AS^mber^L'}     Vegetation  of  Yellowstone  Hot  Springs.  629 
mation  about  these  springs,  it  will  be  remembered,  is  calcareous, 
and  to  this  fact  is  due  its  distinctive  character,  so  different  from  the 
silica  formations  which  prevail  elsewhere  in  the  Park.  "  The  over- 
hanging bowls  which  these  deposits  build  up  are  among  the  finest 
specimens  of  Nature's  work  in  the  world,  while  the  water  that  fills 
them  is  of  that  peculiar  beauty  to  be  found  only  in  thermal  springs." 
Cleopatra  Spring,  Jupiter  Terrace,  Pulpit  Terrace,  Minerva  Terrace, 
are  among  the  most  interesting  and  beautiful  of  the  active  springs. 
One  of  the  most  beautiful  is  a  pool  filled  with  pellucid  water  in  vio- 
lent ebullition.  The  sides  and  bottom  of  the  basin  are  formed  of  pure 
white  travertine,  while  the  varying  depths  cause  the  water  to  appear 
all  shades  of  blue  and  green,  from  a  deep  peacock  blue  in  the  deeper 
parts  of  the  bowl,  to  the  lightest  of  Nile  greens  in  the  shallow  re- 
cesses. In  wandering  about  the  terraces,  one  is  much  impressed 
with  the  brightly  tinted  basins  about  the  springs,  and  the  red  and 
orange  colors  of  the  slopes  overflowed  by  the  hot  waters.  These 
colors  are  due  to  the  presence  of  the  microscopic  plants,  algae  of 
several  forms  and  species.  In  the  cooler  springs  and  channels  simi- 
lar vegetation  forms  the  bright  green,  orange  or  brown  mem- 
brane-like sheets,  or  masses  of  jelly  without  apparent  vegetal  struc- 
ture. Silken  yellow  filaments  are  found  in  bowls  and  channels  of 
the  hottest  springs.  Words  fail  to  convey  an  adequate  idea  of  the 
massive  marble-like  terraces,  rising  tier  upon  tier,  and  the  exquisite 
coloring  of  their  sides  and  the  margins  of  the  bowls  filled  with 
steaming  hot  water  of  most  magnificent  iridescent  hues. 
The  silicious  formations  are  similar,  although  not  raised  in  ter- 
races so  grand  or  imposing,  simply  because  the  formation  of  silicious 
sinter  is  much  slower  than  the  formation  of  the  travertine,  and 
because  the  region  seems  to  be  of  later  geologic  age.  Many  of  the 
geyser  cones  are  bee-hive  in  shape,  of  a  white  adamantine- like 
appearance,  and  are,  as  a  rule,  delicately  colored  by  pale  greens  and 
pinks  of  exquisite  variation.  The  many  hundreds  of  springs  of  the 
Upper  Geyser  Basin,  where  they  are  seen  at  their  best,  are  generally 
characterized  by  the  transparent  clearness  of  the  water,  which 
appears  of  varying  shades  of  blue  and  green,  according  to  the  depth 
and  amount  of  light  admitted.  Morning  Glory  Spring  is  one  of  the 
most  beautiful  springs  of  the  Park,  with  a  funnel-shaped  cone  sug- 
gesting the  flower,  and  with  walls  most  delicately  colored. 
Black  Sand  Basin  is,  however,  most   interesting  for  our  pur- 
