﻿Verrill 
  — 
  Notes 
  on 
  the 
  Geology 
  of 
  the 
  Bermudas. 
  323 
  

  

  15. 
  Probably 
  the 
  greatest 
  elevation 
  of 
  the 
  Greater 
  Bermuda 
  

   was 
  coincident 
  in 
  time 
  with 
  the 
  Glacial 
  Period 
  of 
  North 
  

   America 
  and 
  Europe. 
  The 
  same 
  elevation 
  of 
  the 
  northern 
  

   regions 
  of 
  America 
  and 
  Europe 
  which 
  produced 
  the 
  Glacial 
  

   Period, 
  or 
  was 
  coincident 
  therewith, 
  also 
  affected 
  Bermuda, 
  

   which 
  lies 
  only 
  about 
  TOO 
  miles 
  south 
  of 
  Nova 
  Scotia, 
  where 
  

   the 
  elevation 
  was 
  far 
  greater 
  in 
  extent. 
  (See 
  p. 
  337.) 
  

  

  16. 
  The 
  period 
  of 
  greatest 
  subsidence 
  was 
  probably 
  coinci- 
  

   dent 
  in 
  time 
  with 
  the 
  Post-Glacial 
  or 
  Laurentian 
  period 
  of 
  sub- 
  

   mergence 
  on 
  our 
  coast. 
  The 
  subsequent 
  small 
  elevation, 
  after 
  

   the 
  greatest 
  subsidence, 
  is 
  supposed 
  to 
  have 
  been 
  only 
  six 
  to 
  

   ten 
  feet, 
  while 
  the 
  coasts 
  of 
  Nova 
  Scotia 
  and 
  northern 
  New 
  

   England 
  have 
  been 
  elevated 
  more 
  than 
  100 
  feet 
  since 
  the 
  

   greatest 
  depression. 
  This 
  movement, 
  also, 
  was 
  probably 
  due 
  to 
  

   the 
  same 
  causes 
  in 
  both 
  places. 
  

  

  17. 
  The 
  climate 
  of 
  the 
  Greater 
  Bermuda 
  was 
  warmer, 
  more 
  

   windy, 
  and 
  more 
  moist 
  than 
  at 
  present, 
  so 
  that 
  certain 
  West 
  

   Indian 
  species 
  have 
  become 
  extinct 
  in 
  Bermuda, 
  but 
  are 
  found 
  

   as 
  fossils 
  in 
  the 
  old 
  limestone, 
  mingled 
  with 
  other 
  species 
  still 
  

   common 
  on 
  the 
  islands. 
  The 
  storms 
  were 
  probably 
  more 
  

   severe, 
  owing 
  to 
  the 
  proximity 
  of 
  the 
  glaciated 
  American 
  

   coast, 
  and 
  consequent 
  sharper 
  contrasts 
  in 
  temperature. 
  (See 
  

   p. 
  338.) 
  

  

  IS. 
  The 
  visible 
  Bermudas, 
  and 
  also 
  the 
  Greater 
  Bermuda, 
  

   rest 
  on 
  the 
  hidden 
  summit 
  of 
  an 
  ancient 
  volcano. 
  This 
  ancient 
  

   volcano 
  is 
  conical 
  in 
  form 
  and 
  rises 
  over 
  15,000 
  feet 
  above 
  the 
  

   bottom 
  of 
  the 
  surrounding 
  deep-sea. 
  The 
  slope 
  of 
  this 
  sub- 
  

   merged 
  volcano 
  is 
  exceedingly 
  steep, 
  thus 
  indicating 
  its 
  vol- 
  

   canic 
  nature, 
  which 
  is 
  confirmed 
  by 
  very 
  unusual 
  local 
  magnetic 
  

   variations 
  about 
  the 
  islands.* 
  These 
  variations 
  indicate 
  the 
  

   presence 
  of 
  large 
  masses 
  of 
  iron-bearing 
  volcanic 
  rock 
  at 
  no 
  

   great 
  depth 
  below 
  the 
  surface. 
  

  

  This 
  volcanic 
  cone 
  probably 
  had 
  a 
  considerable 
  elevation 
  

   above 
  the 
  sea, 
  but 
  was 
  cut 
  down 
  to 
  or 
  below 
  sea 
  level 
  by 
  the 
  

   waves 
  to 
  form 
  the 
  foundations 
  of 
  the 
  Greater 
  Bermuda. 
  

  

  19. 
  Two 
  other 
  similar, 
  but 
  smaller, 
  peaks 
  lie 
  a 
  few 
  miles 
  to 
  

   the 
  southwest 
  of 
  Bermuda, 
  and 
  form 
  what 
  are 
  known 
  as 
  Argus 
  

   Bank 
  and 
  Challenger 
  Bank,f 
  both 
  having, 
  in 
  general, 
  from 
  20 
  

   to 
  40 
  fathoms 
  of 
  water 
  over 
  their 
  surfaces, 
  but 
  Argus 
  Bank 
  

  

  Voyage 
  of 
  the 
  Challenger, 
  Narrative, 
  I, 
  p. 
  140: 
  "The 
  observations 
  made 
  

   by 
  the 
  Expedition 
  showed 
  that 
  the 
  variation 
  differed 
  in 
  various 
  parts 
  of 
  the 
  

   island 
  as 
  much 
  as 
  6°, 
  ranging 
  from 
  4° 
  W. 
  to 
  10° 
  W., 
  the 
  smallest 
  amount 
  being- 
  

   found 
  at 
  a 
  small 
  islet 
  just 
  under 
  the 
  lighthouse 
  on 
  GibVs 
  Hill, 
  and 
  the 
  greatest 
  at 
  

   the 
  point 
  on 
  the 
  west 
  side 
  of 
  Clarence 
  Cove." 
  Such 
  variations 
  do 
  not 
  exist 
  at 
  sea, 
  

   a 
  lew 
  miles 
  from 
  the 
  islands. 
  

  

  + 
  The 
  nearest 
  is 
  the 
  Challenger 
  Bank. 
  It 
  lies 
  13 
  miles 
  S. 
  50° 
  14' 
  W. 
  from 
  

   - 
  Hill 
  light 
  It 
  is 
  about 
  10 
  miles 
  in 
  circumference. 
  The 
  distance 
  from 
  the 
  

   100 
  fathom 
  line 
  of 
  Bermuda 
  to 
  its 
  inner 
  edge 
  is 
  not 
  over 
  four 
  miles. 
  

  

  