﻿330 
  EEV. 
  E. 
  BARON 
  ON 
  THE 
  GEOLOGY 
  OE 
  MADAGASCAR. 
  

  

  near 
  the 
  coast 
  as 
  implying 
  non-elevation, 
  we 
  may 
  conclude 
  that 
  

   the 
  island 
  generally 
  is 
  at 
  present 
  stationary. 
  It 
  appears, 
  how- 
  

   ever, 
  that 
  the 
  southern 
  part 
  of 
  the 
  country 
  has 
  undergone 
  recent 
  

   elevation. 
  This 
  is 
  shown 
  by 
  the 
  existence 
  of 
  extensive 
  coral-beds, 
  

   to 
  the 
  accumulation 
  of 
  which, 
  M. 
  Grandidier 
  says, 
  the 
  southern 
  part 
  

   of 
  the 
  island 
  seems 
  to 
  be 
  due. 
  Capt. 
  Larsen 
  says 
  that 
  raised 
  beaches 
  

   may 
  be 
  seen 
  in 
  certain 
  parts 
  of 
  the 
  south-west 
  of 
  the 
  island, 
  and 
  

   Mr. 
  Sibree 
  informs 
  me 
  that 
  he 
  met 
  with 
  them 
  to 
  the 
  south-east. 
  

  

  Another 
  question 
  of 
  interest 
  is, 
  at 
  what 
  period, 
  if 
  ever, 
  was 
  there 
  

   a 
  land 
  connexion 
  between 
  Madagascar 
  and 
  Africa 
  ? 
  That 
  the 
  

   island 
  once 
  formed 
  part 
  of 
  the 
  mainland 
  cannot 
  well 
  be 
  doubted 
  

   when 
  we 
  remember 
  the 
  relationship 
  existing 
  between 
  the 
  faunas, 
  

   and 
  the 
  close 
  affinity 
  between 
  the 
  floras, 
  of 
  Madagascar 
  and 
  the 
  

   adjacent 
  continent. 
  If 
  we 
  accept 
  Mr. 
  "Wallace's 
  theory 
  as 
  correct, 
  

   that 
  the 
  character 
  of 
  the 
  Madagascar 
  fauna 
  points 
  to 
  the 
  separa- 
  

   tion 
  of 
  the 
  island 
  from 
  the 
  mainland 
  previous 
  to 
  the 
  migration 
  into 
  

   Africa 
  from 
  the 
  Euro-Asiatic 
  continent 
  of 
  the 
  higher 
  forms 
  of 
  mam- 
  

   mals, 
  then 
  it 
  follows 
  that 
  Madagascar 
  became 
  an 
  island 
  at 
  least 
  not 
  

   subsequent 
  to 
  the 
  later 
  Pliocene 
  period 
  (for 
  the 
  migration 
  probably 
  

   took 
  place 
  in 
  early 
  Pliocene 
  times, 
  if 
  not 
  even 
  in 
  later 
  Miocene), 
  

   since 
  which 
  it 
  must 
  have 
  remained 
  isolated 
  from 
  the 
  mainland 
  until 
  

   the 
  present 
  day, 
  as 
  the 
  absence 
  of 
  such 
  mammals 
  proves 
  *. 
  More- 
  

   over, 
  during 
  a 
  portion, 
  at 
  any 
  rate, 
  of 
  Eocene 
  (as 
  also 
  of 
  Jurassic 
  

   and 
  Cretaceous) 
  time, 
  the 
  western 
  part 
  of 
  the 
  island 
  was 
  beneath 
  

   the 
  sea, 
  a 
  fact 
  shown 
  by 
  the 
  presence 
  of 
  almost 
  continuous 
  nummu- 
  

   litic 
  limestone 
  on 
  the 
  west 
  coast. 
  Erom 
  these 
  considerations 
  we 
  

   may 
  conclude 
  that 
  Madagascar 
  was 
  probably 
  connected 
  with 
  Africa 
  

   during 
  some 
  portion 
  or 
  portions 
  or 
  the 
  whole 
  of 
  the 
  time 
  between 
  

   the 
  Eocene 
  and 
  at 
  least 
  the 
  later 
  Pliocene 
  period 
  f 
  (allowing 
  time 
  

   for 
  the 
  migration 
  of 
  the 
  mammals 
  to 
  Southern 
  Africa, 
  which 
  would 
  

   not 
  unlikely 
  keep 
  pace 
  with 
  the 
  gradual 
  refrigeration 
  of 
  the 
  northern 
  

   hemisphere), 
  after 
  which 
  the 
  sea 
  again 
  divided 
  it 
  from 
  the 
  adjacent 
  

   continent, 
  and 
  has 
  kept 
  it 
  isolated 
  to 
  the 
  present 
  day. 
  

  

  In 
  conclusion 
  I 
  have 
  only 
  to 
  express 
  my 
  regret 
  at 
  the 
  imperfect 
  

   character 
  of 
  the 
  present 
  paper. 
  It 
  only 
  professes 
  to 
  deal 
  in 
  a 
  general 
  

   way, 
  as 
  its 
  title 
  indicates, 
  with 
  a 
  few 
  of 
  the 
  more 
  prominent 
  features 
  

   of 
  the 
  geology 
  of 
  Madagascar. 
  Some 
  of 
  the 
  statements 
  made, 
  it 
  is 
  

   not 
  unlikely, 
  when 
  the 
  region 
  has 
  been 
  more 
  thoroughly 
  examined, 
  

  

  * 
  That 
  Madagascar 
  has 
  for 
  a 
  very 
  long 
  period 
  been 
  separated 
  from 
  the 
  main- 
  

   land 
  is 
  also 
  proved 
  by 
  the 
  character 
  of 
  its 
  flora 
  ; 
  for 
  while 
  about 
  five-sixths 
  of 
  

   its 
  genera 
  of 
  plants 
  are 
  found 
  in 
  other 
  (chiefly 
  tropical) 
  countries, 
  four-fifths 
  

   (if 
  not 
  a 
  larger 
  proportion) 
  of 
  its 
  species 
  are 
  peculiar 
  to 
  the 
  island. 
  This 
  shows 
  

   that 
  a 
  very 
  lengthened 
  period 
  of 
  isolation 
  must 
  have 
  elapsed 
  to 
  have 
  allowed 
  of 
  

   such 
  a 
  large 
  amount 
  of 
  specific 
  differentiation. 
  

  

  t 
  This 
  would 
  seem 
  to 
  be 
  confirmed 
  by 
  what 
  we 
  know 
  respecting 
  the 
  Lemurs, 
  

   the 
  Centetidas, 
  and 
  the 
  Civets, 
  which 
  groups 
  compose 
  about 
  five-sixths 
  of 
  the 
  

   Madagascar 
  Mammalia, 
  and 
  the 
  ancestors 
  of 
  all 
  of 
  which 
  existed 
  in 
  Europe 
  

   in 
  early 
  Tertiary 
  times. 
  It 
  must 
  have 
  been 
  posterior 
  to 
  the 
  Eocene 
  but 
  ante- 
  

   rior 
  at 
  least 
  to 
  the 
  Pliocene 
  (or 
  later 
  Miocene) 
  period 
  (when 
  the 
  large 
  animals 
  

   were 
  driven 
  southward) 
  that 
  these 
  lowly 
  organized 
  creatures 
  spread 
  as 
  far 
  as 
  

   Madagascar, 
  the 
  existence 
  of 
  which 
  in 
  the 
  island 
  is 
  unaccountable 
  except 
  on 
  the 
  

   theory 
  of 
  a 
  former 
  connexion 
  with 
  the 
  mainland. 
  

  

  