghs ,m\nta91 ,gr& ,p>k1 & ,klapat*e ,ridge 7figs4 #e & #f74 ,viol5t explosions occasionally ?rew pumice onto ! slopes ( ! gr[+ volcano & ! surr\nd+ m\nta9s4 ,z ! volcano matur$1 ! long ?ick fl[s 7 succe$$ by ?9n] & %ort] ones :i*1 pil$ on top ( "o ano!r1 built ! giant cone t n[ dom9ates ! region4 ,ev5 ?\gh ,m\nt ,ra9i] has gr[n old n[1 x has reviv$ briefly at _m times dur+ ! la/ #aj1jjj ye>s or s & may erupt aga9 9 ! future4 ,! ev5ts ( ! la/ #aj1jjj ye>s1 because !y are s rec5t1 9 t]ms ( geologic "t1 are bett] kn[n ?an ^? ( any e>li] "t1 & we c exam9e ?is "p ( ! volcano's hi/ory 9 "s detail4 ,we w /udy ?ree pr9cipal subjects3 eruptions--because !y h _h widespread effects2 glaci]s--because !y are su* conspicu\s features on ! m\nta92 & l&slides--because !y h dra/ically *ang$ ! volcano's %ape4 ,results ( ,rec5t ,eruptions ,:ile hik+1 y soon become aw>e t !re is a l>ge am\nt ( pumice along ! trails 9 ,m\nt ,ra9i] ,national ,p>k4 ,pumice is a lightweight volcanic rock s full ( air spaces t x w float on wat]4 ,! air spaces1 or bubbles1 orig9at$ :5 fragm5ts ( gas-ri* lava 7 explosively ?r[n into ! air above ! volcano1 & ! molt5 rock h>d5$ be=e ! gas c\ld escape4 ,if y exam9e pumice deposits 9 a trail cut1 9 a /reambank1 or 9 ! roots ( bl[n-ov] trees1 y may also note t !re is m ?an "o lay] 7fig4 #g74 ,if y circle ! volcano on ! ,wond]l& ,trail1 y may notice t ! greate/ numb] ( pumice lay]s are on ! ea/ side ( ! p>k1 b ! ?icke/ s+le lay] is on ! we/ side4 ,! explanation lies p>tly 9 ! s\rce ( ! pumice deposits1 because "s pumice 0 erupt$ n by ,m\nt ,ra9i] b by o!r volcanoes 9 ! ,cascade ,range ( ,wa%+ton & ,oregon & br\ght to ! p>k by /rong s\!rly or s\?we/]ly w9ds4 ,! lay]s ( pumice ?r[n out by ,m\nt ,ra9i] )9 ! la/ #aj1jjj ye>s lie mo/ly on ! ea/ side ( ! volcano4 ,/rong w9ds evid5tly swept eruption cl\ds to ! ea/ dur+ ! outbur/s & prev5t$ ! pumice f fall+ we/ ( ! volcano4 ,?is patt]n ( di/ribution1 c\pl$ ) ! co>s5+ & ?ick5+ ( ! pumice t[>d ! volcano1 reveals t ! lay]s 7 erupt$ by ,m\nt ,ra9i]4 ,illu/ration3 ,an old lava fl[ f ,m\nt ,ra9i] :i* =ms ,ramp>t ,ridge we/ ( ! mead[ at ,longmire4 ,! ?ick lava fl[$ d[n an old valley floor & cool$ & solidifi$4 ,riv]s !n erod$ new valleys along bo? sides ( ! fl[4 ,^! new valleys1 subsequ5tly glaciat$1 are today foll[$ by ! ,nisqually ,riv] & ,kautz ,creek4 ,?us1 ! area ( a =m] valley floor is n[ a ridge4 7,fig4 #e7 ,illu/ration3 ,columns ( d>k-gray &esite at ! ea/ end ( an old lava fl[ f ,m\nt ,ra9i]4 ,?is outcrop is ne> ! po9t at :i* ! highway to ,yakima ,p>k crosses ,yakima ,creek4 7,fig4 #f7 ,illu/ration3 ,lay]s ( pumice on ! floor ( a cirque ne> ,p>adise ,p>k4 ,! yell[ b$ at ! bottom is lay] ,o1 :i* 0 erupt$ by ,m\nt ,mazama volcano at ! site ( ,crat] ,lake1 ,oregon1 ab\t #f1fjj ye>s ago4 ,! yell[i%-br[n lay] a few in*es above lay] ,o is lay] ,d1 a pumice t 0 erupt$ by ,m\nt ,ra9i] betwe5 #e1hjj & #f1fjj ye>s ago4 ,! light-yell[i%-br[n pumice b$ at ! top ( ! outcrop is lay] ,y1 :i* orig9at$ at ,m\nt ,/4 ,hel5s volcano betwe5 #c1bej & #d1jjj ye>s ago4 ,photograph by ,d4 ,r4 ,mull9eaux1 ,u4,s4 ,geological ,survey4 7,fig4 #g7 ,d4 ,r4 ,mull9eaux ( ! ,u4,s4 ,geological ,survey has /udi$ 9 detail ! pumice deposits ( ,m\nt ,ra9i] ,national ,p>k4 ,"o ( 8 fir/ & mo/ important discov]ies 0 t ev5 ?\gh "s pumice lay]s are spread widely ov] ! p>k1 !y 7 erupt$ f o!r volcanoes4 ,/rangely en\gh1 "o lay] is ?ick] & m widespread ?an any rec5t pumice erupt$ by ,m\nt ,ra9i]4 ,we c cle>ly see t ^! =eign pumice lay]s did n come f ,m\nt ,ra9i]1 = !y ?ick5 & co>s5 s\?w>d1 away f ! p>k4 ,! olde/ 0 erupt$ by ,m\nt ,mazama volcano at ! site ( ,crat] ,lake1 ,oregon1 ab\t #f1fjj ye>s ago2 ?is pumice =ms a yell[i%-orange lay] ab\t #b in*es ?ick ne>ly ev]y:]e 9 ! p>k4 ,! pumice has a texture l t ( s&y fl\r1 & x feels gra9y :5 rubb$ betwe5 ! f+]s4 ,x is s f9e gra9$ because ( ! great di/ance to its s\rce1 #bej miles due s\? ( ,m\nt ,ra9i]4 ,ne> ,crat] ,lake ?is same pumice consi/s ( l>ge *unks & is _m feet ?ick4 ,two o!r =eign pumice deposits 9 ! p>k 7 erupt$ by ,m\nt ,/4 ,hel5s1 a symmetrical "y volcanic cone ab\t #ej miles s\?we/ ( ,m\nt ,ra9i]4 ,! old] ( ! two is betwe5 #c1bej & #d1jjj ye>s old2 x =ms a blanket ( yell[ s&-siz$ pumice t is z mu* z #bj in*es ?ick 9 ! we/]n "p ( ! p>k4 ,! y\ng] pumice lay] is mo/ conspicu\s at ! gr\nd surface 9 ! ea/]n "p ( ! p>k1 :]e x is z mu* z #d in*es ?ick & resembles a f9e :ite s&4 ,x is ab\t #dej ye>s old4 ,illu/ration3 ,m\nt ,/4 ,hel5s z x appe>s f ,m\nt ,ra9i]4 ,an inconspicu\s b$ ( pumice records ! fir/ eruption ( ,m\nt ,ra9i] t occurr$ aft] ,ice ,age glaci]s melt$ back to ! slopes ( ! volcano4 ,x c be f\nd on ! ea/ side ( ! m\nta9 f ,gr& ,p>k s\? to ,ohanapeco% campgr\nd 7fig4 #h74 ,9 roadcuts ne> ! ea/ end ( ,yakima ,p>k 7,sunrise7 ! pumice =ms a ru/y-br[n b$ ab\t #d in*es ?ick :i* conta9s fragm5ts z mu* z #b in*es across4 ,wood f a ?9 lay] ( peat j above ! pumice 0 dat$ by its cont5t ( radioactive c>bon z ab\t #h1gej ye>s old2 ?us1 ! pumice is ev5 old]4 ,we call ?is pumice lay] ,r = conv5i5ce2 o!r lett] symbols h be5 assign$ to ! y\ng] lay]s 7table #a74 ,illu/ration3 ,g5]aliz$ di/ribution ( "s pumice lay]s )9 ,m\nt ,ra9i] ,national ,p>k4 ,! pumice ( lay]s ,w & ,y 0 erupt$ by ,m\nt ,/4 ,hel5s2 all ! o!r pumice orig9at$ at ,m\nt ,ra9i]4 ,lett]s repres5t ! foll[+ localities3 ,c1 ,c\g> ,rock campgr\nd2 ,i1 ,ipsut ,creek campgr\nd2 ,l1 ,longmire2 ,m1 ,m[i* ,lake2 ,o1 ,ohanapeco% campgr\nd2 ,p1 ,p>adise ,p>k2 ,s1 summit crat]2 ,t1 ,tipsoo ,lake2 ,w1 ,:ite ,riv] campgr\nd2 & ,y1 ,yakima ,p>k4 ,bas$ on /udies by ,d4 ,r4 ,mull9eaux4 7,fig4 #h7 ,illu/ration3 ,lay] ,x 7,betwe5 #aaj & #aej ye>s old7 ,illu/ration3 ,lay] ,c 7,betwe5 #b1aej & #b1ejj ye>s old7 ,illu/ration3 ,lay] ,d 7,betwe5 #e1hjj & #f1fjj ye>s old7 ,illu/ration3 ,lay] ,l 7,betwe5 #e1hjj & #f1fjj ye>s old7 ,illu/ration3 ,lay] ,r 7,m ?an #h1gej ye>s old7 ,illu/ration3 ,lay] ,w 7l9e patt]n71 & ,lay] ,y 7/ipple patt]n7 7,ab\t #dej ye>s old & #c1bej to #d1jjj ye>s old1 respectively7 ,,table #a4--;,*>act]i/ics1 s\rces1 & ages ( pumice lay]s1 ,m\nt ,ra9i] ,national ,p>k ,bas$ on /udies by ,d4 ,r4 ,mull9eaux ,common range ( ?ickness 9 p>k ,pumice ,we/ ,ea/ ,common ,color ,s\rce ,approximate lay] side side range 9 age 9 #aifh1 7in*es7 7in*es7 diamet] or limit+ ( pumice dates 7ye>s fragm5ts ago7 7in*es7 ,x ,abs5t #a -#b ,light olive ,m\nt #ajj-aej gray ,ra9i]4 ,w #j-a #a-c ,m$ium ,:ite ,m\nt ,/4 #bdej s& ,hel5s4 ,c ,abs5t #a-h -#h ,br[n ,m\nt #b1aej-b1ejj ,ra9i]4 ,y #e-bj #a-e ,co>se ,yell[ ,m\nt ,/4 #c1bej-d1jjj s& ,hel5s4 ,d ,abs5t #j-f -#f ,br[n ,m\nt #e1hjj-f1fjj ,ra9i]4 ,l ,abs5t #j-h -#b ,br[n ,m\nt #e1hjj-f1fjj ,ra9i]4 ,o #a-c #a-c ,fl\rlike ,yell[i% ,m\nt ,ab\t #f1fjj to f9e orange ,mazama4 s& ,r ,abs5t #j-e -#a ,r$di% ,m\nt #h1gej-aa1jjj8 br[n ,ra9i]4 ,! next two eruptions ( ,m\nt ,ra9i] occurr$ betwe5 #e1hjj & #f1fjj ye>s ago4 ,aga91 pumice spread ov] ! area ea/ ( ! volcano4 ,! old] pumice1 :i* we call lay] ,l1 cov]s a b& only a few miles wide t ext5ds to ! s\!a/ f ! volcano 7fig4 #h74 ,! y\ng] pumice1 lay] ,d1 cov]s an area at lea/ #aj miles wide directly ea/ ( ! volcano4 ,! di/ribution ( bo? deposits %[s t !re 7 /rong directional w9ds dur+ ! eruptions4 ,! long1 n>r[ patt]n ( lay] ,l probably 0 caus$ by /rong nor?we/]ly w9ds dur+ a %ort-liv$ eruption4 ,! patt]n ( lay] ,d 0 caus$ by w9ds f ! we/4 ,"s "t dur+ ^! eruptions1 hot volcanic bombs & rock fragm5ts 7 ?r[n out ( ,m\nt ,ra9i]'s crat] & fell onto surr\nd+ areas ( sn[ & ice4 ,:olesale melt+ result$1 & floods desc5d$ ! ea/ flank ( ! volcano c>ry+ millions ( tons ( a%1 newly erupt$ rock debris1 & breadcru/ bombs4 ,breadcru/ bombs seem to be solid rock1 b if y w\ld break "o op51 y w\ld f9d t ! inside is holl[ or is fill$ ) a spongy mass ( black glass4 ,_! out] surfaces are crack$ l ! cru/ ( a loaf ( h>d-cru/$ bread 7fig4 #i71 s we call !m breadcru/ bombs4 ,!y orig9at$ z blobs ( s(t1 r$-hot lava :i* 7 ?r[n out ( ! volcano's crat]4 ,z ! masses ar*$ ?r\gh ! air1 !y quickly *ill$ on ! outside1 & a h>d5$ sk9 =m$ ar\nd ! /ill hot & pla/ic core4 ,z _! outsides cool$1 gas pressure 9 _! hot int]iors caus$ ! bombs to exp& slightly & _! solidifi$ out] sk9 to crack4 ,:5 !y /ruck ! gr\nd1 _m ( ! bombs became flatt5$ on "o side1 b !y 7 /ill pla/ic & /icky en\gh to rema9 :ole4 ,bombs c be f\nd 9 two deposits t =m ! s\? bank ( ! ,:ite ,riv] ab\t half a mile d[n/ream f ! ,:ite ,riv] campgr\nd4 ,! deposits are mudfl[s caus$ by ! mix+ ( hot rock debris ) ! wat] f melt$ sn[ & ice4 ,z ! mudfl[s mov$ d[n ! valley floor !y mu/ h resembl$ fl[+ masses ( wet concrete4 ,m\nt ,ra9i] erupt$ sev]al times betwe5 ab\t #b1ejj & #b1jjj ye>s ago4 ,dur+ "o ( ! fir/ eruptions1 a mass ( hot a%1 rock fragm5ts1 & breadcru/ bombs avalan*$ d[n ! side ( ! volcano & buri$ ! floor ( ! ,s\? ,puyallup ,riv] valley4 ,al?\gh ?is hot mass fl[$ l a wet mudfl[1 ! temp]ature ( ! rock debris 0 above #fjj;,f4 ,?us1 if any wat] _h be5 pres5t1 x w\ld h be5 9 ! =m ( /eam4 ,y c see ! result+ deposit 9 cuts along ! ,we/ ,side ,road on bo? sides ( ! bridge across ! ,s\? ,puyallup ,riv]4 ,innum]able bombs h roll$ f ! cuts into ! dit*es beside ! road4 ,a *>coal log f\nd 9 ! deposit _h a radioc>bon age ( ab\t #b1ejj ye>s4 ,illu/ration3 ,a l>ge breadcru/ bomb enclos$ 9 a mudfl[ deposit t consi/s ( a mixture ( volcanic a% & rock fragm5ts4 ,! outcrop is on ! s\? bank ( ! ,:ite ,riv] ab\t half a mile d[n/ream f ! ,:ite ,riv] campgr\nd4 7,fig4 #i7 ,l>ge am\nts ( pumice 7 ?r[n out ( ! volcano at ! same "t z ! bombs or soon aft]4 ,! pumice cov]s mo/ ( ! ea/]n half ( ! p>k1 & fragm5ts are scatt]$ z f> s\?we/ z ,pyramid ,peak & z f> nor?we/ z ,spray ,p>k4 ,?is pumice1 call$ lay] ,c1 is especially ?ick & co>se at ,yakima ,p>k & ,burr\ghs ,m\nta91 :]e x lies at ! gr\nd surface 7fig4 #aj74 ,"h ! light-br[n lay] is #e-f in*es ?ick & consi/s ( irregul>ly %ap$ pumice fragm5ts z mu* z sev]al in*es across4 ,m+l$ ) ! pumice fragm5ts are fi/-siz$ *unks ( light-gray rock t probably 7 simultane\sly ?r[n out ( ! volcano by viol5t explosions4 ,"s ( ^! angul> rocks 7 hurl$ z f> z ,%r9] ,peak1 #aa miles ea/ ( ,m\nt ,ra9i]'s summit4 ,illu/ration3 ,pumice lay] ,c1 :i* consi/s ( light-br[n fragm5ts1 lies at ! gr\nd surface ov] mu* ( ! ea/]n "p ( ! p>k4 7,fig4 #aj7 ,! eruptive p]iod 0 climax$ by ! build+ ( ! volcano's pres5t summit cone1 :i* is at lea/ #a1jjj feet high & #a mile across at its base4 ,al?\gh dw>f$ by ! trem5d\s bulk ( ,m\nt ,ra9i]1 x is a little l>g] ?an ! cone ( ! well-kn[n ,mexican volcano ,p>cut9 t appe>$ 9 #aidc & erupt$ until #aieb4 ,m\nt ,ra9i]'s pres5t summit cone 0 built )9 a broad depression at ! top ( ! ma9 volcano t _h be5 =m$ ne>ly #d1jjj ye>s e>li] 7fig4 #aa2 see p4 #dj74 ,! cone consi/s ( a s]ies ( ?9 black lava fl[s1 & its top is ind5t$ by two ov]lapp+ crat]s4 ,rocks ar\nd ! crat]s are /ill w>m 9 places1 & /eam v5ts melt caves 9 ! summit icecap4 ,! fir/ climb]s :o rea*$ ! top ( ! m\nta91 9 #ahgj1 sp5t ! night 9 "o ( ^! caves1 z h _m b5ight$ climb]s s9ce4 ,illu/ration3 ,! sn[-cov]$ lava cone lies 9 a depression #a miles wide at ! summit ( ! volcano4 ,! cone 0 probably built ab\t #b1jjj ye>s ago4 ,lib]ty ,cap is to ! left & ,po9t ,success is to ! "r4 ,! cliffs bel[ & to ! "r ( ,lib]ty ,cap enclose ,sunset ,amphi!at]4 7,fig4 #aa7 ,ev5 ?\gh ! lava fl[s t =m$ ! summit cone 7 relatively %ort1 _! eruption greatly affect$ "s valleys at ! base ( ! volcano4 ,! hot lava melt$ sn[ & ice at ! volcano's summit1 caus+ floods t ru%$ d[n ! ea/ & s\? sides4 ,:5 ! floods rea*$ ! valley floors1 !y pick$ up great quantities ( loose rock debris & c>ri$ x d[n/ream1 sometimes =m+ mudfl[s4 ,! result+ flood & mudfl[ deposits rais$ ! floors ( ! ,:ite & ,nisqually ,riv] valleys z mu* z #hj feet high] ?an !y are today4 ,^! valley floors1 z well z sev]al o!rs1 !n became broad wa/es ( b>e s& & gravel t ext5d$ beyond ! p>k b\nd>ies4 ,lat]1 ! riv]s cut d[n to _! pres5t levels1 b !y left remnants ( ! flood & mudfl[ deposits z t]races or b5*es along ! sides ( ! valleys4 ,y c camp on su* a t]race 9 ! ,nisqually ,riv] valley at ! ,c\g> ,rock campgr\nd4 ,! ,:ite ,riv] campgr\nd occupies a simil> t]race 9 ! ,:ite ,riv] valley4 ,:5 did ,m\nt ,ra9i] erupt la/8 ,! mo/ rec5t pumice eruption 0 j a little ov] a c5tury ago4 ,h[ev]1 betwe5 #ahbj & #ahid1 obs]v]s report$ at lea/ #ad eruptions4 ,"s ( ^! may h be5 j l>ge du/ cl\ds1 caus$ by rockfalls1 t 7 mi/ak5 = cl\ds ( newly erupt$ a%4 ,o!r cl\ds may h be5 f g5u9e eruptions t left no recognizable deposits4 ,d4 ,r4 ,mull9eaux has f\nd t at lea/ "o eruption ( t era did spread pumice ov] an area ea/ ( ! volcano betwe5 ,burr\ghs ,m\nta9 & ,indian ,b> to a di/ance ( at lea/ #f miles f ! crat]4 ,pieces ( ! pumice1 lay] ,x1 are light br[ni% gray & z l>ge z #b in*es across4 ,we f9d only scatt]$ fragm5ts ( ! pumice1 & n[h]e are !y 9 a cont9u\s lay]4 ,:]e ! ,x pumice is directly on top ( lay] ,c1 we _c tell !m ap>t4 ,! be/ areas = u to /udy ! y\ng] pumice1 !re=e1 are glacial mora9es =m$ )9 ! la/ #aej ye>s1 because no pumice o!r ?an lay] ,x is pres5t on ! mora9es4 ,=tunately1 ,r4 ,s4 ,sigafoos & ,e4 ,l4 ,h5dricks ( ! ,u4,s4 ,geological ,survey h det]m9$ ! ages ( ! mora9es by c\nt+ ! gr[? r+s ( trees on !m4 ,_! /udies %[ t ! pumice 0 erupt$ betwe5 ab\t #ahbj & #ahed4 ,capta9 ,john ,frmont1 an e>ly explor] ( ! ,oregon ,t]ritory1 record$ t ,m\nt ,ra9i] 0 erupt+ 9 ,novemb] #ahdc1 b 8 j\rnals give no details4 ,o!rs h report$ eruptions 9 #ahbj1 #ahdf1 #ahed1 & #aheh4 ,pumice lay] ,x probably 0 erupt$ dur+ "o or m ( ^! times1 b we d n "k exactly :54 ,& w ,m\nt ,ra9i] erupt aga98 ,we ?9k t x w1 b we n[ h no sure way ( pr$ict+ ! "t1 ! k9d1 or ! scale ( future eruptions4 ,:y ,glaci]s8 ,we frequ5tly he> ! "q3 8,:y are !re glaci]s on ,m\nt ,ra9i]80 ,a glaci] =ms :]ev] sn[fall repeat$ly exce$s melt+ ov] a p]iod ( ye>s4 ,above #f1ejj-g1jjj feet on ,m\nt ,ra9i]1 m ?an #ej feet ( sn[ falls ea* w9t]1 & n all ( x melts be=e ! next w9t]4 ,! survival ( ?is sn[ f "o ye> to ! next dep5ds p>tly on ! cool] temp]atures at ! high] altitudes1 & p]haps also on ! some:at deep] sn[falls !re4 ,illu/ration3 ,two ice /reams meet to =m ! half-mile-wide ,c[litz ,glaci]4 ,"o heads on ! flank ( ! volcano & ! o!r 7,+raham ,glaci]7 at ! summit4 ,! firnl9e is a %ort di/ance above ! junction ( ! glaci]s4 ,! high b>e embankm5t at ! extreme "r is a lat]al mora9e t 0 =m$ ab\t #ajj ye>s ago :5 ! glaci] 0 ?ick] & ab\t #a miles long]4 7,fig4 #ab7 ,,little ,,tahoma ,,peak ,,m\nt ,,ra9i] ,,+raham ,,glaci] ,,c[litz ,,glaci] ,a l9e t m>ks ! limit on a m\nta9 above :i* sn[ p]si/s f "o w9t] to ! next is call$ ! annual sn[l9e1 & ?is l9e on a glaci] is call$ ! firnl9e 7fig4 #ab74 ,above ! firnl9e1 sn[ t falls ea* ye> packs d[n & *anges into glaci] ice z air is sl[ly =c$ out ( x4 ,?is "p ( ! glaci] is its accumulation area1 :]e m sn[ falls ea* ye> ?an is lo/ by melt+4 ,bel[ ! firnl9e is ! ablation area1 :]e melt+ pr$om9ates4 ,! firnl9e on ,m\nt ,ra9i]'s glaci]s has be5 well above #f1ejj feet 9 rec5t ye>s4 ,b "s glaci]s ext5d to altitudes bel[ #e1jjj feet--t is1 f> d[n into ! ablation area4 ,!y d ?is by sl[ly fl[+ d[nhill4 ,solid ice fl[s by slid+ on ! h>d b$rock "u ! glaci] & by slipp+ along ! innum]able surfaces )9 ! ice cry/als t make up ! glaci]4 ,! rate ( fl[ & ! rate ( ablation gov]n ! di/ance a glaci] ext5ds d[n into ! ablation zone4 ,if ^! rates rema9 fairly con/ant1 ! glaci] w be 9 balance & its size w be ab\t ! same f ye> to ye>4 ,b if *ang+ wea!r patt]ns affect ! rates ( ablation or accumulation1 or bo?1 ! glaci] w ei!r become small] or gr[ l>g]4 ,! *ange y are mo/ likely to notice is 9 ! position ( ! glaci]'s t]m9us1 :i* may ei!r rec$e or advance1 b precise measurem5ts ( ! upp] rea*es ( a glaci] also %[ volume *anges !re1 "s ( :i* may n affect ! glaci]'s t]m9us = _m ye>s1 if ev]4 ,crevasses are a glaci]'s mo/ awesome features & are a con/ant haz>d = climb]s4 ,!y =m :]e adjac5t p>ts ( a glaci] are mov+ at diff]5t spe$s4 ,"s ( ,m\nt ,ra9i]'s glaci]s may be fl[+ at a spe$ ( sev]al ?\s& feet p] ye> along _! c5t]s b at a mu* sl[] rate along _! m>g9s4 ,?is unequal rate ( fl[ produces /resses 9 ! ice t cause x to break4 ,gr\ps ( crevasses (t5 =m :]e ! glaci] fl[s ov] a /eep place 9 its b$4 ,! ice moves fa/] "h1 & pulls ap>t1 & a crevasse is =m$4 ,al?\gh a l>ge crevasse may seem to be bottomless to ! obs]v]1 mo/ crevasses are less ?an #ajj feet deep because ice pressure t5ds to close ! op5 spaces 9 ! ice bel[ t dep?4#c ,ice cov]s #cg squ>e miles ( ! p>k today4 ,individual glaci]s t make up ?is ice blanket are plac$ into ?ree gr\ps1 dep5d+ on _! place ( orig94 ,^? ( "o gr\p orig9ate at ! volcano's summit & fl[ f> d[n ! valleys t radiate f ! cone4 ,mo/ ( ! sn[ t n\ri%es ^! glaci]s probably falls on !m at altitudes well bel[ ! summit4 ,! l>ge/ examples ( ! gr\p are ! ,emmons1 ,nisqually1 & ,tahoma ,glaci]s4 ,glaci]s ( ! second gr\p orig9ate on ! flanks ( ! volcano1 mo/ly at altitudes betwe5 #g1jjj & #aj1jjj feet4 ,?is gr\p is repres5t$ by ! ,s\? ,tahoma1 ,c>bon1 & ,int] ,glaci]s4 ,glaci]s ( ! ?ird gr\p are on nor?-fac+ slopes 9 ! m\nta9s ar\nd ,m\nt ,ra9i]4 ,!y are mo/ly at altitudes ( ab\t #f1jjj feet1 & !y owe _! exi/5ce to locations well protect$ f sol> heat4 ,glaci]s repres5t+ ?is gr\p are ! ,unicorn & ,p9nacle ,glaci]s 9 ! ,tatoo% ,range1 a small unnam$ glaci] ne> ! we/ end ( ,burr\ghs ,m\nta91 & ! some:at l>g] ,s>v5t ,glaci]s ea/ ( ,m\nt ,ra9i]4 ,"w ,habits ( ,glaci]s ,glaci]s are extremely capable work]s4 ,_! "w includes erosion1 transportation1 & deposition4 ,! smoo!d & groov$ b$rock at ,box ,canyon & at _m po9ts along ! trail to ! ice caves ne> ,p>adise ,p>k %[s erosion ( rock by glaci] ice4 ,rock fragm5ts c>ri$ by glaci]s cut grooves 9 ! h>d b$rock & poli% its surface 7fig4 #ac74 ,al?\gh any "o rock fragm5t might scrape away only #a millimet] ( rock along a s+le groove1 ! total effect is great :5 multipli$ by c\ntless ?\s&s ( simil> fragm5ts rasp+ a b$rock surface = hundr$s or ?\s&s ( ye>s4 ,glaci] ice may also break *unks ( rock loose z x ov]rides !m & may ev5 pl[ up sections ( s(t] rocks4 ,glaci]s transport n only ! rocks t !y qu>ry & scrape f _! b$s b also1 m conspicu\sly1 ^? t fall onto _! surfaces f ne>by cliffs4 ,^! fall+ rocks range 9 size f t9y p>ticles to individual masses t weigh t5s ( ?\s&s ( tons1 l ^? t fell onto ,emmons ,glaci] f ,little ,tahoma ,peak 9 #aifc4 7,see p4 #ce47 ,a glaci] deposits mo/ rock debris at its t]m9us4 ,! /eep sn\t ( any major glaci] is a dang]\s place to approa* closely because rock debris almo/ con/antly falls1 rolls1 & slides d[n ! melt+ ice faces4 ,mu* ( ?is debris collects at ! ice m>g91 & if ! m>g9 /ays 9 "o place long en\gh a ridge-%ap$ end mora9e ( rock debris =ms along ! ice front 7fig4 #ad74 ,if su* a mora9e =ms across ! front ( a glaci] at its f>!/ advance x is call$ a t]m9al mora9e4 ,end mora9es t =m z ! ice rec$es are call$ recessional mora9es 7fig4 #ae74 ,ridges ( rock debris t =m along ! sides ( a glaci] are call$ lat]al mora9es 7fig4 #ab74 ,"s rec5t mora9es ( mod]n glaci]s are only a few feet away f ! pres5t ice m>g92 o!rs1 =m$ ?\s&s ( ye>s ago dur+ ! mo/ rec5t major glaciation1 are on ridgetops & valley sides or floors miles away f mod]n glaci]s4 ,by exam9+ ! %ape & location ( ^! mora9es1 we c recon/ruct ! size & "* ( pa/ glaci]s1 z we w see 9 ! next section4 ,illu/ration3 ,glaci]-smoo!d & groov$ rock along ! ,wond]l& ,trail betwe5 ,indian ,b> & ,panh&le ,gap4 7,fig4 #ac7 ,illu/ration3 ,a muddy grayi%-blue lake sev]al hundr$ feet long lies beh9d a small horse%oe-%ap$ end mora9e ( ,flett ,glaci]1 on ! nor?we/ side ( ,m\nt ,ra9i]4 ,! glaci] is mo/ly out ( view to ! left4 7,fig4 #ad7 ,glaci]s erode1 transport1 & deposit huge quantities ( rock debris4 ,s d _! c[ork]s1 ! melt-wat] /reams4 ,^! turbul5t /reams fl[ f tunnels b5ea? e glaci]1 & _! degree ( mudd9ess r\ghly %[s h[ active ! glaci] is4 ,glaci]s t move v sl[ly1 or t are /agnant1 produce relatively cle> melt wat] because !y are n actively erod+ b$rock4 ,9 contra/1 /reams ( muddy wat] t look l *ocolate milk (t5 come f v active or 8live0 glaci]s4 ,^! /reams c>ry rock debris rang+ f fl\r-size p>ticles to l>ge b\ld]s4 ,y c s5se ! c>ry+ p[] ( ?is swiftly mov+ wat] on w>m summ] days1 :5 l>ge cobbles & b\ld]s are bump+ along 9 a /ream swoll5 by rapid glaci] melt+4 ,al?\gh y c r>ely see ^! b\ld]s1 y c he> _! con/ant l[ ?und]4 ,_! repeat$ impacts on o!r b\ld]s 9 ! /reamb$ w vibrate ! ne>by /reambanks b5ea? y\r feet4 ,hik]s (t5 f9d t a melt-wat] /ream safe to cross 9 ! e>ly morn+ ( a w>m summ] day is an impassable torr5t at ! same spot by e>ly aft]noon4 ,illu/ration3 ,f\r curv$ recessional mora9es are spread ov] a di/ance ( #b1jjj feet on ! valley floor ( ,fry+pan ,creek4 ,!y 7 =m$ )9 ! la/ few hundr$ ye>s z ,fry+pan ,glaci] lo/ volume & %rank back t[>d its pres5t position above a l9e ( cliffs4 7,fig4 #ae7 ,a melt-wat] /ream g5]ally deposits co>se mat]ial :]ev] ! slope ( ! valley floor decreases & ! /ream loses "s ( its velocity & c>ry+ p[]4 ,only a flood may move ! b\ld]s f>!r d[n/ream4 ,h[ev]1 ! curr5t c>ries f9e mat]ial f> d[n/ream to deposit x 9 lakes1 9 ,puget ,s\nd1 or 9 ! ,pacific ,ocean4 ,! ,puyallup ,riv]1 = example1 is /ill v muddy :]e x ent]s ,puget ,s\nd at ,tacoma1 m ?an #dj miles f its s\rce 9 ! glaci]s on ,m\nt ,ra9i]4 ,dur+ ! la/ glaciation1 :5 glaci]s 7 mu* l>g] ?an !y are n[1 melt-wat] /reams c>ry+ great quantities ( s& & gravel built valley floors up to levels t5s ( feet high] ?an !y are today4 ,lat]1 z ! glaci]s grew small]1 ! riv]s cut d[n into _! valley floors & remnants ( ! s& & gravel deposits 7 left /&+ 9 b5*es or t]races along ! sides ( ! valleys4 ,y c see a good example ( su* a t]race 9 ! ,nisqually ,riv] valley beyond ,a%=d1 :i* is #e miles we/ ( ! p>k4 ,y cross x on ! highway t leads to ! p>k4 ,cuts b5ea? ! t]race reveal deposits ( s&1 cobbles1 & b\ld]s t look ! same z ^? deposits be+ =m$ today by melt-wat] /reams4 ,! t]race we/ ( ,a%=d 0 =m$ a little m ?an #ae1jjj ye>s ago1 :5 a glaci] ext5d$ d[n ! ,nisqually ,riv] valley to ! vic9ity ( ,a%=d4 ,ye/]day's ,glaci]s ,m\nt ,ra9i]'s great sprawl+ cone w\ld seem incomplete )\t ! gli/5+ %eets ( ice t desc5d its flanks4 ,we h reason to believe t ! volcano has borne glaci]s ev] s9ce its orig9--sometimes small] ?an n[1 at o!r times va/ly l>g]4 ,m\nt ,ra9i] probably />t$ to gr[ dur+ ! middle "p ( ! ,plei/oc5e ,epo*1 or ,ice ,age1 :i* began m ?an #a million ye>s ago1 b glaci]s _h cov]$ ?is "p ( ! m\nta9s ev5 be=e ! volcano appe>$4 ,masses ( rock debris =m$ by anci5t glaci]s occur b5ea? lava fl[s f ,m\nt ,ra9i] on ! we/ side ( ,mazama ,ridge j upslope f ,n>ada ,falls1 on ! nor? side ( ,glaci] ,bas91 & at a few o!r places 9 ! p>k4 ,m\nt ,ra9i] may h rea*$ its pres5t size by ab\t #ge1jjj ye>s ago4 ,s9ce t "t great icefields & glaci]s h =m$ at lea/ ?ree times on ! slopes ( ! volcano & 9 ! ne>by m\nta9s4 ,dur+ ! fir/ two glaciations1 ice completely buri$ ! flanks ( ! volcano & ! surr\nd+ m\nta9s1 except = ! v highe/ ridges & peaks4 ,^! great ice masses sl[ly fl[$ d[n all ! valleys t head at ,m\nt ,ra9i]4 ,! glaci] 9 ! ,c[litz ,riv] valley1 = example1 ext5d$ #fe miles f ! volcano & rea*$ a po9t ab\t #cc miles we/ ( ! community ( ,r&le4 ,deposits ( ! y\ng] ( ^! two glacial episodes c be se5 9 cuts along ! ,m[i* ,lake ,road = a di/ance ( ab\t #a miles inside ! p>k b\nd>y4 ,! glacial deposits 7 orig9ally m widespread1 b 9 mo/ ( ! p>k !y h be5 remov$ by erosion or cov]$ by ! deposits ( yet y\ng] glaci]s4 ,illu/ration3 ,ext5t ( glaci]s 9 ! ,cascade ,range ne> ,m\nt ,ra9i] betwe5 ab\t #ae1jjj & #be1jjj ye>s ago4 ,arr[s %[ ! direction ( ice movem5t2 solid black repres5ts mod]n glaci]s on ,m\nt ,ra9i]4 7,fig4 #af7 ,dur+ ! mo/ rec5t major glaciation ( ! p>k1 :i* la/$ f r\ghly #be1jjj to #aj1jjj ye>s ago1 ice aga9 %ea!d ! slopes ( ! volcano1 b glaci]s 9 ! ne>by m\nta9s 7 small] ?an be=e4 ,mo/ ( ! glaci]s orig9at$ at ! valley heads1 :]e !y g\g$ out c\ntless b[l-%ap$ b$rock bas9s call$ cirques4 ,_m ( ! bas9s held lakes aft] ! glaci]s disappe>$4 7,see frontispiece47 ,hik]s on ! trail to ! ,p>adise ice caves cross ! floor ( a typical cirque at ! head ( ,p>adise ,valley4 ,f ! ,sunrise ,visitor ,c5t] at ,yakima ,p>k y c walk a %ort di/ance to a po9t along ! cre/ ( ! ,s\rd\gh ,m\nta9s & /& at ! rim ( a deep nor?-fac+ cirque4 ,ice orig9at+ 9 ?is cirque & 9 ! cirques adjac5t to x mov$ nor?w>d d[n ! valley ( ,huckleb]ry ,creek at lea/ z f> z ! p>k's nor? b\nd>y 7fig4 #af74 ,^! glaci]s left mo/ valley walls 9 ! p>k cov]$ ) rock debris4 ,lat]al mora9es c be se5 along ! highway at & j ea/ ( ,rickseck] ,po9t 7fig4 #ag74 ,o!r glacial deposits are especially well display$ 9 roadcuts along ! nor? wall ( ! ,:ite ,riv] valley4 ,illu/ration3 ,lat]al mora9e ( rock debris at ,rickseck] ,po9t4 ,x 0 =m$ by ,nisqually ,glaci] :5 ! glaci] 0 at lea/ #a1jjj feet ?ick & ab\t #ae miles long] ?an x is today4 7,fig4 #ag7 ,a little m ?an #ae1jjj ye>s ago ! long glaci]s began to %r9k & rec$e4 ,by #aa1jjj ye>s ago !re 0 only ab\t z mu* ice on ,m\nt ,ra9i] z !re has be5 )9 ! la/ c5tury4 ,!n1 dur+ a %ort p]iod ( r5ew$ glaci] gr[?1 mo/ glaci]s exp&$ %ort di/ances & new ones appe>$ 9 cirques f :i* ice _h disappe>$ only a %ort "t be=e4 ,9 "s ( ^! cirques s mu* rock debris 0 be+ dislodg$ f surr\nd+ cliffs by repeat$ freeze & ?aw t a rock glaci]1 consi/+ mo/ly ( rock fragm5ts b\nd toge!r by ice1 0 =m$4 ,a trail to ! ,huckleb]ry ,creek valley crosses hummocky rock debris left by su* a rock glaci] 9 a cirque on ! s\!a/ side ( ,m\nt ,fremont4 ,a l>g] rock-glaci] deposit lies ab\t #b miles nor? ( ,sunrise ,po9t 9 an ea/-fac+ cirque betwe5 ,! ,palisades & ,hidd5 ,lake 7fig4 #ah74 ,9 o!r cirques1 :]e ! proportion ( ice to rock debris 0 great]1 ! glaci] transport$ ! debris a %ort di/ance =w>d & built a t]m9al mora9e4 ,y c see p>ticul>ly good examples ( mora9es =m$ ab\t #aa1jjj ye>s ago ne> ,tipsoo ,lake1 :]e ! pond s\!a/ ( ! lake is damm$ by a mora9e1 & at ,my/ic ,lake4 ,! ice t =m$ ! t]m9al mora9e at ,my/ic ,lake 0 a tongue ( ,c>bon ,glaci]4 ,9 "s places ! ori5tation or altitude ( ! cirque did n p]mit en\gh sn[ to accumulate to =m a glaci] b j en\gh to create a p]man5t sn[bank4 ,rock debris t fell f ! surr\nd+ cliffs roll$ d[n ^! sn[banks & =m$ l[ ridges at _! toes4 ,su* a ridge is call$ a protalus ramp>t because x is f\nd j 9 front ( ! apron ( rock fragm5ts1 call$ talus1 t lies b5ea? cliffs4 ,a trail at ,sunrise ,po9t leads to protalus ramp>ts along ! nor? side ( ,sunrise ,ridge4 ,dur+ ! la/ #aj1jjj ye>s1 glaci]s h be5 v small by comp>ison ) ! great ice mantles t ov]:elm$ ! p>k e>li]4 ,h[ev]1 glaci]s h gr[n l>g] at lea/ twice j )9 ! la/ #c1jjj ye>s4 ,dur+ bo? ( ^! p]iods mo/ glaci]s 7 slightly l>g] ?an !y are today1 & ice occupi$ mo/ cirques at altitudes above #f1ejj feet--ev5 "s t are n[ free ( ice4 ,! mo/ rec5t "t ( ext5sive glaci] gr[? began at lea/ #hjj ye>s ago1 & v>i\s glaci]s 9 ! p>k rea*$ _! maximum size betwe5 ! mid-#ad? c5tury & ! mid-#ai? c5tury4 ,oddly en\gh1 ev5 ?\gh all ! glaci]s head$ on ,m\nt ,ra9i]1 !y did n all atta9 _! maximum size simultane\sly4 ,! l>ge/ t]m9al mora9e ( ?is mo/ rec5t glacial p]iod 0 built by ,emmons ,glaci] 9 ! ,:ite ,riv] valley 7fig4 #ai74 ,x is n[ l>gely =e/$1 & cores tak5 f ! trees ) a special bor+ tool t does n h>m ! tree %[ ages indicat+ t ! mora9e 0 /able en\gh to p]mit se$l+s to survive on x by ! mid-#ag? c5tury4 ,a simil> b small] t]m9al mora9e built by ,c[litz ,glaci] has trees on x t />t$ to gr[ 9 ! mid-#ad? c5tury4 ,illu/ration3 ,rock-glaci] deposit 7light-gray rubble beyond ! br[n slopes 9 ! =egr\nd7 at ,! ,palisades1 :i* 0 =m$ ab\t #aa1jjj ye>s ago :5 ! climate 0 cold] ?an x is today4 ,rocks fell f ! cliffs 9 su* great quantity t a small glaci] 9 front ( ! cliffs consi/$ ( m rock debris ?an ice4 ,! melt+ ( ! ice left a mass ( brok5 rock sev]al hundr$ feet ?ick :i* cov]s ab\t #hj acres4 7,fig4 #ah7 ,illu/ration3 ,! hummocky end mora9e at ! left /ill _h blocks ( ice buri$ 9 x :5 ?is picture 0 tak5 9 #aied4 ,! front ( ,emmons ,glaci] 0 ne> ! left edge ( ! b>e mora9e 9 ab\t #aijj4 ,n[ ! glaci] ends #a mile f>!r upvalley at ! upp] "r4 ,! valley floor & mora9e 7 buri$ by an avalan*e ( rock debris f ,little ,tahoma ,peak 9 #aifc4 7,fig4 #ai7 ,ne>ly all ! glaci]s gradually decreas$ 9 size aft] ! mid-#ah? c5tury4 ,al?\gh ! %r9kage 0 sometimes int]rupt$ by %ort p]iods ( r5ew$ glaci] gr[?1 by #aiej ! glaci]s at ,m\nt ,ra9i] cov]$ only ab\t two-?irds ( ! area t _h be5 buri$ by ice only a c5tury be=e4 ,! ov]all loss ( volume by ,ra9i]'s glaci]s1 z well z ^? else:]e 9 ! ,pacific ,nor?we/1 0 sl[$ or halt$ by slightly cool] temp]atures & high] precipitation />t+ 9 ! mid-#aidj's4 ,volume increases 9 _! upp] rea*es caus$ ! l>g] glaci]s to gr[ f ye> to ye>1 & s9ce ! e>ly #aiej's ! t]m9uses ( _m glaci]s h be5 advanc+4 ,?is r5ew$ gr[? ( glaci]s is n unique at ,m\nt ,ra9i]--simil> *anges h be5 obs]v$ at o!r glaci]s 9 ! ,cascade ,range & else:]e4 ,l&slides & ,mudfl[s--,pa/1 ,pres5t1 & ,future ,"s ( ! mo/ effective means ( erosion at ,m\nt ,ra9i] are l&slides & mudfl[s4 ,erosion ( ?is k9d is sometimes spectacul>4 ,)9 an int]val ( only m9utes or a few h\rs huge masses ( rock may fall1 slide1 or fl[ (f ! volcano & move f> d[nvalley4 ,l>ge l&slides h occurr$ at _m o!r places 9 ! p>k--"o 9 ! area nor!a/ ( ,m\nt ,ra9i] is s conspicu\s t its s\rce has be5 nam$ ,slide ,m\nta94 ,! ragg$ sc> left by ano!r slide ne> ,gr& ,p>k is aptly call$ ,sc>face4 ,y cross a slide on ! ,ma!r ,memorial ,p>kway 7,u4,s4 ,highway #daj7 j nor? ( ,cayuse ,pass4 ,brok5 & jumbl$ rock debris ( _m sizes bord]s bo? sides ( ! highway !re4 ,?is l&slide broke loose 9 rocks ( ! ,ohanapeco% ,=mation1 slid d[nslope to ! bottom ( ! valley1 & damm$ ,klickitat ,creek to =m ,gho/ ,lake4 ,rocks h also slid d[nslope on ! we/ side ( ,backbone ,ridge & on ! ea/ side ( ! ,ohanapeco% ,riv] valley a %ort di/ance nor? ( ,ohanapeco% campgr\nd4 ,! slide on ,backbone ,ridge is /ill sl[ly mov+ today4 ,ano!r slide moves a few in*es ea* ye> on ! we/ side ( ! ,nisqually ,riv] valley ab\t #a mile nor?we/ ( ! visitor c5t] at ,p>adise ,p>k4 ,y c recognize ! slide by a jagg$ horizontal crack #a1jjj feet long at its top4 ,a f> m spectacul> v>iety ( l&slide occurs :5 a mass ( rock drops f a cliff to =m a rockfall4 ,! l>ge/ rockfalls on ,m\nt ,ra9i] 9 hi/oric "t occurr$ 9 ,decemb] #aifc on ! ea/ flank4 ,masses ( rock hundr$s ( feet across fell repeat$ly f ! /eep nor? face ( ,little ,tahoma ,peak onto ,emmons ,glaci]4 ,! rock masses %att]$ into du/ & c\ntless fragm5ts1 fann$ out across ! glaci]1 !n avalan*$ d[n ! /eep ice surface at trem5d\s spe$4 ,:5 ! avalan*es rea*$ ! end ( ! glaci] !y %ot out into space z %eets ( rock debris4 ,z ^! hurtl+ %eets settl$ t[>d ! valley floor1 a cu%ion ( compress$ air =m$ b5ea? !m1 comp>able to ! air cu%ion t mom5t>ily buoys up a %eet ( plywood t is dropp$ onto a flat surface4 ,air t 0 trapp$ b5ea? ^! spe$+ avalan*es r$uc$ friction & p]mitt$ "o ( ! avalan*es to move almo/ #b miles beyond ! end ( ! glaci]4 ,?is avalan*e pass$ completely ov] a small wood5 gage h\se ab\t #e feet high on ! valley floor )\t damag+ x1 !n ran headlong into ! nor? base ( ,goat ,isl& ,m\nta9 :]e x scrap$ away trees & bu%es4 ,a lat] avalan*e /opp$ j %ort ( ! gage h\se1 & w9d t 0 expell$ f b5ea? ! rock debris bla/$ ! /ill-undamag$ h\se sev]al hundr$ feet =w>d4 ,x n[ re/s 9 ! sc> left by ! e>li] avalan*e on ! side ( ,goat ,isl& ,m\nta94 ,at lea/ sev5 rockfalls & avalan*es desc5d$ f ,little ,tahoma ,peak1 sep>at$ p]haps by only m9utes or h\rs4 ,! r$di%-gray masses ( brok5 & pulv]iz$ rock--"s spread helt]-skelt]1 "s pil$ 9 long %>p-cre/$ ridges--n[ lie on ! valley floor betwe5 ! ,:ite ,riv] campgr\nd & ,emmons ,glaci] 7fig4 #bj74 ,! rockfalls might h be5 caus$ by a /eam explosion ne> ! base ( ,little ,tahoma ,peak4 ,/eam jets & small explosions are n unusual ph5om5a at ,m\nt ,ra9i]1 al?\gh !y nev] h _h su* dramatic effects 9 hi/oric "t4 ,incr$ibly l>g] avalan*es ( rock fell repeat$ly f ! sides ( ,m\nt ,ra9i] dur+ prehi/oric "t4 ,"o su* avalan*e orig9at$ ne> ! summit ( ! volcano & blanket$ ,p>adise ,p>k & ,p>adise ,valley ) a yell[i%-orange mixture ( clay & rocks sometime betwe5 #e1hjj & #f1fjj ye>s ago4 ,y c see ?is avalan*e deposit 9 %all[ cuts along trails & roads 9 ! ,p>adise area4 ,huge blocks ( rock t came d[n ) ! avalan*e are scatt]$ 9 ! mead[s ( ,p>adise ,p>k betwe5 ! visitor c5t] & ,panorama ,po9t4 ,al?\gh ! deposit is n[ less ?an #ae feet ?ick 9 mo/ places1 ! mass t fl[$ d[n ,p>adise ,valley mu/ h be5 #fjj feet ?ick1 because we c f9d remnants ( x on top ( ,mazama ,ridge4 ,a tongue ( ! wet mass fl[$ ?r\gh a l[ saddle ne> ! s\? end ( ,mazama ,ridge & ext5d$ into ! bas9 n[ occupi$ by ! ,reflection ,lakes4 ,y c see ! yell[i%-orange deposit 9 ! fir/ roadcut we/ ( ! lakes1 :]e x lies on top ( gray glacial deposits4 ,illu/ration3 ,avalan*e deposits 9 ! ,:ite ,riv] valley4 ,! rockfalls & avalan*es f ,little ,tahoma ,peak =m$ a mass ( r$di%-gray rock debris t contra/s ) ! d>k] gray glacial debris deposit$ by ,emmons ,glaci] )9 ! la/ c5tury4 ,! avalan*e deposits are ab\t #a1ejj feet across at _! wide/ po9t4 7,fig4 #bj7 ,! avalan*e probably 0 wet :5 x cross$ ! ,p>adise area1 & ! moi/ure 9 x may h already be5 pres5t 9 ! rocks 9 :i* ! avalan*e orig9at$4 ,! mass 0 fluid en\gh to move d[n ! ,p>adise & ,nisqually ,riv] valleys z a mudfl[ hundr$s ( feet ?ick1 & ! result+ deposits ext5d at lea/ #ah miles d[n/ream f ! volcano4 ,! volume ( rock t slid (f to produce ! mudfl[ may h be5 z mu* z #ajj million cubic y>ds--or r\ghly en\gh to cov] a #a-mile-squ>e area to a dep? ( #ajj feet4 ,at ab\t ! same "t z ! ,p>adise avalan*e & mudfl[ occurr$1 a trem5d\s rock mass also slid (f ! ea/ side ( ! volcano 9 ! area betwe5 ,/eamboat ,pr[ & ,little ,tahoma ,peak4 ,?is slide =m$ a mudfl[ on ! floor ( ! ,:ite ,riv] valley t 0 sev]al hundr$ feet deep at ! nor? b\nd>y ( ! p>k & t ext5d$ at lea/ #cj miles beyond ! base ( ! volcano4 ,! mo/ rem>kable feature ( ! deposit left by ?is mudfl[ is its surface1 :i* is dott$ ) scores ( m\nds #e-ce feet high & z mu* z sev]al hundr$ feet 9 diamet]4 ,^! m\nds h cores ( huge rocks :i* are simil> 9 size to ^? scatt]$ on ! surface ( ! avalan*e deposits f ,little ,tahoma ,peak4 ,y c see ! m\nds be/ 9 an area :i* is a few miles nor? ( ! p>k b\nd>y1 we/ ( ! ,:ite ,riv]1 & :i* c be rea*$ by ! ,huckleb]ry ,creek ,=e/ ,road4 ,! total volume ( ?is mudfl[ deposit may be z mu* z "o-fif? ( a cubic mile4 ,^! great l&slides & mudfl[s 7 foll[$ %ortly by ano!r ^: size surpass$ t ( any?+ be=e or s9ce4 ,?is 0 ! rem>kable ,osceola ,mudfl[1 :i* /ream$ d[n ! valleys ( ! ,:ite ,riv] & ,we/ ,=k ab\t #e1hjj ye>s ago4 ,:5 ^! great riv]s ( mud jo9$ 9 ! ,:ite ,riv] valley1 !y =m$ an ev5 l>g] mudfl[ :i* swiftly fl[$ d[nvalley = a di/ance ( #ae miles & !n spread beyond ! ,cascade m\nta9 front into ! ,puget ,s\nd l[l&4 ,!re ! mudfl[ subm]g$ a total area ( m ?an #ajj squ>e miles to dep?s z great z #gj feet & buri$ ! sites ( ! pres5t t[ns ( ,enumclaw & ,buckley4 ,"o tongue ( x ev5 fl[$ into an arm ( ,puget ,s\nd1 s\? ( ,seattle1 t has s9ce be5 fill$ ) riv] deposits to =m ! f]tile valley occupi$ by ! t[ns ( ,k5t1 ,auburn1 ,sumn]1 & ,puyallup4 ,! ,osceola ,mudfl[ is rem>kable 9 t x affect$ areas s f> f its place ( orig94 ,?is long di/ance ( travel 0 due to its great volume1 :i* we e/imate to h be5 m ?an half a cubic mile1 & to ! abundance ( slipp]y clay 9 x4 ,! clay _h be5 =m$ by ! alt]ation ( rocks 9 ! volcano by hot gases & solutions ov] _m c5turies4 ,illu/ration3 ,! nor!a/ flank ( ,m\nt ,ra9i]4 ,a remnant ( ! ,osceola ,mudfl[ lies at ! summit ( ,/eamboat ,pr[ 9 ! c5t]4 ,two & "o-half miles to ! left is ,little ,tahoma ,peak1 f ^: /eep nor? face at lea/ sev5 l>ge masses ( rock fell 9 #aifc4 ,m\nt ,adams volcano c be se5 at ! left1 & ,m\nt ,hood1 ,oregon1 9 ! f> di/ance4 7,fig4 #ba7 ,:]e did ! ,osceola ,mudfl[ orig9ate on ! volcano8 ,?is we mu/ d$uce f sev]al l9es ( evid5ce4 ,! mudfl[ occurr$ s long ago t !re is no hi/orical record1 & volcanic ev5ts s9ce t "t h cov]$ up "p ( ! sc> x left on ! volcano4 ,remnants ( ! ,osceola ,mudfl[ v5e] ! sides & ridges ( ,glaci] ,bas91 & a small am\nt ( x is ev5 pres]v$ at ! top ( ,/eamboat ,pr[1 at an altitude ( #i1gjj feet 7fig4 #ba74 ,?is di/ribution tells u t ! slides responsible = ! mudfl[ orig9at$ some:]e on ! volcano above ,/eamboat ,pr[4 ,b n[ !re is no great *asm 9 ! side ( ! volcano l>ge en\gh to h provid$ a s\rce ( ! mudfl[2 s we mu/ consid] a =m] summit ( ! volcano itself z a possible s\rce4 ,i4 ,c4 ,russell1 "o ( ! fir/ geologi/s to /udy ,m\nt ,ra9i]1 wrote 9 #ahif t ! pres5t summit ( ! volcano consi/s ( a small lava cone4 ,enclos+ ?is cone is a broad depression ^: rim is p>tly pres]v$ at ,gibralt> ,rock1 ,po9t ,success1 & ,lib]ty ,cap 7fig4 #aa74 ,high po9ts on ! rim indicate t ! =m] summit ( ! volcano above an altitude ( ab\t #ad1jjj feet 0 remov$ 9 "s way4 ,! de/ruction ( ! old summit1 :i* may h rea*$ a height ( #af1jjj feet1 left a broad ea/-fac+ depression 9 ! top ( ! volcano betwe5 ,gibralt> ,rock & ,russell ,cliff4 ,! depression has s9ce be5 mo/ly fill$ by ! rec5t lava cone4 ,y c see ^! features be/ f high po9ts ea/ ( ! m\nta94 ,our be/ explanation ( h[ ! =m] top ( ! volcano 0 remov$ also solves ! problem ( f9d+ an adequate s\rce ( mat]ial = ! ,osceola ,mudfl[4 ,be=e #e1hjj ye>s ago1 ! topmo/ "p ( ,m\nt ,ra9i] probably consi/$ ( rock t _h be5 weak5$ by hot volcanic fumes & solutions & p>tly conv]t$ to clay4 ,!n1 ?is mass ( weak rock 0 jo/l$ (f or pu%$ (f by a volcanic explosion & slid d[n ! nor!a/ side ( ! volcano4 ,"o or m ( ^! mighty avalan*es ( moi/ clay & rock result$ 9 ! ,osceola ,mudfl[4 ,l>ge avalan*es h also occurr$ _m times dur+ ! la/ #c1jjj ye>s on ! we/ side ( ! volcano4 ,sunset ,amphi!at] 7fig4 #aa7 is "p ( ! l>ge sc> left by !m4 ,ab\t #b1hjj ye>s ago "o ( ^! avalan*es creat$ a mudfl[ 9 ! valleys ( ! ,s\? ,puyallup ,riv] & ,tahoma ,creek t 0 tempor>ily deep en\gh to subm]ge ,r\nd ,pass 7on ! ,we/ ,side ,road7 to a dep? ( ne>ly #djj feet4 ,?is is especially rem>kable :5 we see t ,r\nd ,pass itself is #fjj-gjj feet above ! ne>by valley floors4 ,ano!r deep mudfl[1 />t$ by an avalan*e at ,sunset ,amphi!at]1 mov$ d[n ! ,puyallup ,riv] valley ab\t #fjj ye>s ago & buri$ ! site ( ! pres5t t[n ( ,ort+ 9 ! ,puget ,s\nd l[l& "u #ae feet ( mud & rock4 ,table #b4--,summ>y ( important geologic ev5ts 9 ! hi/ory ( ,m\nt ,ra9i] ,national ,p>k ,geologic ,ye>s ago ,geologic ev5ts 9 ! area ( ! p>k "t scale 8,po/glacial0 ,pres5t summit cone ( ,m\nt ,ra9i] probably 0 built ab\t #b1jjj ye>s ago4 ,! la/ kn[n pumice eruption occurr$ betwe5 #ahbj & #ahed4 ,glaci]s />t$ to gr[ & advance ab\t #c1jjj ye>s ago4 ,maximum ext5ts 7 rea*$ ab\t #ahej ,a4,d4 ,f !n until ab\t #aiee1 glaci]s 7 rec$+2 n[ !y are 9 balance or advanc+4 ,huge masses ( rock h slid f ! volcano repeat$ly dur+ ! la/ #aj1jjj ye>s4 ,"o ( ^! de/roy$ ! summit ( ,m\nt ,ra9i] & =m$ ! ,osceola ,mudfl[ ab\t #e1hjj ye>s ago4 #aj1jjj ,plei/oc5e ,la/ major glaciation4 7,ice ,age7 #be1jjj ,bir? & gr[? ( ,m\nt ,ra9i] volcano1 & repeat$ glaciation4 #b-c million ,plioc5e ,uplift & erosion ( ! ,cascade ,range4 #ab million ,mioc5e ,intrusion ( granodiorite4 ,fold+ ( old] rocks4 ,deposition ( ,fifes ,peak & ,/ev5s ,ridge ,=mations4 #bf million ,oligoc5e ,deposition ( ,ohanapeco% ,=mation4 #cg-ch million ,eoc5e ,deposition ( ,puget ,gr\p4 #ec-ed million ,avalan*es & mudfl[s l ^? describ$ are normal ev5ts at ,m\nt ,ra9i] & are expect$ to happ5 aga9 9 ! future4 ,almo/ any cliff on ! volcano c produce a l>ge rockfall1 b :i* cliff w collapse next1 or :51 _c be pr$ict$4 ,%\ld ! volcano aga9 become active1 e>?quakes & volcanic explosions w\ld trigg] avalan*es & mudfl[s t w\ld ru% d[n ! m\nta94 ,molt5 rock w\ld melt sn[ & ice at ! volcano's summit & s5d floods ( wat] d[n ! volcano's flanks4 ,^! indirect effects ( an eruption w\ld be mu* m haz>d\s ?an lava fl[s & pumice1 if eruptions are on a scale simil> to t ( ! pa/ #aj1jjj ye>s4 ,! ,volcano's ,future8 ,an active volcano *anges cont9ually4 ,repeat$ eruptions build ! cone by pil+ "o lava fl[ on top ( o!rs1 or on top ( o!r volcanic =mations4 ,simultane\sly1 ! comb9$ processes ( erosion we> ! volcano d[n4 ,! relative importance ( ! two processes--"o build+1 ! o!r de/roy+--is reflect$ 9 ! volcano's %ape4 ,! sc>r$ & deeply g\g$ sides ( ,ra9i]'s cone %[ t erosion has be5 dom9ant "h = a long "t4 ,is ,m\nt ,ra9i] n[ doom$ to cont9u$ piecemeal de/ruction until ! l(ty cone is r$uc$ to a featureless m\nd8 ,w future eruptions ( lava re/ore "s ( ! volcano's bulk8 ,or w ! volcano erupt viol5tly "s day1 & !n collapse z did ,m\nt ,mazama to =m ! deep bas9 ( ,crat] ,lake8 ,! answ]s may n be kn[n = c5turies--or !y may appe> tomorr[4 ,fur!r ,read+ 9 ,geology ,cr&ell1 ,d4 ,r41 #aifi1 ,surficial geology ( ,m\nt ,ra9i] ,national ,p>k1 ,wa%+ton3 ,u4,s4 ,geological ,survey ,bullet9 #abhh4 ,a geologic map t %[s :]e glacial deposits1 l&slides1 & mudfl[s are locat$ 9 ! p>k is accompani$ by an illu/rat$ nonte*nical description ( ^! & o!r surficial deposits4 ,cr&ell1 ,d4 ,r41 & ,fahne/ock1 ,r4 ,k41 #aife1 ,rockfalls & avalan*es f ,little ,tahoma ,peak on ,m\nt ,ra9i]1 ,wa%+ton3 ,u4,s4 ,geological ,survey ,bullet9 #abba-;,a1 #cj pages4 ,a description ( ! sev5 successive l&slides ( ,decemb] #aifc t buri$ ! upp] ,:ite ,riv] valley "u ?ick deposits ( rock debris4 ,cr&ell1 ,d4 ,r41 & ,mull9eaux1 ,d4 ,r41 #aifg1 ,volcanic haz>ds at ,m\nt ,ra9i]1 ,wa%+ton3 ,u4,s4 ,geological ,survey ,bullet9 #abch1 #bf pages4 ,a discussion ( ,m\nt ,ra9i]'s eruptions dur+ ! la/ #aj1jjj ye>s & ! anticipat$ effects ( simil> future eruptions4 ,fiske1 ,r4 ,s41 ,hopson1 ,c4 ,a41 & ,wat]s1 ,a4 ,c41 #aifd1 ,geologic map & section ( ,m\nt ,ra9i] ,national ,p>k1 ,wa%+ton3 ,u4,s4 ,geological ,survey ,miscellane\s ,geologic ,inve/igations ,map ,i-#dcb1 ) text4 ,a geological map ( ! p>k's b$rock is accompani$ by a brief nonte*nical discussion ( ! geological evolution ( ! p>k z record$ by ! rock =mations4 ,sigafoos1 ,r4 ,s41 & ,h5dricks1 ,e4 ,l41 #aifa1 ,botanical evid5ce ( ! mod]n hi/ory ( ,nisqually ,glaci]1 ,wa%+ton3 ,u4,s4 ,geological ,survey ,pr(essional ,pap] #chg-;,a1 #bj pages4 ,a description ( ! rec5t mora9es ( sev]al glaci]s & an explanation ( h[ !y are dat$ by c\nt+ ! gr[? r+s ( trees gr[+ on !m4 ,u4,s4 ,,gov]nm5t ,,pr9t+ ,,(fice3 #aifh ,o--#cec-efj ,footnotes #a,! ,x pumice occurs z scatt]$ fragm5ts & does n =m a cont9u\s lay]4 #b;,ages ( m ?an #aej & less ?an #f1jjj ye>s cit$ 9 ?is report are bas$ on radioc>bon det]m9ations :i* h be5 correct$ by ! use ( a ,c half life ( #e1gcj ye>s & = v>iations 9 atmosph]ic ,c 7,h4 ,e4 ,suess1 writt5 communication to ,mey] ,rub91 #aifh74 #c;,= m in=mation ab\t glaci]s read 8,glaci]s0 by ,rob]t ,p4 ,%>p1 publi%$ 9 #aifj by ! ,univ]sity ( ,oregon at ,eug5e4 ,illu/ration3 ,,dep>tm5t ,,( ,,! ,,int]ior ,,m>* #c1 #ahdi ,transcrib]'s ,notes --,copyright notice provid$ z 9 ! orig9al--?is e-text is public doma9 9 ! c\ntry ( publication4 --,sil5tly correct$ palpable typos1 leav+ non-/&>d spell+s & dialect un*ang$4 --,only 9 ! text v]sions1 delimit$ italiciz$ text 7or non-italiciz$ text )9 poetry7 9 und]scores 7! ,,html v]sion reproduces ! font =m ( ! pr9t$ book47