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  PRESIDENTIAL 
  ADDEESS. 
  

  

  (Delivered 
  10th 
  February, 
  1911.) 
  

  

  A 
  SKETCH 
  OF 
  THE 
  CHIEF 
  GEOLOGICAL 
  ZONES 
  AND 
  THEIR 
  

  

  MOLLUSC 
  A. 
  

  

  By 
  R. 
  BuLLEi^ 
  Newton, 
  F.G.S. 
  

  

  The 
  subject 
  of 
  my 
  Address 
  has 
  been 
  chosen 
  with 
  a 
  view 
  of 
  placing 
  

   before 
  the 
  Society 
  one 
  of 
  the 
  many 
  important 
  applications 
  of 
  the 
  fossil 
  

   Mollusca. 
  In 
  the 
  brief 
  history 
  that 
  will 
  be 
  submitted 
  it 
  will 
  be 
  

   observed 
  that 
  molluscan 
  species 
  have 
  been 
  frequently 
  selected 
  as 
  

   index-fossils 
  for 
  the 
  determination 
  of 
  certain 
  subdivisions 
  of 
  the 
  

   sedimentary 
  rocks 
  which 
  are 
  known 
  as 
  geological 
  zones. 
  To 
  the 
  

   ordinary 
  student 
  of 
  modern 
  Mollusca 
  fossil 
  shells 
  present 
  few 
  features 
  

   of 
  interest, 
  probably 
  on 
  account 
  of 
  their 
  frequently 
  imperfect 
  

   condition 
  or 
  because 
  an 
  acquaintance 
  with 
  geological 
  questions 
  is 
  

   indispensable 
  before 
  attempting 
  their 
  study 
  or 
  determination. 
  The 
  

   palseoconchologist, 
  it 
  is 
  only 
  too 
  true, 
  has 
  often 
  to 
  be 
  content 
  with 
  

   fragmentary 
  and 
  mineralized 
  specimens 
  and 
  sometimes 
  casts 
  or 
  even 
  

   impressions, 
  from 
  a 
  study 
  of 
  which 
  lie 
  is 
  expected 
  to 
  solve 
  problems 
  

   relating 
  to 
  the 
  geological 
  age 
  of 
  the 
  shell 
  or 
  assemblage 
  of 
  shells, 
  as 
  

   well 
  as 
  to 
  consider 
  the 
  many 
  structural 
  characters 
  which 
  may 
  come 
  

   under 
  observation. 
  Several 
  writers 
  have 
  insisted 
  upon 
  a 
  knowledge 
  

   of 
  the 
  fossil 
  Mollusca 
  as 
  a 
  powerful 
  aid 
  in 
  comprehending 
  the 
  liistory 
  

   of 
  existing 
  forms, 
  and 
  it 
  is 
  pleasant 
  in 
  this 
  connection 
  to 
  know 
  that 
  

   our 
  former 
  President, 
  Mr. 
  B. 
  B. 
  Woodward,' 
  in 
  his 
  Address 
  before 
  

   the 
  Society 
  on 
  "Malacology 
  versus 
  Palaeoconchology 
  ", 
  emphasized 
  

   the 
  importance 
  of 
  the 
  subject 
  as 
  bearing 
  upon 
  the 
  phylogenetic 
  

   relationships 
  of 
  modern 
  shells. 
  No 
  information 
  on 
  geological 
  zones 
  

   would 
  be 
  complete 
  without 
  a 
  reference 
  to 
  the 
  eaily 
  work 
  of 
  William 
  

   Smith, 
  who 
  was 
  styled 
  the 
  "Father 
  of 
  English 
  Geology". 
  Smith 
  - 
  

   was 
  the 
  first 
  geologist 
  of 
  this 
  country 
  to 
  properlj^ 
  grasp 
  the 
  fact 
  that 
  

   stratified 
  deposits 
  followed 
  a 
  regular 
  sequential 
  arrangement, 
  and 
  that 
  

   each 
  layer 
  had 
  its 
  distinct 
  fossils 
  which 
  represented 
  the 
  fauna 
  or 
  flora 
  

   at 
  the 
  time 
  of 
  deposition, 
  and 
  from 
  such 
  studies 
  he 
  was 
  able 
  to 
  assert 
  

   that 
  sti'ata 
  were 
  determinable 
  by 
  the 
  organic 
  remains 
  which 
  they 
  

   contained. 
  

  

  Smith's 
  work 
  in 
  this 
  direction 
  was 
  an 
  important 
  advance 
  on 
  our 
  

   previous 
  knowledge, 
  and 
  greatly 
  influenced 
  palgeontological 
  studies 
  in 
  

   this 
  country. 
  It 
  came 
  to 
  be 
  the 
  basis 
  of 
  the 
  complicated 
  zoning 
  

   system 
  of 
  the 
  rocks 
  which 
  at 
  the 
  present 
  day 
  has 
  developed 
  to 
  almost 
  

   a 
  science 
  in 
  itself, 
  with 
  far-reaching 
  results. 
  The 
  varied 
  and 
  abundant 
  

   forms 
  of 
  Mollusca 
  found 
  in 
  the 
  different 
  strata 
  have 
  made 
  them 
  

   valuable 
  indices 
  of 
  age, 
  many 
  of 
  the 
  more 
  characteristic 
  having 
  been 
  

   adopted 
  as 
  names 
  for 
  certain 
  of 
  the 
  geological 
  zones 
  now 
  recognized. 
  

  

  ^ 
  Proc. 
  Malac. 
  See. 
  London, 
  vol. 
  viii, 
  p. 
  66, 
  1908. 
  

   - 
  Strata 
  Identified 
  by 
  Organized 
  Fossils, 
  1816. 
  

  

  