﻿46 
  

  

  Section 
  11. 
  — 
  Deccan 
  Trap. 
  

   With 
  the 
  most 
  profound 
  respect 
  for 
  the 
  labors 
  of 
  those 
  who 
  are 
  

  

  endeavouring 
  to 
  establish 
  some 
  order 
  in 
  the 
  

  

  Use 
  of 
  the 
  word 
  trap. 
  . 
  

  

  nomenclature 
  01 
  eruptive 
  rocks, 
  and 
  to 
  ascertain 
  

  

  what 
  geological 
  significance 
  may 
  attach 
  to 
  their 
  leading 
  types, 
  it 
  seems 
  

   necessary 
  to 
  enter 
  a 
  protest 
  against 
  their 
  too 
  sweeping 
  condemnation 
  of 
  

   a 
  term 
  in 
  familiar 
  use. 
  "Whatever 
  success 
  may 
  ultimately 
  reward 
  such 
  

   researches, 
  it 
  is 
  pretty 
  certain 
  we 
  can 
  never 
  dispense 
  with 
  so 
  convenient 
  

   a 
  term 
  as 
  trap, 
  in 
  the 
  sense 
  at 
  present 
  attached 
  to 
  it. 
  However 
  convinced 
  

   we 
  may 
  be 
  a 
  priori 
  that 
  eruptive 
  rocks 
  in 
  their 
  composition 
  and 
  texture 
  

   do 
  bear 
  the 
  stamp 
  of 
  the 
  conditions 
  to 
  which 
  they 
  owe 
  their 
  origin, 
  we 
  

   must 
  not 
  be 
  too 
  hasty 
  to 
  adopt 
  the 
  systems 
  elaborated 
  from 
  the 
  very 
  

   imperfect 
  information 
  we 
  possess 
  upon 
  this 
  most 
  obscure 
  subject. 
  Geolo- 
  

   gists 
  will 
  ever 
  object 
  to 
  the 
  introduction 
  of 
  distinct 
  names 
  for 
  identical 
  

   rocks 
  differing 
  only 
  in 
  the 
  age 
  of 
  their 
  eruption, 
  as 
  has 
  been 
  proposed 
  by 
  

   some 
  distinguished 
  vulcanists. 
  The 
  word 
  'trap' 
  has 
  been 
  objected 
  to 
  by 
  

   too 
  exclusive 
  classifiers 
  as 
  unscientific, 
  because 
  clubbing 
  together 
  rocks 
  of 
  

   very 
  different 
  aspect, 
  age, 
  and 
  mode 
  of 
  occurrence. 
  It 
  is 
  with 
  full 
  

   knowledge 
  and 
  due 
  appreciation 
  of 
  all 
  these 
  important 
  distinctions 
  that 
  

   ceolo<nsts 
  adhere 
  to 
  the 
  general 
  term 
  'trap' 
  to 
  denote 
  all 
  lava-oid 
  rocks, 
  

   whether 
  intrusive 
  or 
  overflowing 
  — 
  those 
  rocks 
  which 
  from 
  their 
  com- 
  

   plete 
  analogy 
  with 
  the 
  ejections 
  of 
  actual 
  volcanoes 
  we 
  know 
  certainly 
  

   to 
  be 
  of 
  igneous 
  origin. 
  It 
  would 
  be 
  as 
  reasonable 
  to 
  object 
  to 
  the 
  use 
  

   of 
  the 
  word 
  sandstone 
  ; 
  nay 
  more 
  so, 
  for 
  the 
  several 
  types 
  of 
  sandstone 
  

   do 
  convey 
  definite 
  information 
  regarding 
  the 
  nature 
  of 
  the 
  conditions 
  

   of 
  deposition, 
  whereas 
  we 
  are 
  very 
  far 
  from 
  having 
  like 
  certain 
  informa- 
  

   tion 
  regarding 
  the 
  products 
  of 
  eruption. 
  Yet 
  there 
  is 
  no 
  ambiguity 
  in 
  

   the 
  use 
  of 
  the 
  word 
  sandstone. 
  It 
  would 
  rather 
  be 
  convenient 
  if 
  we 
  

   had 
  a 
  short 
  term 
  to 
  stand 
  for 
  sedimentary 
  rock, 
  as 
  trap 
  does 
  for 
  the 
  

   products 
  of 
  bygone 
  eruptive 
  action. 
  The 
  object 
  of 
  this 
  paper 
  being 
  

   purely 
  stratigraphical, 
  it 
  is 
  sufficient 
  to 
  notice 
  that 
  the 
  trap 
  here 
  is 
  of 
  

   the 
  basaltic 
  family. 
  

   ( 
  178 
  ) 
  ' 
  

  

  