﻿1864.] 
  BIGSBY 
  MISSIXG 
  SEDlXEXTARr 
  FORMATIONS. 
  231 
  

  

  the 
  effects 
  of 
  the 
  elements 
  and 
  of 
  time, 
  are 
  obvious 
  ; 
  so 
  that, 
  without 
  

   dwelling 
  on 
  them, 
  I 
  will 
  proceed 
  to 
  remark 
  on 
  the 
  various 
  posi- 
  

   tions 
  they 
  assume 
  towards 
  each 
  other. 
  These 
  relations 
  have 
  been 
  

   stated 
  by 
  the 
  original 
  observers 
  in 
  fifty-two 
  cases, 
  and 
  they 
  have 
  

   been 
  now 
  collected, 
  for 
  examination 
  and 
  use, 
  into 
  the 
  form 
  of 
  a 
  

   Table 
  (B), 
  which 
  contains 
  their 
  locality, 
  the 
  horizon 
  which 
  they 
  

   occupy, 
  the 
  authority, 
  and, 
  lastly, 
  the 
  positions 
  of 
  basement 
  and 
  roof. 
  

  

  Table 
  B 
  shows 
  that 
  all 
  the 
  gaps 
  are 
  the 
  products 
  of 
  disturbance. 
  

   In 
  the 
  six 
  cases 
  where 
  the 
  top 
  and 
  bottom 
  strata 
  are 
  at 
  the 
  same 
  time 
  

   conformable 
  and 
  inclined, 
  the 
  force 
  must 
  have 
  been 
  exerted 
  obliquely 
  

   and 
  over 
  a 
  large 
  area 
  (Texas 
  to 
  Missouri). 
  In 
  the 
  seven 
  cases 
  where 
  

   they 
  are 
  both 
  horizontal, 
  the 
  movement 
  must 
  have 
  been 
  vertical, 
  and 
  

   have 
  affected 
  a 
  considerable 
  region. 
  In 
  the 
  twenty-two 
  cases 
  where 
  

   the 
  roof 
  is 
  unconformable 
  to 
  the 
  floor, 
  and 
  both 
  are 
  inclined, 
  there 
  

   must 
  have 
  been 
  more 
  uplifts 
  than 
  one 
  — 
  an 
  action 
  that 
  has 
  give 
  a 
  rise 
  

   to 
  the 
  " 
  complex 
  mountains 
  " 
  of 
  Sismonda 
  and 
  Studer. 
  

  

  In 
  seventeen 
  cases 
  the 
  floor 
  is 
  inclined 
  and 
  the 
  roof 
  is 
  horizontal. 
  

   Here 
  the 
  former 
  represents 
  disturbance 
  ; 
  the 
  latter, 
  quiet 
  deposition 
  

   long 
  afterwards. 
  Two 
  other 
  columns 
  might 
  have 
  been 
  given, 
  but 
  

   are 
  omitted 
  because 
  it 
  is 
  impossible 
  for 
  the 
  condition 
  to 
  occur 
  which 
  

   they 
  would 
  represent, 
  namely, 
  for 
  the 
  roof 
  of 
  a 
  gap 
  to 
  be 
  inclined 
  

   when 
  its 
  base 
  is 
  horizontal 
  ; 
  for 
  all 
  upheavals 
  are 
  caused 
  by 
  a 
  force 
  

   acting 
  from 
  below. 
  

  

  These 
  gaps 
  or 
  blanks 
  are 
  local, 
  both 
  in 
  their 
  origin 
  and 
  in 
  their 
  

   effects, 
  because 
  oscillation, 
  their 
  governing 
  cause, 
  is 
  itself 
  local 
  and 
  

   dependent 
  on 
  laws 
  as 
  yet 
  undiscovered. 
  Observation 
  in 
  the 
  field 
  has 
  

   demonstrated 
  that 
  perturbation 
  is 
  local. 
  We 
  see 
  this 
  in 
  the 
  alter- 
  

   nately 
  fresh 
  and 
  marine 
  deposits 
  of 
  Tertiary 
  and 
  Carboniferous 
  times 
  ; 
  

   and 
  even 
  in 
  the 
  celebrated 
  disturbance 
  on 
  the 
  Biver 
  Onny 
  (X.Wales), 
  

   where 
  the 
  unconformity 
  vanishes 
  near 
  at 
  hand 
  ; 
  and, 
  furthermore, 
  

   we 
  see 
  it 
  in 
  the 
  Trias 
  of 
  Tuscany 
  lying 
  on 
  Yerrucano 
  (Carboniferous), 
  

   at 
  the 
  baths 
  of 
  San 
  Julio 
  and 
  elsewhere. 
  

  

  If 
  crust-movements 
  be 
  local, 
  so 
  also 
  is 
  the 
  deposit 
  of 
  sediment, 
  in 
  

   its 
  details, 
  with 
  epochal 
  specialities. 
  To 
  these 
  conclusions 
  Elie 
  de 
  

   Beaumont*, 
  Murchisont, 
  Edward 
  Forbes 
  j, 
  John 
  Phillips 
  §, 
  Bar- 
  

   rande 
  : 
  , 
  D'Archiac, 
  and 
  others 
  have 
  arrived. 
  

  

  With 
  such 
  mere 
  outlines 
  as 
  the 
  foregoing, 
  we 
  must 
  now 
  rest 
  on 
  

   the 
  great 
  subject 
  of 
  " 
  leaves 
  torn 
  out 
  from 
  nature's 
  volume," 
  as 
  

   speaks 
  " 
  the 
  old 
  man 
  eloquent 
  " 
  of 
  Cambridge, 
  begging 
  permission, 
  

   however, 
  in 
  conclusion, 
  to 
  add 
  a 
  few 
  considerations 
  on 
  the 
  im- 
  

   portance 
  of 
  missing 
  formations. 
  

  

  1. 
  They 
  constitute 
  a 
  breach 
  in 
  normal 
  stratigraphic 
  sequence 
  

   resulting 
  from 
  plutonic 
  influences 
  — 
  influences 
  which, 
  although 
  

   worthy 
  of 
  the 
  most 
  serious 
  consideration, 
  have 
  hitherto 
  received 
  

   little 
  notice, 
  save 
  from 
  Mr. 
  Hopkins 
  and 
  Sir 
  J. 
  Herschel. 
  

  

  Some 
  idea 
  of 
  their 
  frequency 
  and 
  extent 
  may 
  be 
  gathered 
  from 
  

  

  * 
  Bull. 
  Soc. 
  Geol. 
  France, 
  2 
  e 
  serie, 
  vol. 
  xi. 
  p. 
  315. 
  

  

  f 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  v. 
  p. 
  625 
  ; 
  vol. 
  vii. 
  p. 
  18 
  ; 
  vol. 
  viii. 
  pp. 
  180, 
  191. 
  

   % 
  Ibid. 
  vol. 
  x. 
  pp. 
  77, 
  78. 
  § 
  Geol. 
  Surrey 
  Memoirs, 
  vol. 
  i. 
  p. 
  144. 
  

  

  || 
  Bull. 
  Soc. 
  Geol. 
  France, 
  2 
  C 
  serie, 
  vol. 
  xi. 
  p. 
  311. 
  

   VOL. 
  XX. 
  PART 
  I. 
  R 
  

  

  