,glaci]s & ,glaciation                  
9                           ,glaci]     
,national ,p>k                          
,price #ce ,c5ts        ,illu/ration3   
,,publi%$ ,,by ,,! ,,glaci] ,,natural   
,,hi/ory                                
,,association                   ,,9     
,,coop]ation ,,) ,,! ,,national ,,p>k   
,,s]vice        ,illu/ration3 ,,national
 ,,p>k ,,s]vice                         
,cov]           ,survey+ ,sp]ry         
,glaci]--,ar?ur ,johnson ( ,u4 ,s4 ,g4  
,s4                       ,n4 ,p4 ,s4   
,photo by ,j4 ,w4 ,corson               
,,revis$ #aiff                          
,,repr9t #aiga                          
,,?omas ,,pr9t+ #e,m#ga                 
,,glaci]s ,,& ,,glaciation ,,9 ,,glaci] 
,,national ,,p>k                        
,by                             ,james  
,l4 ,dyson#a                 ,head1     
,dep>tm5t ( ,geology & ,geography       
,lafayette ,college    ,! glaci]s (     
,glaci] ,national ,p>k are only a few ( 
_m ?\s&s  :i* occur 9 m\nta9 ranges     

scatt]$ ?r\gh\t ! _w4 ,glaci]s  occur 9 
all latitudes & on e cont95t except     
,au/ralia4 ,!y are  pres5t along !      
,equator on high volcanic peaks (       
,africa & 9 !  rugg$ ,&es ( ,s\?        
,am]ica4 ,ev5 9 ,new ,gu9ea1 :i* _m ?9k 
(  z a /eam+1 tropical jungle isl&1 a   
few small glaci]s occur on !  highe/    
m\nta9s4    ,almo/ ev]yone :o has made a
 trip to a high m\nta9 range has he>d  !
 t]m1 8sn[l9e10 & _m p]sons h us$ ! ^w  
)\t  kn[+ its real mean+4 ,! sn[l9e is !
 level above :i* m  sn[ falls 9 w9t] ?an
 c be melt$ or evaporat$ dur+ ! summ]4  
,on m\nta9s :i* rise above ! sn[l9e     
glaci]s usually occur4 ,!  sn[l9e is an 
elusive feature & c be se5 only 9 late  
summ]4 ,=  example1 dur+ ! latt] "p (   
,june sn[ ext5ds f ! summits (  mo/     
,glaci] ,national ,p>k m\nta9s d[n _!   
slopes to timb]l9e1  & "s sn[banks ext5d
 ev5 l[]4 ,at t "t ! sn[l9e appe>s  to  
be d[n ne> timb]l9e4 ,b z ! summ]       
progresses & high]  temp]atures melt !  
l[]-ly+ sn[banks ?is app>5t sn[l9e      

retreats high] & high] up ! slopes1     
until late ,augu/ or e>ly  ,septemb]1 :5
 x rea*es a po9t above :i* x w n        
retreat4 ,?is  l[] limit ( sn[ is !     
p]man5t or regional sn[l9e4 ,x is       
usually  ref]r$ to simply z ! sn[l9e4 ,9
 ,glaci] ,national ,p>k !  regional     
sn[l9e actually lies above ! summits (  
mo/ peaks1 at a  height ( m ?an #aj1jjj 
feet4 ,! only p>ts ( ! ,unit$ ,/ates    
s\? ( ,canada :i* project above ! sn[l9e
 are ! highe/ summits  9 ! ,cascade     
,range 9 ,cali=nia1 ,oregon1 & ,wa%+ton1
 & 9 !  ,olympic ,m\nta9s 9 ! latt]     
/ate4 ,!re are _m m\nta9s 9  ,alaska t  
lie above ! sn[l9e4 ,?is is especially  
true 9 !  coa/al ranges :]e ! sn[l9e is 
ar\nd #d1ejj feet above sea level4    ,!
 ,olympic area is unique1 = "h !        
regional sn[l9e desc5ds to  ab\t #f1jjj 
feet l[] ?an any:]e )9 ! b\nd>ies ( !   
,cont95tal ,unit$ ,/ates s\? ( ,alaska4 
,extraord9>ily heavy annual  sn[fall & !
 high p]c5tage ( cl\dy wea!r1 :i* ret>ds
 !  melt+ ( sn[1 comb9e to depress !    

sn[l9e to su* a l[ level4               
,glaci]s ( ,glaci] ,national ,p>k       
,)9 ! b\nd>ies ( ,glaci] ,national ,p>k 
!re are #ej to #fj  glaci]s1 ( :i* only 
two h surface areas ( ne>ly "o-half     
squ>e  mile1 & n m ?an sev5 o!rs exce$  
"o-f\r? squ>e mile 9  area4    ,all ^!  
bodies ( ice lie at ! heads ( valleys ) 
high /eep  headwalls on ! ea/ & nor?    
sides ( high ridges at elevations       
betwe5 #f1jjj & #i1jjj feet1 9 all cases
 well bel[ ! sn[l9e4  ,consequ5tly1 ^!  
glaci]s owe _! orig9 & exi/5ce almo/    
entirely to w9d-drift$ sn[4    ,ice )9  
^! glaci]s moves sl[ly4 ,! av]age rate 9
 ! smalle/  ones may be z l[ z #f to #h 
feet a ye>1 & 9 ! l>ge/ probably #be  to
 #cj feet a ye>4 ,!re is no p]iod ( !   
ye> :5 a glaci] is  motionless1 al?\gh  
movem5t is some:at sl[] 9 w9t] ?an 9    
summ]4 ,despite ! sl[ness ( its motion !
 ice1 ov] a p]iod (  ye>s1 transports   
l>ge quantities ( rock mat]ial          
ultimately to !  glaci]'s end :]e x is  
pil$ up 9 ! =m ( a mora9e4              

,illu/ration3 ,,front ,,( ,,sp]ry       
,,glaci]    ,! l>ge/ glaci] 9 ! ,p>k is 
,gr9nell4 ,9 #aifj x _h a surface  area 
( #cae acres4    ,sp]ry is ! second     
l>ge/ glaci] 9 ! ,p>k4 ,its surface 9   
#aifj  0 #bhg acres4 ,bo? ,gr9nell &    
,sp]ry h probable maximum  ?icknesses ( 
#djj to #ejj feet4        ,illu/ration3 
,,jackson ,,glaci] ,,is ,,visible ,,f   
,,go+-,,to-,,!-,,sun ,,road             
7,,beatty ,,photo7    ,o!r important    
,p>k glaci]s1 al?\gh mu* small] ?an !   
fir/ two  m5tion$1 are ,h>rison1 ,*aney1
 ,sexton1 ,jackson1 ,blackfoot1 ,siyeh1 
&  ,ah]n4 ,sev]al o!rs approa* "s ( ^! 9
 size1 b because (  isolat$ locations !y
 are seldom se54 ,z a matt] ( fact1 !re 
are  p]sons :o visit ,glaci] ,national  
,p>k )\t see+ a s+le glaci]1  :ile o!rs1
 al?\gh !y actually see glaci]s1 leave !
 p>k  )\t realiz+ !y h se5 !m4 ,?is is  
because ! highways  af=d only di/ant    
views ( ! glaci]s1 :i* f a di/ance appe>
  mu* l m]e accumulations ( sn[4 ,a     
notable example is ,gr9nell z  se5 f !  

highway along ! %ore ( ,%]burne ,lake & 
f !  vic9ity ( ! ,_m ,glaci] ,entrance  
,/ation4 ,! glaci]1 despite its  l5g? ( 
almo/ a mile1 appe>s m]ely z a          
conspicu\s :ite pat*  high up on ! ,g>d5
 ,wall at ! head ( ! valley4    ,sev]al 
( ! glaci]s1 h[ev]1 are accessible by   
trail & are  annually visit$ by _m      
hundr$s ( p1 ei!r on foot or by horse4  
,mo/ accessible ( all ,p>k glaci]s is   
,gr9nell4 ,x c be rea*$ by a  six-mile  
trip ov] an excell5t trail f ,_m ,glaci]
 ,hotel or  ,swiftcurr5t ,camp4 ,sp]ry1 
likewise1 c be rea*$ by trail1 al?\gh  !
 di/ance is sev]al miles great] ?an 9 ! 
case ( ,gr9nell4 ,!  trip1 h[ev]1 c be  
brok5 & possibly made m int]e/+ by an   
ov]night /op at ,sp]ry ,*alet1 :i* is   
locat$ ab\t ?ree miles f  ! glaci]4     
,siyeh is ! only o!r regul>ly visit$    
,p>k glaci]4 ,x  lies ab\t half a mile  
beyond ! end ( ! ,crack] ,lake trail1 & 
c  be rea*$ f t po9t by an easy walk    
?r\gh grassy mead[s & a  %ort climb ov] 
a mora9e4 ,siyeh1 h[ev]1 is less        

spectacul> ?an  ei!r ,gr9nell or ,sp]ry1
 be+ mu* small] & lack+ crevasses1 s    
common on ! o!r two4 ,few p make !      
spectacul> trail trip ov]  ,siyeh ,pass 
b ^? :o d may visit ,sexton ,glaci] by  
mak+ a %ort  det\r ( less ?an half a    
mile :]e ! trail crosses ! b5* on  :i* !
 glaci] lies4 ,sexton is a small glaci]1
 b late 9 !  summ] aft] its sn[ cov] has
 melt$ (f x exhibits _m ( !  features   
se5 on mu* l>g] bodies ( ice4           
,int]e/+ surface features :i* c be se5  
at times on any ( ^!  glaci]s include   
crevasses1 m\l9s 7glaci] wells71 debris 
cones1 &  glaci] tables4 ,crevasses are 
cracks :i* occur 9 ! ice ( all  glaci]s4
 ,!y are especially num]\s on ,sp]ry &  
,gr9nell4 ,m\l9s1  or glaci] wells1 are 
deep v]tical holes :i* h be5 =m$ by a   
/ream ( wat] :i* orig9ally plung$ into a
 n>r[ crevasse4  ,cont9ual fl[ ( ! /ream
 enl>ges t "p ( ! crevasse1  creat+ a   
well4 ,sev]al su* features on ,sp]ry    
,glaci] h p5etrat$  to dep?s ( m ?an    
#bjj feet1 & are #bj or m feet wide at !

  top4    ,no "o c walk ov] ! surface ( 
,gr9nell ,glaci] )\t notic+ a  numb] (  
conical m\nds ( f9e rock debris4        
,actually ^! are cones  ( ice cov]$ ) a 
v5e]1 seldom m ?an two in*es ?ick1 (    
rock  debris1 s _! "n1 debris cone is   
some:at mislead+4        ,illu/ration3  
,,crevasse ,,9 ,,sp]ry ,,glaci]    ,?is 
rock mat]ial1 usually deposit$ by a     
/ream1 protects ! ice  und]nea? f !     
sun's rays4 ,z ! surface ( ! glaci]1    
except  t insulat$ by ! debris1 is l[]$ 
by melt+1 ! m\nds =m &  gr[ gradually   
high] until ! debris slides f !m1 aft]  
:i*  !y are spe$ily r$uc$ to ! level ( !
 re/ ( ! surface4 ,!y  are seldom high] 
?an #c or #d feet4    ,a glaci] table is
 a m\nd ( ice capp$1 & !re=e protect$ f 
melt+1 by a l>ge b\ld]4 ,its hi/ory is  
simil> to t ( !  debris cone4 ,aft] a "t
 ! b\ld] slides (f its p]*1 & !n !  m\nd
 ( ice melts away4    ,sn[ :i* fills    
crevasses & wells dur+ ! w9t] (t5 melts 
out  f bel[1 leav+ ?9 sn[bridges 9 !    
e>ly "p ( ! summ]4  ,^! con/itute real  

haz>ds to travel on a glaci] because !  
?9n]  ones are incapable ( support+ a   
p]son's weight4 ,?is is "o v  good      
reason :y ! inexp]i5c$ %\ld nev] v5ture 
onto ! surface  ( a glaci] )\t a guide4 
,x is probable t ! ,p>k glaci]s are n   
remnants ( ! l>ge  glaci]s pres5t dur+ !
 ,ice ,age :i* t]m9at$ approximately    
#aj1jjj ye>s ago1 because x is kn[n t   
sev]al ?\s& ye>s aft]  t "t ! climate ( 
! ,glaci] ,national ,p>k region 0       
some:at  dri] & w>m] ?an n[4 ,"u su*    
conditions x is probable t  mo/1 if n   
all1 ( ! pres5t glaci]s c\ld n h exi/$4 
,%r9kage ( ,p>k ,glaci]s      ,prior to 
! beg9n+ ( ! pres5t c5tury all glaci]s 9
 ! ,p>k1  & mo/ ( ^? 9 ! re/ ( ! _w1    
began to %r9k 9 response  to a slight   
*ange 9 climate1 probably involv+ bo? a 
temp]ature  rise & a decrease 9 annual  
sn[fall4 ,f ab\t #aijj to #aide  %r9kage
 ( ,p>k glaci]s 0 v rapid4 ,9 o!r words 
^! glaci]s  7 n 9 equilibrium ) !       
climate1 = less ice 0 add$ to !m  ea*   
w9t] ?an disappe>$ by melt+ &           

evaporation dur+ !  rema9d] ( ! ye>4    
,ov] a p]iod ( sev]al ye>s su* %r9kage  
is app>5t to ! eye (  an obs]v] & is    
manife/ by a l[]+ ( ! glaci]'s surface1 
&  m p>ticul>ly by a 8retreat0 ( ! l[]  
edge ( ! glaci]4 ,?is  "p ( ! ice is    
g5]ally ref]r$ to z ! ice front4 ,:5    
suffici5t sn[ is add$ to ! upp] "p ( !  
glaci] to cause !  ice at ! front to    
move =w>d equal to ! rate at :i* x melts
  away1 ! glaci] is 9 equilibrium ) !   
climate4 ,:5 ! ye>ly  add$ sn[ decreases
 9 am\nt ! ice front seems to retreat or
 move  back1 :]eas ! mass ( ! glaci] is 
m]ely decreas+ by melt+ on  top & along 
! edges1 j z a cube ( ice left 9 ! kit*5
 s9k  decreases 9 size4    ,! ,national 
,p>k ,s]vice initiat$ obs]vations on    
glaci] v>iations  9 #aica4 ,at fir/ ! "w
 consi/$ only ( ! det]m9ation ( !  ye>  
by ye> *anges 9 ! ice front ( ea* ( !   
sev]al glaci]s4  ,f #aicg to #aici1     
inclusive1 ! program 0 exp&$ to include 
!  detail$ mapp+ ( ,gr9nell1 ,sp]ry1 &  
,jackson ,glaci]s to s]ve z a  basis =  

comp>isons 9 future ye>s4 ,a]ial        
photographs 7 obta9$  ( all ! kn[n ,p>k 
glaci]s 9 #aiej & #aieb & aga9 9 #aifj4 
,maps  h be5 compil$ & publi%$ ( !      
,gr9nell & ,sp]ry ,glaci]s  bas$ on !   
#aiej & #aifj a]ial photography4 ,!     
#aiej & #aifj maps (  ea* glaci] are %[n
 on "o %eet = conv5i5ce 9 comp>ison4    
,s9ce #aide1 ! glaci] obs]vations h be5 
c>ri$ on 9 coop]ation  ) ! ,u4 ,s4      
,geological ,survey4 ,! "w has includ$ !
 p]iodic  measurem5t ( pr(iles to       
det]m9e *anges occurr+ 9 ! surface      
elevation ( ,gr9nell & ,sp]ry ,glaci]s &
 also ! det]m9ation (  ! rate ( annual  
movem5t4 ,"s ( ! m important data yield$
 by  surveys on ,gr9nell & ,sp]ry1 ! two
 l>ge/ glaci]s 9 ! ,p>k1  are summ>iz$ 9
 ! foll[+ tabulations3                  
,,gr9nell ,,glaci]   ,ye>   ,area       
,rem>ks         7,acres7     #aija  #ebe
     ,f ,*ief ,m\nta9 topographic       
quadrangle map4   #aicg  #chd     ,f    
mapp+ by ,j4 ,l4 ,dyson & ,gibson ( l[] 
portion                 ( glaci] plus   

area ( upp] glaci] 7#ef acres71 z       
%[n on #aiej ,,usgs map4   #aidf  #ccf  
,z above4   #aiej  #cbh     ,f ,,usgs   
map compil$ f a]ial photography4   #aifj
  #cae     ,z above4    ,! ,gr9nell     
,glaci] orig9ally consi/$ ( an upp] &   
l[] portion  connect$ by an ice tongue4 
,?is tongue disappe>$ 9 #aibf & s9ce  !n
 ! two portions h be5 sep>ate4 ,! area (
 ! upp] portion  ( ! glaci] 0 ess5tially
 ! same 9 #aifj z 9 #aief--ef acres4 ,! 
upp] section is kn[n z ,salam&] ,glaci] 
because ( its %ape z  view$ f a di/ance4
    ,! t]m9al recession ( ! ,gr9nell    
,glaci] is some:at difficult to  det]m9e
 accurately z a "p ( ! t]m9al portion   
ends 9 a lake1  ! %ore ( :i* v>ies f ye>
 to ye>4 ,! recession = a  half-mile    
section ext5d+ s\!a/ f ! lake is %[n    
bel[3       ,p]iod    ,recession dur+   
,total ,recession      ,av]age annual   
p]iod 7feet7     s9ce #aicg 7feet7      
recession 7feet7      #aicg-de          
#bgj                 #bgj               
#cd    #aide-ej           #ge           

#cde                  #ae    #aiej-fj   
#he                 #dcj                
#h    ,! values = area & recession %[n  
above indicate t *anges 9  ! area ( !   
glaci] h n be5 z pron\nc$ s9ce !        
mid-#aidj's  z !y 7 prior to t "t4      
,pr(ile measurem5ts />t+ 9 #aiej        
indicate a g5]al tr5d ( cont9u$ %r9kage 
al?\gh annual *anges  h be5 bo? positive
 & negative4 ,! #aife obs]vations %[$ a 
surface l[]+ ( #bj to #be feet1 s9ce    
#aiej4    ,! movem5t ( ! ,gr9nell       
,glaci]1 bas$ on obs]vations s9ce #aidg1
  has be5 ab\t #ce to #dj feet p] ye>4  
,! ,sp]ry ,glaci] is locat$ #i miles f !
 ,gr9nell ,glaci]1 on !  opposite side (
 ! ,cont95tal ,divide & at an altitude  
approximately  #a1jjj feet high]4 ,x has
 also %[n a cont9ual %r9kage 9 area &   
recession ( ! t]m9us z %[n by ! foll[+  
tabulations3                            
,,sp]ry ,,glaci]   ,ye>   ,area         
,rem>ks         7,acres7     #aija  #haj
     ,f ,*ief ,m\nta9 topographic       
quadrangle map4   #aich  #cij     ,f    

mapp+ by ,j4 ,l4 ,dyson & ,gibson4      
#aidf  #ccj     ,f mapp+ by ,j4 ,l4     
,dyson4   #aiej  #cje     ,f ,,usgs map 
compil$ f a]ial photography4   #aifj    
#bhg     ,f ,,usgs map compil$ f a]ial  
photography4    ,recession1 9 feet1 (   
c5tral half-mile section ( t]m9us       
,p]iod       ,recession        ,total   
recession      ,av]age annual           
s9ce #aich          recession           
#aich-de          #cea                  
#cea                  #ej    #aide-ej   
#agg                 #ebh               
#ce    #aiej-fj          #bdd           
#gib                  #bd    ,pr(ile    
measurem5ts1 />t+ 9 #aidi1 indicate a   
cont9u$ l[]+ (  ! glaci] surface bel[ an
 altitude ( ab\t #g1ejj feet4 ,above ?is
  altitude x has rema9$ mu* ! same dur+ 
! p]iod ( obs]vations  ) annual *anges1 
bo? positive & negative1 ) a possible   
slight  net increase s9ce #aidi4    ,!  
=w>d movem5t 9 ! c5tral portion ( !     
,sp]ry ,glaci]1 bas$  on obs]vations    
s9ce #aidi1 has av]ag$ ab\t #ae feet p] 

ye>4 ,!  rate ( movem5t is presum$ to be
 great] 9 ! upp] rea*es ( !  glaci]4    
,x is ( int]e/ to note f ! data t !     
*anges 9 ,sp]ry  ,glaci] are m pron\nc$ 
?an ^? 9 ,gr9nell ,glaci] al?\gh !      
/raight-l9e di/ance betwe5 !m is only #i
 miles4 ,"o possible  reason--,gr9nell  
,glaci] is on ! ea/]n slope ( !         
,cont95tal  ,divide :]eas ,sp]ry ,glaci]
 is on ! we/]n slope4    ,ev5 m         
significant is ! l[]+ ( ! glaci]'s      
surface1 f  :i* volume %r9kage may be   
obta9$4 ,9 #aich ,sp]ry ,glaci] _h a    
?ickness ( #ajh feet at ! site ( ! #aidf
 ice m>g94 ,at ?is same  place 9 #aiac !
 ?ickness 0 ne>ly #ejj feet1 & ! av]age 
?ickness ( ! glaci] ov] ! area f :i* x  
has s9ce  disappe>$ 0 at lea/ #cjj feet4
    ,! av]age ?ickness ( ,gr9nell       
,glaci] 9 #aicg at ! site ( !  #aidf ice
 front 0 #gc feet4 ,! surface ( ! entire
 glaci] 0  l[]$ #ef feet dur+ t n9e-ye> 
p]iod4 ,?is means t ea* ye>  ! glaci] 0 
r$uc$ 9 volume by an am\nt ( ice        
equival5t to a  cube #dej feet high4    

,illu/ration3 ,,gr9nell ,,glaci] ,,z ,,x
 ,,look$ ,,prior ,,to #aibf ,,:5 ,,!    
,,l[] ,,& ,,upp] ,,segm5ts ,,7 ,,/ill   
,,connect$4    ,at ! nor!rn t]m9us (    
,gr9nell ,glaci]1 :i* is bord]$ by a    
small m>g9al lake1 a l>ge section ( !   
ice front fell into !  wat] on or ab\t  
,augu/ #ad1 #aidf1 completely fill+ x ) 
iceb]gs4  ,?is ev5t1 al?\gh witness$ by 
no "o1 mu/ h be5 comp>able to  _m ( !   
icefalls :i* occur at ! fronts ( ! l>ge 
glaci]s  along ! s\!a/ coa/ ( ,alaska4  
,! volume ( ,gr9nell ,glaci] 0 r$uc$ by 
ab\t "o-?ird f  ,septemb] #aicg to      
,septemb] #aidf4 ,sev]al o!r glaci]s h  
exhibit$  a m ph5om5al %r9kage ?an      
,sp]ry or ,gr9nell4 ,! topographic map  
( ,glaci] ,national ,p>k1 prep>$ 9      
#aijj-aijb1 %[s sev]al  comp>atively    
l>ge glaci]s su* z ,agassiz1 ,blackfoot 
& ,h>rison4  ,_! %r9kage has be5 s      
pron\nc$ t today ,agassiz has virtually 
disappe>$ & ! o!r two are pitifully     
small remnants1 probably  less ?an      
"o-fif? ! size !y _h be5 :5 orig9ally   

mapp$4    ,s9ce #aide1 because (        
above-normal sn[fall & subnormal        
temp]atures1  glaci] %r9kage has sl[$   
d[n appreciably1 com+ virtually to a    
/&/ill 9 #aiej2 & 9 #aiea1 = ! fir/ "t  
s9ce glaci]  *anges h be5 record$ 9 !   
,p>k1 ,gr9nell ,glaci] increas$         
slightly 9 volume4 ,?is 0 also reflect$ 
by a readvance ( ! front4  ,al?\gh no   
measurem5ts 7 made 9 #aiea on o!r ,p>k  
glaci]s "s  ( !m c]ta9ly made simil>    
readvances4 ,?us ! climatic conditions  
:i* caus$ glaci]s to %r9k = fifty or m  
ye>s seem to h  be5 replac$ by          
conditions m favorable to ! glaci]s4 ,"t
 alone  w tell :e!r ! new conditions are
 tempor>y or m>k ! beg9n+  ( a long     
cycle ( wett] & cool] climate4          
,=m] ,ext5t ( ,p>k ,glaciation          
,dur+ ! ,plei/oc5e ,p]iod or ,ice ,age  
:5 mo/ ( ,canada & a l>ge  portion ( !  
,unit$ ,/ates 7 cov]$ sev]al times by an
 ext5sive  ice %eet or cont95tal glaci]1
 all ! valleys ( ,glaci] ,national  ,p>k
 7 fill$ ) valley glaci]s4 ,^! orig9at$ 

9 ! high]  p>ts ( ! ,lewis & ,liv+/one  
,ranges4 ,on ! ea/ side ( ! ,lewis      
,range !y mov$ out onto ! pla9s4 ,f !   
,liv+/one ,range & !  we/ side ( !      
,lewis ,range !y mov$ into ! wide       
,fla!ad ,valley4  ,dur+ ! maximum ext5t 
( ^! glaci]s all ( ! area ( ! ,p>k      
except ! summits ( ! highe/ peaks &     
ridges 7 cov]$ )  ice4    ,! great ,two 
,m$ic9e ,glaci]1 ) its s\rce 9 ! head ( 
! ,two  ,m$ic9e & tribut>y valleys1 aft]
 rea*+ ! pla9s spread out  into a big   
lobe 7pi$mont glaci]7 ev5tually atta9+ a
 di/ance (  ab\t #dj miles f ! ea/]n    
front ( ! m\nta9s4 ,! /ream (  ice em]g+
 onto ! pla9s f ,/4 ,m>y ,valley also   
ext5d$ _m  miles out f ! m\nta9 front4  
,sev]al ( ^! long valley glaci]s  ext5d$
 f> en\gh out onto ! pla9s to meet !    
edge ( ! va/  cont95tal ice %eet mov+   
we/w>d f a c5t] 9 ! vic9ity (  ,hudson  
,bay4 ,9 ! major ,p>k valleys ^! glaci]s
 atta9$  ?icknesses ( #c1jjj or m feet4 
,al?\gh man probably nev] view$  ?is    
magnific5t spectacle1 ! ,p>k at t "t mu/

 h be5 simil>  9 aspect to "s ( ! pres5t
 day ice fill$ ranges along !           
,alaska-,yukon bord]4    ,no "o kn[s    
exactly h[ _m times glaci]s mov$ d[n !  
,p>k valleys  dur+ ! million or m ye>s (
 ! ,plei/oc5e p]iod1 b  geologi/s h f\nd
 evid5ce = at lea/ eight di/9ct         
advances4 ,x  is difficult to det]m9e j 
:5 ! fir/ advance took place b x  may h 
be5 v e>ly 9 ! p]iod4 ,mo/ ( ! advances1
 h[ev]1  occurr$ dur+ ! pa/ #gj1jjj ye>s
 or s 9 :at is kn[n z !  ,wiscons9 /age 
( ! ,ice ,age4 ,l>ge glaci]s fl[$ d[n ! 
,p>k  valleys probably z late z #g1jjj  
ye>s ago4 ,betwe5 ea* ( ! major  times (
 ice advance1 ! glaci]s1 respond+ to    
w>m] or dri]  climate1 %rank to small   
size & 9 "s in/ances disappe>$4 ,^!     
w>m] int]vals v>i$ 9 l5g? f #b1jjj to   
t5s ( ?\s&s (  ye>s4    ,evid5ce ( !    
sev]al di/9ct glacial advances is yield$
 by !  mora9es1 deposits ( rock debris  
left by ! ice4 ,on ! ea/ side (  ! ,p>k 
! l[] c\rses ( ! major valleys & !      
adjo9+ ridges  9 ! ,p>k & on ! adjac5t  

pla9s are cov]$ ) mora9es4 ,!  mat]ial 9
 !m ranges 9 size f clay to l>ge b\ld]s1
 & 0  deposit$ by glaci]s aft] be+      
transport$ d[n ! valleys4 ,!  debris    
deposit$ by ! late/ ice advance is fre% 
9 appe>ance &  conta9s fragm5ts ( all   
,p>k rocks4 ,mora9es ( ! e>li] /ages1   
because ( mu* great] age1 are m wea!r$4 
,!y conta9 _m  fragm5ts ( mu* wea!r$    
diorite1 f ! lay] ( rock t appe>s  z a  
conspicu\s black b& on _m ( ! m\nta9s1 &
 almo/ no  fragm5ts ( lime/one1 s common
 9 ! newe/ mora9es4 ,! diorite is  m    
resi/ant to wea!r+ ?an ! lime/one :i*   
sl[ly dissolves  9 gr\nd-wat]4 ,! only  
localities :]e ! olde/ mora9e occurs are
  ! cre/s ( ! ridges :i* run ea/w>d f ! 
m\nta9s out onto  ! pla9s4 ,?is mat]ial 
is especially abundant on ,/4 ,m>y      
,ridge4 ,on  top ( ,two ,m$ic9e ,ridge  
along & j above ! highway1 fragm5ts (   
?is mat]ial h be5 cem5t$ toge!r into a  
comp>atively h>d  tillite4 ,l[] d[n on !
 slopes ! old] mora9e _c be f\nd z  x is
 cov]$ by t ( ! lat] glacial advances   

:i* 7 less  ext5sive & did n ov]ride !  
ridge cre/s z did ! e>li]  glaci]s4 ,!  
old] debris is also f\nd on top ( ,milk 
,riv] &  ,b\ld] ,ridges4    ,foll[+ !   
la/ maximum advance ( ! ,wiscons9       
glaci]s !y sl[ly  %rank until ab\t      
#f1jjj ye>s ago :5 all glacial ice      
probably  disappe>$ f ! m\nta9s4 ,aft]  
?is !re 0 a w>m1 dry p]iod  dur+ :i* x  
is probable t no glaci]s 7 pres5t4 ,!n  
ab\t  #d1jjj ye>s ago ! pres5t small    
glaci]s 7 born4 ,dur+ ! p]iod  ( _!     
exi/5ce !y h fluctuat$ 9 size1 probably 
atta9+  maximum dim5sions ar\nd ! middle
 ( ! la/ c5tury4 ,s9ce !n  !y h be5     
gett+ small]4        ,illu/ration3      
,,panoramic ,,view ,,( ,,gr9nell        
,,glaci] ,,z ,,x ,,appe>$ ,,9           
#aide4 ,,! ,,crevasses ,,9 ,,glaci]     
,,may ,,be ,,ov] #ej ,,feet ,,deep      
7,,beatty      ,,photo7                 
,illu/ration3 ,,panoramic ,,view ,,(    
,,sp]ry ,,glaci] ,,z ,,x ,,appe>$ ,,9   
#aidf4 ,,note ,,melt-,,wat] ,,lakes     
,,t]m9at+ ,,aga9/ ,,mora9es ,,at        

,,extreme      ,,left 7,,dyson ,,photo7 
,p>k ,features ,result+ ,f ,glaciation  
,a glaci] is an extremely p[]ful ag5t ( 
erosion1 capable (  pr(\ndly alt]+ !    
l&scape ov] :i* x passes4    ,glaci]s   
erode ma9ly by two processes1 pluck+ &  
abrasion4 ,! fir/  is m active ne> !    
head ( ! glaci]1 b may take place any:]e
  ?r\gh\t its c\rse2 abrasion or sc\r+  
is effective und]nea? mo/  sections ( ! 
glaci]1 p>ticul>ly :]e ! ice moves 9 a  
well-def9$ *annel4        ,illu/ration3 
,,mt4 ,,ob]l9 ,,cirque ,,& ,,bird       
,,woman ,,falls 7,,hileman      ,,photo7
    ,9 pluck+1 ! glaci] actually qu>ries
 out masses ( rock1  incorporates !m )9 
itself1 & c>ries !m along4 ,at ! head ( 
! glaci] ?is is accompli%$ ma9ly by wat]
 :i* trickles into  crevices & freezes  
ar\nd blocks ( rock1 caus+ !m to be     
pull$  out by ! glaci]1 & also by !     
weight ( ! glaci]1 squeez+ ice  into !  
cracks 9 ! rock4 ,z ! glaci] moves =w>d 
^! blocks  ( ice are dragg$ or c>ri$    
along ) x4 ,usually a l>ge crevasse1  ! 

b]gs*rund1 develops 9 ! ice at ! head ( 
a glaci]4 ,!  b]gs*rund ( mo/ glaci]s 9 
! p>k consi/s ( an op5+1 usually  #aj to
 #bj feet wide at ! top & z mu* z #ej   
feet deep1 betwe5 !  head ( ! glaci] & !
 m\nta9 wall4 ,on ,sp]ry ,glaci]1 h[ev]1
  x is m typical ( t f\nd on l>g] valley
 glaci]s & consi/s  ( sev]al conspicu\s 
crevasses sep>at+ ! firn area 7:]e !    
sn[ is compact$ into ice7 on top (      
,gunsight ,m\nta9 f ! glaci]  prop] bel[
 7see photo on ! cov]74 ,x is at ?is    
site t pluck+  is mo/ dom9ant because   
wat] ent]s by day & freezes 9 ! rock    
crevices at night4 ,?is qu>ry+ headw>d &
 d[nw>d f9ally results  9 ! =mation ( a 
/eep-sid$ bas9 call$ a cirque or glacial
  amphi!atre4 ,because ! cirque is !    
fir/ place t ice =ms &  ! place f :i* x 
disappe>s la/1 x is subject$ to glacial 
erosion long] ?an any o!r "p ( ! valley4
 ,?us its floor is  frequ5tly pluck$ &  
scrap$ out to a comp>atively great dep? 
s  t a body ( wat] kn[n z a cirque lake 
=ms aft] ! glaci]  disappe>s4 ,iceb]g   

,lake lies 9 "o ( ! mo/ magnific5t      
cirques 9  ! ,p>k4 ,! l[e/ po9t on !    
cre/ ( ! wall encircl+ ?ree  sides ( !  
lake is m ?an #aejj feet above ! wat]4  
,prior to #aidj  ?is cirque conta9$ a   
small glaci]4 ,x has be5 %r9k+ rapidly =
  ab\t two decades1 & 9 ! la/ two or    
?ree ye>s ( its exi/5ce  0 h>dly        
recognizable z a glaci]4 ,its           
disappe>ance is made m  rem>kable by ! k
 t 9 #aibj ! front ( ! glaci] rose  9 a 
%e] wall ( ice ne>ly #ajj feet above !  
surface ( ! lake4  ,all t rema9s ( ?is  
glaci] :i* once kept ! lake fill$ )     
iceb]gs ea* summ] is a l>ge bank ( sn[  
at ! base ( ! cirque  wall at ! head ( !
 lake4 ,o!r good examples ( cirques are 
^?  :i* hold ,hidd51 ,avalan*e & ,crack]
 ,lakes4 ,! trem5d\s cliff on  ! s\?    
side ( ! latt] rises #d1ajj feet f !    
lake to !  summit ( ,m\nt ,siyeh4 ,o!r  
notable cirque lakes are ,ell5 ,wilson1 
,gunsight1 ,pt>migan & ,upp] ,two       
,m$ic9e4        ,illu/ration3 ,,/4 ,,m>y
 ,,valley ,,f ,,logan ,,pass ,,%[+      

,,glacial      ,,pr(ile 7,,hileman      
,,photo7    ,rock fragm5ts ( v>i\s sizes
 froz5 into ! bottom & sides ( !  ice =m
 a huge file or rasp :i* abrades or we>s
 away ! bottom &  sides ( ! valley d[n  
:i* ! glaci] fl[s4 ,! valley ?us  atta9s
 a *>act]i/ic ,u-%ap$ cross section1 )  
/eep sides 7n  necess>ily v]tical7 & a  
broad bottom4 ,a m\nta9 valley cut      
entirely  by a /ream does n h su* %ape  
because ! /ream cuts only 9 !  bottom ( 
! valley1 :]eas a glaci]1 fill+ its     
valley to a great  dep?1 abrades along !
 sides z well z on ! floor4 ,practically
 all  valleys ( ! ,p>k1 especially !    
major ones1 possess ! ,u-%ap$  cross    
section4 ,?is feature c be/ be se5 by   
look+ d[n f !  head ( ! valley r ?an f !
 valley floor4 ,spl5did examples  are ! 
,swiftcurr5t ,valley view$ f            
,swiftcurr5t ,pass or ,look\t2  ,/4 ,m>y
 ,valley f ea/ ( ,logan ,pass2 ! ,belly 
,riv] ,valley f  ,pt>migan ,tunnel2 &   
,cat>act ,creek ,valley f ,gr9nell      
,glaci]4        ,illu/ration3 ,,figure  

#a4 ,,idealiz$ ,,sket* ,,( ,a ,,glacial 
,,/airway ,,f      ,,! ,,arete ,,at ,,! 
,,c5t] ,,( ,,! ,,range ,,to ,,! ,,ice   
,,age ,,mora9e ,,at ,,!      ,,m\? ,,(  
,,! ,,valley4      ,cirque wall         
,glaci]    ,lake    ,mora9e    ,! floors
 ( _m ( ! ,p>k's major ,u-%ap$ valleys  
in/ead (  hav+ a m or less uni=m slope1 
/eep] ne> ! head ?an f>!r  d[n1 z is    
usually ! case 9 a normal /ream valley1 
are m>k$ by  sev]al /eep drops or       
8/eps10 betwe5 :i* ! valley floor has a 
comp>atively g5tle slope4 ,su* a valley 
floor1 ?r\gh\t its entire  c\rse1 is    
sometimes t]m$ ! glacial /airway4 ,mo/ (
 ! /eps1  p>ticul>ly ^? 9 ! l[] c\rses (
 ! valleys1 are due to  diff]5ces 9     
resi/ance ( ! rocks ov] :i* ! =m] ice   
fl[$4  ,on ! ea/ side ( ! ,lewis ,range1
 :]e ! /eps are especially  pron\nc$1 ! 
rock /rata ( :i* ! m\nta9s are compos$  
dip  t[>d ! s\?we/1 directly opposite to
 ! direction ( ! slope (  ! valley      
floors 7,figure #a74 ,?us1 z glaci]s    
fl[$ f ! c5t]  ( ! range d[n t[>d !     

pla9s1 !y cut across ! edges ( ^!  tilt$
 rock lay]s2 :]e ! ice fl[$ ov] weak]   
b$s x 0 able to  sc\r out ! valley floor
 m deeply creat+ a 8tread0 ( ! glacial  
/airway4 ,! m resi/ant rock =mations 7  
less easily remov$1  & ! ice /ream1 9   
mov+ away f ! edges ( ^! resi/ant       
/rata1 employ$ its p[]s ( pluck+ &      
qu>ry+ to give rise to  cliffs or       
8ris]s40 ,lakes damm$ p>tly by !        
resi/ant rock /rata n[  fill depressions
 sc\r$ out ( ! weak] rock on ! treads   
7,figure #a  74 ,^! are rock-bas9 lakes1
 & :]e sev]al ( !m are /rung out  along 
! c\rse ( ! valley !y are ref]r$ to z   
pat]no/] lakes  because _! arrangem5t   
resembles t ( beads on a /r+4           
,well-kn[n examples ( su* bodies ( wat] 
are ,swiftcurr5t &  ,bullhead ,lakes1   
two ( ! long s]ies :i* /ret*es = sev5   
miles  betwe5 ,_m ,glaci] ,hotel &      
,swiftcurr5t ,pass4 ,resi/ant lay]s 9  !
 l[] portion ( ! ,altyn =mation1 ! upp] 
"p ( !  ,appekunny1 & ! upp] "p ( !     
,gr9nell#b normally create ris]s4       

,illu/ration3 ,,typical ,,glacial       
,,valley ,,) ,,*a9 ,,( ,,rock-,,bas9    
,,lakes4 ,,gl5n ,,& ,,crossley ,,lakes  
,,9 ,,di/ance2 ,,unnam$ ,,lake ,,9      
,,=egr\nd ,,re/s ,,9 ,a ,,hang+ ,,valley
 ,,& ,,its ,,outlet ,,drops ,,sev]al    
,,hundr$ ,,feet ,,to ,,! ,,ma9 ,,valley 
7,,hileman ,,photo7    ,! tribut>ies (  
glacial valleys are also peculi> 9 t !y 
usually ent] ! ma9 valley high above its
 floor & = ?is reason  are kn[n z hang+ 
valleys4 ,! ?ick] a /ream ( ice1 ! m    
erosion x is capable ( p]=m+2           
consequ5tly1 ! ma9 valley  becomes      
greatly deep5$1 :]eas ! small] glaci] 9 
! tribut>y  valley does n cut d[n s     
rapidly1 leav+ its valley hang+ high    
above ! floor ( ! major valley4 ,!      
valleys ( ,virg9ia &  ,flor5ce ,creeks1 
tribut>y to ! ,/4 ,m>y ,valley are      
excell5t examples  ( hang+ valleys4 ,a  
spl5did view ( ,virg9ia ,creek valley   
may be _h  f ,go+-to-!-,sun ,road ne> ! 
head ( ,/4 ,m>y ,lake4 ,! valley  above 
,bird ,woman ,falls z se5 f             

,go+-to-!-,sun ,road j we/ (  ,logan    
,pass is a spectacul> illu/ration ( a   
hang+ valley4 ,9  addition !re are _m   
o!rs1 su* z ,pre/on ,p>k1 on ! trail f  
,/4 ,m>y to ,piegan ,pass2 & ! ,hang+   
,g>d5s ne> ,logan ,pass4                
,illu/ration3 ,,reynolds ,,m\nta9 ,,at  
,,logan ,,pass--,a ,,typical ,,horn     
,ev5 m conspicu\s ?an ! l>ge ,u-%ap$    
valleys & _! hang+  tribut>ies are !    
long1 %>p-cre/$1 jagg$ ridges :i* =m mo/
  ( ! backbone ( ! ,lewis ,range4 ,^!   
features ( :i* ! ,g>d5  ,wall is "o ( ! 
mo/ noticeable1 are kn[n z aretes & owe 
_!  orig9 to glaci]s4 ,z ! =m] long     
valley glaci]s enl>g$ _!  cirques by    
cutt+ f>!r 9 t[>d ! c5t] ( ! range1 !   
latt]  f9ally 0 r$uc$ to a v n>r[       
/eep-sid$ ridge1 ! arete4 ,!  impos+    
height ( ! ,g>d5 ,wall c readily be     
det]m9$ by us+  ! lay] ( diorite z a    
scale4 ,! conspicu\s black b& =m$ by  ! 
edge ( ?is lay] has an av]age wid? ( #ge
 feet4 ,s1 f !  por* ( ! ,_m ,glaci]    
,hotel a ,p>k visitor c readily see t ! 

,g>d5 ,wall1 ev5 ?\gh five miles di/ant1
 is ab\t #d1bjj feet high4  ,! height ( 
o!r aretes c be j z readily obta9$1 = ! 
b&  ( diorite appe>s on ! faces ( mo/ ( 
!m4 ,9 c]ta9 places  glaci]s on opposite
 sides ( ! arete ne>ly cut ?r\gh creat+ 
a  l[ place kn[n z a col1 usually call$ 
a pass4 ,gunsight1 ,logan1 ,r$  ,eagle1 
,/oney ,indian & ,piegan are only a few 
( ! _m su* passes  9 ! ,p>k4 ,at places 
?ree or m glaci]s pluck$ _! way back    
t[>d a common po9t leav+ at _! heads a  
conspicu\s1  %>p-po9t$ peak kn[n z a    
horn4 ,innum]able su* horn peaks occur  
?r\gh\t bo? ! ,lewis & ,liv+/one        
,ranges4 ,excell5t examples  ne> ,logan 
,pass are ,reynolds1 ,be>hat1 & ,clem5ts
 ,m\nta9s4 ,o!r  impos+ horns are ,split
 ,m\nta9 at ! head ( ,r$ ,eagle ,valley1
  ,k9n]ly ,peak 9 ! ,k9tla ,valley1 &   
,m\nt ,wilbur 9 ,swiftcurr5t  ,valley4  
,! horn peak1 because ( its precipit\s  
sides1 is especially  attractive to     
m\nta9 climb]s4 ,! comp>atively rec5t   
dates ( fir/  asc5ts on _m ,p>k peaks   

atte/ to ! difficulties !y (f] !        
m\nta9e]4 ,m\nt ,wilbur1 despite        
proximity to ,_m ,glaci] ,hotel &  camp1
 0 unclimb$ until #aibc2 ,m\nt ,/4      
,ni*olas succumb$ 9 #aibf1  & ! fir/    
asc5t ( ,k9n]ly ,peak 0 made by sev]al  
memb]s ( !  ,si]ra ,club 9 #aicg4       
,ano!r feature ( ! ,p>k :i* mu/ be      
attribut$ p>tly to  glaciation is !     
wat]fall4 ,!re are two pr9cipal types1  
"o :i*  occurs 9 ! bottom ( ! ma9       
valleys & "o at ! m\? ( !  hang+        
tribut>y valleys4 ,! =m]1 exemplifi$ by 
,swiftcurr5t1 ,r$  ,rock1 ,dawn ,mi/1   
,trick1 ,morn+ ,eagle & o!rs1 is locat$ 
:]e  /reams drop ov] ! ris]s ( ! glacial
 /airway4 ,9 o!r words1  resi/ant lay]s 
( rock :i* ! =m] glaci]s 7 unable to    
entirely we> away give rise to ?is type 
( fall4    ,examples ( ! hang+ tribut>y 
type ( fall :i* is due directly to  !   
activity ( ! glaci]s are ,flor5ce1 ,bird
 ,woman1 ,virg9ia1  ,gr9nell1 ,l9coln1 &
 _m o!rs4        ,illu/ration3 ,,trick  
,,falls ,,9 ,,! ,,two ,,m$ic9e ,,riv]   

,no less conspicu\s ?an ! m\nta9s       
!mselves are ! lakes4 ,9 mo/  in/ances  
glaci]s h be5 ei!r directly or          
indirectly responsible  = ! orig9 ( !   
sev]al hundr$ 9 ! ,p>k4 ,9 g5]al1 ^!    
lakes may be divid$ into five ma9 types1
 dep5d+ ^u _! orig94    7#a7 ,cirque    
lakes4 ,?is type ( lake frequ5tly is    
circul> 9 outl9e  & fills ! depression  
pluck$ out ( solid rock by a glaci] at  
its  s\rce4 ,"s ( ! mo/ typical examples
 are li/$ 9 ! =ego+  discussion (       
cirques4    7#b7 ,o!r rock-bas9 lakes4  
,?is type1 ref]r$ to above1 fills bas9s 
creat$ :]e glaci]s mov$ ov] areas (     
comp>atively weak rock4 ,9  all cases ! 
lake is held 9 by a b$rock dam4 ,a      
typical example is  ,swiftcurr5t1 :i*   
lies beh9d a dam ( massive ,altyn       
,lime/one lay]s4  ,! highway1 j be=e x  
rea*es ,_m ,glaci] ,hotel1 crosses ?is  
ris] ( ! glaci] /airway4    7#c7 ,lakes 
held 9 by outwa%4 ,mo/ ( ! l>ge lakes on
 ! we/ side  ( ! ,p>k fall 9 ?is        
category4 ,! dams hold+ 9 ^! lakes are  

compos$ ( /ratifi$ gravel :i* 0 wa%$ out
 f =m] glaci]s  :5 !y ext5d$ d[n into ! 
l[] p>ts ( ! valleys4 ,lake  ,mc,donald1
 l>ge/ 9 ! ,p>k1 is ( ?is type4         
,illu/ration3 ,,/4 ,,m>y ,,lake ,,f     
,,goose ,,isl& ,,ov]look    7#d7 ,lakes 
held by alluvial fans4 ,/4 ,m>y1        
,wat]ton1 ,l[] ,/4 ,m>y1 &  ,l[] ,two   
,m$ic9e ,lakes belong 9 ?is gr\p4 ,^!   
bodies ( wat] may  h be5 rock-bas9      
lakes1 b at a rec5t date on _! hi/ory   
/reams ent]+ ! lake valley h completely 
block$ ! valley )  deposits ( gravel2   
?us ei!r creat+ a lake or rais+ ! level 
(  "o already pres5t4 ,/4 ,m>y & ,l[]   
,/4 ,m>y ,lakes probably 7  jo9$        
orig9ally to make a lake #ag miles long4
 ,m rec5tly ,divide  ,creek1 ent]+ ?is  
long lake f ! s\?1 built an alluvial fan
 (  gravel :]e x ent]$ ! lake4 ,?is fan 
0 l>ge en\gh to cut !  lake into ! two  
pres5t bodies ( wat]4 ,! ,/4 ,m>y       
,entrance ,/ation  at ! ea/]n end (     
,go+-to-!-,sun ,road1 is locat$ on ?is  
alluvial  fan1 ! =m ( :i* c readily be  

di/+ui%$ f a po9t along  ! road at !    
nor? side ( ! upp] lake ne> its outlet4 
7#e7 ,mora9e lakes4 ,mo/ lakes ) mora9es
 at _! outlets are p>tly  damm$ by      
outwa% or rock ridges4 ,"o ( ! prom95t  
examples is  ,joseph9e ,lake ne> ,_m    
,glaci] ,hotel4 ,! mora9e :i* is p>tly  
responsible = ! lake is a hill :i* c be 
se5 f ,_m ,glaci]  ,hotel4 ,sev]al ( !  
l>ge lakes on ! we/ side ( ! ,p>k are   
also  held p>tly or entirely by mora9es4
    ,ano!r type ( mora9e lake1 :i*      
occurs only at ,sp]ry & ,gr9nell        
,glaci]s1 has already be5 m5tion$4 ,x   
diff]s f all o!r ,p>k  lakes 9 hav+ a   
glaci] = "p ( its %orel9e4 ,!re are two 
(  ^! lakes at ,sp]ry & "o at ,gr9nell4 
,despite _! small size1  !y are         
trem5d\sly int]e/+1 n only because ( _! 
relation to  ! glaci]1 b also because !y
 are ord9>ily fill$ ) iceb]gs  ?r\gh\t !
 summ]4 ,_! surfaces (t5 rema9 froz5    
until  mid-summ]4    ,!re are sev]al    
types ( m9or importance1 ! pr9cipal "o (
 :i*  is t =m$ by a l&slide damm+ !     

valley4    ,"o _c rema9 long 9 ,glaci]  
,national ,p>k )\t notic+ !  v>y+ colors
 ( its lake wat]s4 ,9 fact ?is feature  
is s /rik+  t rang]-naturali/s probably 
are que/ion$ m ab\t x ?an ab\t  any o!r 
feature or ph5om5on4 ,to f9d ! answ] we 
mu/ g aga91 z  9 s _m in/ances1 to !    
glaci]s4 ,z ! ice moves x cont9ually    
breaks rock fragm5ts loose4 ,"s ( ^! are
 gr\nd into p[d] z  !y move aga9/ ea*   
o!r & aga9/ ! b$rock "u ! glaci]4  ,mo/ 
types ( rock1 especially ! lime/ones &  
%ales on :i* !  ,p>k glaci]s re/1 :5    
gr\nd f9e en\gh yield a gray p[d]4 ,all 
melt-wat] /reams issu+ f glaci]s are    
cl\dy or milky f _!  load ( ?is f9ely   
gr\nd 8rock fl\r40    ,wat] f ,gr9nell  
,glaci] is s lad5 ) rock fl\r t ! small 
lake along ! edge ( ! ice into :i* !    
wat] p\rs is ne>ly  :ite4 ,mu* ( ! silt 
is deposit$ 9 ?is lake1 b en\gh is c>ri$
  d[n/ream to give ,gr9nell ,lake a     
beautiful turquoise hue4 ,"s ( !  v f9e/
 s$im5t :i* fails to settle 9 ,gr9nell  
,lake is c>ri$ a  mile f>!r to ,joseph9e

 ,lake to give x a blue-gre5 color4 ,ev5
  ,swiftcurr5t ,lake1 /ill f>!r         
d[n/ream1 does n conta9 cle>  wat]4     
,! rock fl\r :i* colors ^! z well z o!r 
,p>k lakes c also  be se5 9 ! /reams4   
,b>+ ,creek at ,sunrift ,gorge 7see p4  
#ac 9  ,motori/'s ,guide7 is milky )    
p[d]$ rock f ,sexton ,glaci]4  ,cat>act 
,creek along ! trail betwe5 ,joseph9e & 
,gr9nell ,lakes is  noticeably milky1   
extraord9>ily s 9 mid-aft]noon on v w>m 
days4  ,at su* times melt+ ( ! glaci]s  
is accel]at$ & m silt is  !n suppli$ to 
! /reams4    ,"p ( ,sp]ry ,glaci]1 9    
contra/ to ,gr9nell1 re/s on a bright r$
  %aly rock 7kn[n to ! geologi/s z      
argillite7 :i* yields a  r$-gray p[d] :5
 f9ely gr\nd4 ,h5ce ! wat] 9 sev]al     
small  lakes adjac5t to ! glaci] has a  
p9ki% t9t4    ,al?\gh a l>ge numb] (    
,p>k /reams are f$ by glaci]s !re are   
_m o!rs1 p>ticul>ly 9 ! s\? & we/       
sections1 :i* h no  ice z _! s\rce4 ,on 
a trail trip f ,sunrift ,gorge to       
,virg9ia  ,falls1 "o is c]ta9 to be     

impress$ by ! extreme cl>ity ( !  wat] 9
 ,virg9ia ,creek4 ,= half a mile bel[ ! 
falls ! trail  foll[s ?is cascad+ torr5t
 f "o cry/al pool to ano!r4 ,s  cle> is 
! wat] t we are apt to mi/ake = wad+    
pools places  :]e ! wat] may be five or 
m feet deep4 ,snyd] ,creek ne> ,lake    
,mc,donald ,lodge ne>ly rivals ,virg9ia 
,creek 9 cl>ity4 ,! s\rces (  ^! two    
/reams obvi\sly are n melt+ glaci]s4    
,f ! =ego+ discussion1 x is evid5t t    
glaci]s con/itute  "o ( ! pr9cipal      
controll+ factors 9 ! color ( ! wat] 9  
,p>k /reams & lakes4 ,:]e !re are no ice
 masses /reams are cle>1  & :]e glaci]s 
occur ! wat] possesses _m %ades v>y+ f  
cle> blue ?r\gh turquoise to gray1 & 9  
r>e cases ev5 p9k4        ,illu/ration3 
,,mora9e ,,ne> ,,gr9nell ,,glaci] ,,is  
#abj ,,feet ,,high4 ,,!      ,,glaci]   
,,ext5d$ ,,ne>ly ,,to ,,top ,,( ,,mora9e
 #ej ,,ye>s ,,ago4 7,,dyson             
,,photo7    ,al?\gh ! =m] l>ge glaci]s (
 ! ,ice ,age transport$ huge  am\nts (  
rock debris d[n ! valleys ( ! ,p>k1 !   

mora9es :i*  !y deposit$ are1 z a rule1 
n conspicu\s features ( !  l&scape4 ,!  
,go+-to-!-,sun ,road1 h[ev]1 crosses    
sev]al  accumulations ( mora9e 9 :i*    
road cuts h be5 made4 ,! road  trav]ses 
a numb] ( su* places along ! %ore (     
,lake ,mc,donald4  ,because ( ! l>ge    
proportions ( rock fl\r 7clay7 9 ^!     
accumulations1 ! mat]ial cont9ually     
slumps1 sometimes slid+ onto  ! road    
surface4 ,"o ( ^! cuts has be5 p>tly    
/abiliz$ by a  lattice-l framework (    
logs4 ,! l>ge/ excavation 9 mora9e along
  ! highway is locat$ ab\t ?ree miles   
ea/ ( ,logan ,pass j bel[  ! big loop   
:]e ! road crosses ,siyeh ,creek4 ,!    
surfaces ( _m  b\ld]s 9 ?is mora9e are  
m>k$ by grooves & scrat*es1 imp>t$  to  
!m z !y 7 scrap$ along ! side ( ! valley
 by ! glaci]  #aj1jjj or m ye>s ago4    
,a small mora9e is expos$ along ! exit  
road f ! p>k+ lot at  ,_m ,glaci]       
,hotel4 ,x conta9s a numb] ( small r$   
b\ld]s1 !  s\rces ( :i* are ! r$ rock   
l$ges 9 ! m\nta9s sev]al miles  up !    

,swiftcurr5t ,valley1 pla9ly visible f !
 hotel4    ,"o ( ^! anci5t mora9es :i*  
has be5 erod$ into a s]ies (  m\nds 7#be
 to #ajj feet high7 ext5ds f            
,swiftcurr5t ,cab9 ,camp d[n  ! valley  
on ! nor? side ( ! road to a po9t ne> ! 
entrance to  ,_m ,glaci] ,rang] ,/ation4
 ,"s ( ! cab9s are actually situat$ 9  a
 space betwe5 two ( ! highe/ m\nds4     
,illu/ration3 ,,look+ ,,s\? ,,along ,,! 
,,gr9nell ,,glaci] ,,ice ,,front4       
,,note ,,crevasses ,,along ,,:i* ,,b]gs 
,,are ,,break+ ,,(f4 7,,dyson ,,photo7  
,surr\nd+ all exi/+ ,p>k glaci]s are two
 sets ( rec5t mora9es  v>y+ 9 height f a
 few feet to m ?an two hundr$4 ,s       
rec5tly  7probably #hjj to #ijj ye>s7 h 
! glaci]s )drawn f ! old]  ( ^! t only  
sp>se will[s & o!r =ms ( dw>f vegetation
  are gr[+ on !m4    ,! y\ng] set (     
mora9es1 :i* has accumulat$ dur+ ! la/  
sev]al hundr$ ye>s1 consi/s ( unwea!r$  
rock on :i* only small  pione] plants & 
li*5s h begun to e/abli% !mselves4 ,^!  
mora9es are p>ticul>ly /rik+ at         

,gr9nell1 ,sp]ry1 ,blackfoot1  ,agassiz 
& ,sexton ,glaci]s4 ,on ! la/ few y>ds (
 ! spectacul>  ,gr9nell ,glaci] trail   
all p]sons :o make ! trip to ! glaci]   
mu/  climb ov] ! mora9e be=e sett+ foot 
on ! ice4 ,f ?is vantage  po9t on !     
highe/ "p ( ?is mora9e ! visitor c look 
d[n ^u  a huge crevass$ mass ( ice ly+ 9
 a /up5d\s rock-wall$  amphi!at]1 !n    
m]ely by fac+ ! opposite direction1 he w
 see  unfold$ be=e 8 view "o ( ! mo/    
colorful vi/as 9 ! ,p>k4  ,m ?an a ?\s& 
feet bel[ 9 ! head ( a spl5did ,u-%ap$  
valley lies ! turquoise gem ( ,gr9nell  
,lake4 ,a mile f>!r away !  blue surface
 ( ,lake ,joseph9e /&s out 9 %>p contra/
 to ! d>k  gre5 ( ! spruce :i* l9es its 
%ores4 ,high above he c see !  r$ summit
 ( ,m\nt ,all5 c>ry+ its :ite sn[banks  
into ! deep  blue ( a ,montana sky4     
,despite ?is magnific5ce ! visitor mu/  
soon  turn 8 att5tion to ! trem5d\s     
accumulation ^u :i* he /&s1  = x is no  
less int]e/+ ?an ! m\nta9s & lakes4     
,among !  _m b\ld]s :i* lie along ! pa? 

are two prom95t lime/one  blocks ea* #aj
 to #ae feet 9 diamet]4 ,! und]side ( "o
 0 groov$  & poli%$ z ! ice pu%$ x      
across ! rock surface und]ly+ !  glaci]4
 ,! o!r1 p>tially emb$d$ 9 ! mora9e1 has
 a poli%$  upp] surface because ! glaci]
 fl[$ ov] x = a "t4 ,bo? ^!  b\ld]s1    
al?\gh n[ ne>ly #cjj y>ds f ! ice front1
 7 cov]$  by ! glaci] until ab\t #bj    
ye>s ago4    ,because ( %r9kage _m ( !  
glaci]s are no long] 9 contact )  ^!    
new] mora9es4 ,9 "s cases a qu>t] ( a   
mile ( b>e rock  surface int]v5es betwe5
 ! mora9e & ! glaci] :i* made x4    ,a  
few glaci]s h disappe>$ )9 rec5t ye>s1 b
 _! mora9es  rema9 z evid5ce ( =m]      
glaci] activity4 ,"o ( ! mo/ notable    
examples is af=d$ by ,clem5ts ,glaci]1 a
 small body ( ice :i*  exi/$ until ab\t 
#aich 9 ! %ad[ ( ,clem5ts ,m\nta9 at    
,logan  ,pass4 ,its edge 0 bord]$ by a  
ridge-l mora9e ne>ly a hundr$  feet     
high4 ,today1 ! trail f ,logan ,pass to 
,hidd5 ,lake skirts !  outside edge ( ! 
mora9e4 ,%\ld ! hik] leave ! trail &    

climb  ! few y>ds to ! top ( ?is mora9e 
he c\ld see x /ret*$ out  be=e him z a  
giant necklace encircl+ ! base (        
,clem5ts ,m\nta91  b betwe5 m\nta9 &    
mora9e1 :]e a few ye>s ago ! glaci] lay1
  he w see only b>e rock or drift$ sn[4 
,despite rec5t rapid %r9kage ( glaci]s &
 ! disappe>ance (  "s1 ,glaci] ,national
 ,p>k /ill is a l& ( ice1 yet :5 !      
visitor  views its pres5t day glaci]s & 
its sublimely beautiful m\nta9  sc5]y he
 %\ld n be unm9dful ( ! p[]ful =ces :i*1
 work+  dur+ _m ?\s&s ( ye>s1 h br\ght x
 all ab\t4 ,!n1 &  only !n1 c he prop]ly
 appreciate ! magnific5ce :i* ,nature   
has  s g5]\sly be/[$ ^u u4              
,illu/ration3 ,,clem5ts ,,m\nta9 ,,&    
,,glaci]4 ,,! ,,glaci] ,,has ,,s9ce     
,,disappe>$4 7,,hileman ,,photo7        
,,footnotes      #a;,dr4 ,dyson work$ z 
a rang] naturali/ 9 ,glaci] ,national   
,p>k =      eight diff]5t summ]s />t+ 9 
#aice4 ,dur+ t "t he      und]took      
special rese>* on p>k glaci]s 9 addition
 to 8      regul> assignm5ts4    #b;,= a

 brief description ( ^! rock =mations   
see ,special ,bullet9      ,no4 #c      
7,geologic ,/ory7 ( ! ,glaci] ,natural  
,hi/ory ,association4                   
,,glaci] ,,natural ,,hi/ory             
,,association1 ,inc4                    
,glaci] ,national ,p>k                  
,we/ ,glaci]1 ,montana      ,organiz$ = 
! purpose ( coop]at+ ) ! ,national ,p>k 
,s]vice  by assi/+ ! ,int]pretive       
,division ( ,glaci] ,national ,p>k 9 !  
developm5t ( a broad public und]/&+ ( ! 
geology1 plant &  animal life1 hi/ory1  
,indians1 & relat$ subjects be>+ on !   
p>k  region4 ,x aids 9 ! developm5t ( ! 
,glaci] ,national ,p>k libr>y1  museums1
 & wayside exhibits2 (f]s books on      
natural hi/ory = sale  to ! public2     
assi/s 9 ! acquisition ( non-f$]ally    
own$ l&s  )9 ! p>k 9 behalf ( ! ,unit$  
,/ates ,gov]nm5t2 &  coop]ates ) !      
,gov]nm5t 9 ! int]e/ ( ,glaci] ,national
 ,p>k4    ,rev5ues obta9$ by !          
,association are devot$ entirely to !   
purposes outl9$4 ,any p]son int]e/$ 9 ! 

fur!rance ( ^!  purposes may become a   
memb] ^u paym5t ( ! annual fee ( "o     
doll>4 ,gifts & donations are accept$ = 
l& acquisition or g5]al  use4           
,illu/ration3 ,,glaci] ,,natural        
,,hi/ory ,,association ,,inc4           
,transcrib]'s ,notes      --,sil5tly    
correct$ a few typos4    --,reta9$      
publication in=mation f ! pr9t$ edition3
 ?is e,book    is public-doma9 9 !      
c\ntry ( publication4    --,9 ! text    
v]sions only1 text 9 italics is delimit$
 by    und]scores4