﻿552 
  Geological 
  Society 
  : 
  — 
  

  

  immediately 
  below 
  the 
  coal. 
  Apparently 
  overlying 
  the 
  sandstones 
  

   are 
  palagonite-tuffs, 
  shales, 
  and 
  hard 
  limestones 
  of 
  Miocene 
  age. 
  

   The 
  Eocene 
  sandstones 
  are 
  occasionally 
  overlaid 
  by 
  soft 
  sandy 
  strata, 
  

   probably 
  Pliocene, 
  with 
  which 
  naphtha-bearing 
  beds 
  are 
  inter- 
  

   stratified. 
  Naphtha 
  in 
  quantity, 
  under 
  considerable 
  gas 
  -pressure, 
  

   has 
  been 
  obtained 
  from 
  borings, 
  a 
  section 
  of 
  one 
  of 
  which 
  is 
  given, 
  

   300 
  feet 
  deep. 
  The 
  strata 
  are 
  much 
  disturbed 
  and 
  are 
  nearly 
  

   vertical 
  in 
  places. 
  A 
  stony 
  clay 
  having 
  no 
  apparent 
  connexion 
  with 
  

   the 
  present 
  drainage-system, 
  and 
  containing 
  scratched, 
  striated, 
  and 
  

   facetted 
  boulders, 
  spreads 
  unconformably 
  over 
  all 
  the 
  formations 
  

   previously 
  mentioned. 
  At 
  the 
  Hora 
  lighthouse 
  a 
  well-marked 
  

   * 
  raised 
  beach 
  ' 
  occurs 
  at 
  130 
  feet 
  above 
  present 
  sea-level, 
  sometimes 
  

   cemented 
  into 
  a 
  concrete, 
  in 
  which 
  occur 
  Dreissena 
  polymorpha 
  and 
  

   a 
  Neritina, 
  probably 
  N. 
  danubialis. 
  The 
  fresh 
  water 
  within 
  the 
  Sea 
  

   of 
  Marmora 
  must 
  at 
  this 
  epoch 
  have 
  stood 
  at 
  a 
  height 
  sufficient 
  to 
  

   collect 
  the 
  drainage 
  of 
  the 
  whole 
  of 
  South-eastern 
  Europe 
  and 
  

   "Western 
  Asia, 
  an 
  area 
  of 
  at 
  least 
  2,000,000 
  square 
  miles, 
  into 
  a 
  fresh- 
  

   water 
  sea, 
  from 
  which 
  the 
  volume 
  of 
  water 
  discharged 
  (even 
  with 
  

   the 
  present 
  small 
  rainfall) 
  would 
  be 
  not 
  less 
  than 
  twice 
  that 
  of 
  

   Niagara. 
  The 
  Dardanelles 
  channel 
  is 
  itself 
  a 
  gorge 
  cut 
  back 
  through 
  

   soft 
  horizontal 
  Miocene 
  strata, 
  with 
  every 
  appearance 
  of 
  rapid 
  

   erosion 
  by 
  falling 
  water. 
  

  

  2. 
  ' 
  On 
  the 
  Geological 
  and 
  Physical 
  Development 
  of 
  Dominica 
  ; 
  

   with 
  Notes 
  on 
  Martinique, 
  St. 
  Lucia, 
  St. 
  Vincent, 
  and 
  the 
  Grena- 
  

   dines.' 
  By 
  Prof. 
  Joseph 
  William 
  Winthrop 
  Spencer, 
  Ph.D.. 
  M.A., 
  

   F.G.S. 
  

  

  These 
  islands 
  form 
  a 
  continuation 
  of 
  the 
  volcanic 
  chain 
  extending 
  

   from 
  Guadeloupe, 
  though 
  separated 
  one 
  from 
  the 
  other 
  by 
  embayments 
  

   in 
  the 
  submarine 
  plateau, 
  reaching 
  to 
  depths 
  of 
  more 
  than 
  6000 
  

   feet, 
  within 
  the 
  line 
  connecting 
  the 
  shores 
  of 
  the 
  islands. 
  These 
  

   submarine 
  valleys 
  head 
  in 
  cirques, 
  like 
  the 
  amphitheatres 
  which 
  

   occur 
  on 
  the 
  slopes 
  descending 
  from 
  high 
  plateaux. 
  From 
  the 
  ends 
  

   of 
  the 
  cirques, 
  valley-like 
  channels 
  can 
  be 
  traced 
  landward 
  on 
  the 
  

   submerged 
  plateaux, 
  or 
  can 
  be 
  found 
  to 
  cross 
  them 
  in 
  order 
  to 
  join 
  

   like 
  features 
  on 
  the 
  other 
  side. 
  The 
  cols 
  between 
  the 
  opposite 
  valleys 
  

   vary 
  in 
  depth 
  from 
  about 
  2000 
  to 
  3600 
  feet, 
  except 
  that 
  between 
  

   the 
  Grenadines 
  and 
  the 
  Trinidad 
  banks, 
  where 
  the 
  divide 
  may 
  not 
  

   be 
  more 
  than 
  750 
  feet 
  below 
  the 
  surface 
  o£ 
  the 
  sea, 
  and 
  one 
  south 
  

   of 
  St. 
  Vincent 
  (less 
  than 
  1300 
  feet). 
  Some 
  of 
  the 
  submarine 
  

   channels 
  have 
  remarkable 
  tributaries. 
  The 
  drowned 
  valleys, 
  like 
  

   those 
  about 
  the 
  islands 
  to 
  the 
  north, 
  assume 
  two 
  very 
  different 
  

   forms 
  — 
  those 
  with 
  broad 
  undulating 
  outlines, 
  such 
  as 
  characterize 
  

   the 
  features 
  produced 
  during 
  the 
  long 
  Miocene- 
  Pliocene 
  period 
  of 
  

   erosion, 
  when 
  the 
  surfaces 
  of 
  the 
  land 
  were 
  at 
  or 
  near 
  the 
  base-level 
  

   of 
  erosion, 
  and 
  other 
  types 
  where 
  very 
  deep 
  valleys 
  and 
  gorges 
  

   incise 
  the 
  more 
  rounded 
  features 
  of 
  the 
  drowned 
  plateau, 
  which 
  in 
  

  

  