﻿372 
  A. 
  Agassis 
  — 
  Explorations 
  of 
  the 
  " 
  Albatross." 
  

  

  tions 
  of 
  the 
  individual 
  islands, 
  but 
  also 
  according 
  to 
  the 
  geo- 
  

   graphical 
  position 
  of 
  the 
  groups. 
  Thus 
  far 
  I 
  do 
  not 
  think 
  any 
  

   observer 
  has 
  given 
  sufficient 
  weight 
  to 
  the 
  importance 
  of 
  the 
  

   action 
  of 
  the 
  trades 
  in 
  modifying 
  the 
  islands 
  within 
  the 
  limits 
  

   of 
  the 
  trades, 
  nor 
  has 
  anyone 
  noticed 
  that 
  the 
  coral 
  reefs 
  are 
  all 
  

   situated 
  practically 
  within 
  the 
  limits 
  of 
  the 
  trades 
  both 
  north 
  

   and 
  south 
  of 
  the 
  equator. 
  

  

  The 
  soundings 
  made 
  going 
  west 
  from 
  Jaluit 
  to 
  Namonuito 
  

   indicate 
  that 
  there 
  is 
  no 
  great 
  plateau 
  from 
  which 
  the 
  Caro- 
  

   lines 
  rise, 
  but 
  that 
  the 
  various 
  groups 
  are, 
  as 
  is 
  the 
  case 
  with 
  

   the 
  neighboring 
  groups 
  of 
  the 
  Marshalls 
  and 
  Gilberts, 
  isolated 
  

   peaks 
  with 
  steep 
  slopes 
  rising 
  from 
  a 
  depth 
  of 
  over 
  2000 
  

   fathoms. 
  The 
  line 
  we 
  ran 
  from 
  the 
  northern 
  end 
  of 
  Namon- 
  

   uito 
  to 
  Guam 
  developed 
  the 
  eastern 
  extension 
  of 
  a 
  deep 
  trough 
  

   running 
  south 
  of 
  the 
  Ladrones. 
  The 
  existence 
  of 
  this 
  trough 
  

   had 
  been 
  indicated 
  by 
  a 
  sounding 
  of 
  4475 
  fathoms 
  to 
  the 
  south- 
  

   west 
  of 
  Guam 
  made 
  by 
  the 
  Challenger. 
  We 
  obtained, 
  about 
  

   100 
  miles 
  southeast 
  of 
  Guam, 
  a 
  depth 
  of 
  4813 
  fathoms, 
  a 
  

   depth 
  surpassed 
  only, 
  if 
  I 
  am 
  not 
  in 
  error, 
  by 
  three 
  soundings 
  

   made 
  by 
  the 
  Penguin 
  in 
  the 
  deep 
  trough 
  extending 
  from 
  

   Tonga 
  to 
  the 
  Kermadecs. 
  

  

  I 
  was 
  very 
  much 
  surprised, 
  in 
  approaching 
  Guam 
  from 
  the 
  

   eastward, 
  to 
  find 
  that 
  the 
  island 
  was 
  not 
  wholly 
  volcanic, 
  but 
  

   that 
  the 
  northern 
  half 
  consists 
  of 
  elevated 
  coralliferous 
  lime- 
  

   stone. 
  The 
  vertical 
  cliffs 
  bordering 
  the 
  eastern 
  face 
  rise 
  from 
  

   a 
  height 
  of 
  100 
  to 
  250 
  or 
  300 
  feet 
  at 
  the 
  northern 
  extremity, 
  

   and 
  resemble 
  in 
  a 
  way 
  similar 
  islands 
  in 
  the 
  Paumotus 
  

   (Makatea), 
  Niue, 
  Eua, 
  Yavau 
  and 
  others 
  in 
  the 
  Fijis 
  which 
  

   had 
  made 
  their 
  cliffs 
  a 
  familiar 
  feature 
  in 
  our 
  explorations. 
  

   In 
  fact, 
  outside 
  of 
  Yiti 
  Levu 
  and 
  Yanua 
  Levu, 
  this 
  is 
  the 
  

   largest 
  island 
  known 
  to 
  me 
  where 
  we 
  find 
  a 
  combination 
  of 
  

   volcanic 
  rocks 
  and 
  of 
  elevated 
  coralliferous 
  limestone. 
  The 
  

   massif 
  forming 
  the 
  southern 
  half 
  of 
  the 
  island 
  is 
  volcanic, 
  and 
  

   the 
  highest 
  ridge, 
  rising 
  to 
  about 
  1000 
  feet, 
  runs 
  parallel 
  to 
  the 
  

   west 
  coast, 
  the 
  longest 
  slope 
  being 
  toward 
  the 
  east. 
  

  

  This 
  volcanic 
  mass 
  has 
  burst 
  through 
  the 
  limestone 
  near 
  

   Agana, 
  and 
  the 
  outer 
  western 
  extension 
  of 
  the 
  coralliferous 
  

   limestone 
  exists 
  only 
  in 
  the 
  shape 
  of 
  a 
  few 
  spurs 
  running 
  out 
  

   from 
  the 
  volcanic 
  mass, 
  the 
  largest 
  of 
  which 
  are 
  those 
  forming 
  

   the 
  port 
  of 
  San 
  Luis 
  d'Apra. 
  These 
  spurs 
  are 
  separated 
  by 
  

   lower 
  ridges 
  of 
  volcanic 
  rocks 
  extending 
  to 
  the 
  sea 
  from 
  the 
  

   main 
  central 
  mass. 
  To 
  the 
  north 
  of 
  Agana 
  the 
  limestone 
  

   forms 
  an 
  immense 
  irregular 
  mesa, 
  cut 
  by 
  deep 
  crevasses, 
  full 
  

   of 
  pot-holes 
  and 
  sinks, 
  rising 
  gradually 
  westward 
  to 
  a 
  height 
  of 
  

   350 
  or 
  400 
  feet. 
  Near 
  the 
  northern 
  extremity 
  of 
  the 
  island 
  a 
  

   volcanic 
  mass, 
  Mt. 
  Santa 
  Rosa, 
  has 
  burst 
  through 
  the 
  limestone 
  

   and 
  rises 
  about 
  150 
  feet 
  above 
  the 
  general 
  level 
  of 
  that 
  part 
  of 
  

  

  