﻿1864.] 
  

  

  BIGSBY 
  — 
  MISSING 
  SEDIMENTARY 
  FORMATIONS. 
  

  

  211 
  

  

  parallel, 
  namely, 
  the 
  Estuarine 
  beds 
  of 
  the 
  Pampas 
  of 
  South 
  America, 
  

   the 
  phosphatic 
  deposit 
  in 
  Bussia, 
  and 
  the 
  deposit 
  of 
  chlorite-earth 
  

   on 
  the 
  south 
  side 
  of 
  Lake 
  Superior 
  ; 
  but 
  the 
  upper 
  and 
  lower 
  lacunae 
  

   brought 
  to 
  light 
  here 
  have 
  no 
  equal 
  in 
  dimensions. 
  The 
  upper 
  is 
  

   bounded 
  by 
  White 
  Chalk 
  and 
  the 
  Oxford 
  Clay,- 
  and 
  the 
  strata 
  

   absent 
  are 
  portions 
  of 
  the 
  Cretaceous 
  series 
  (including 
  all 
  the 
  Neo- 
  

   comian) 
  and 
  much 
  of 
  the 
  Jurassic. 
  The 
  lower 
  gap 
  is 
  made 
  by 
  the 
  

   loss 
  of 
  the 
  Lower 
  Oolite, 
  the 
  Lias, 
  the 
  Trias, 
  and 
  often 
  the 
  Per- 
  

   mian 
  ; 
  the 
  Oxfordian 
  always 
  resting 
  either 
  on 
  Permian 
  or 
  Carboni- 
  

   ferous. 
  The 
  Chalk 
  and 
  the 
  Oxford 
  Clay 
  (the 
  latter 
  being 
  floor 
  and 
  

   roof 
  at 
  the 
  same 
  time) 
  of 
  this 
  great 
  region 
  were 
  therefore 
  above 
  water 
  

   during 
  the 
  deposition 
  elsewhere 
  of 
  the 
  remaining 
  Secondary 
  rocks. 
  

   These 
  remarkable 
  blanks 
  are 
  not 
  so 
  distinct 
  and 
  continuous 
  in 
  Western 
  

   Europe 
  ; 
  for 
  there 
  the 
  Secondary 
  formations 
  are 
  better 
  represented. 
  

   In 
  the 
  Doubs 
  and 
  the 
  Cevennes 
  (France) 
  the 
  Oxford 
  Clay 
  is 
  followed 
  

   normally 
  by 
  the 
  lower 
  rocks 
  ; 
  and 
  in 
  other 
  parts 
  of 
  France 
  it 
  is 
  sup- 
  

   ported 
  by 
  the 
  Great 
  Oolite 
  and 
  other 
  members 
  of 
  the 
  third 
  group 
  *. 
  

  

  The 
  following 
  is 
  only 
  one 
  instance 
  out 
  of 
  many 
  in 
  which 
  the 
  

   great 
  eastern 
  blank 
  is 
  filled 
  up 
  in 
  the 
  west; 
  but 
  as 
  it 
  is 
  very 
  

   striking, 
  it 
  may 
  receive 
  brief 
  notice. 
  It 
  is 
  seen 
  in 
  a 
  section 
  of 
  the 
  

   Jurassic 
  rocks 
  extending 
  from 
  Donzenac 
  f 
  (Department 
  Correze) 
  to 
  

   Sasseginnies 
  (Lot), 
  in 
  the 
  south-west 
  of 
  France. 
  In 
  the 
  interval 
  be- 
  

   tween 
  these 
  two 
  towns 
  seventeen 
  important 
  stages, 
  between 
  Tertiary 
  

   strata 
  and 
  a 
  gneiss, 
  probably 
  Laurentian, 
  succeed 
  each 
  other 
  con- 
  

   formably. 
  These 
  stages 
  represent 
  Chalk, 
  beds 
  belonging 
  to 
  each 
  of 
  

   the 
  three 
  Oolite 
  Groups, 
  four 
  beds 
  of 
  Lias, 
  Keuper 
  and 
  red 
  clay 
  of 
  

   the 
  Trias, 
  two 
  Carboniferous 
  beds, 
  a 
  roofing-slate 
  (Silurian 
  ?), 
  mica- 
  

   slate, 
  and, 
  lastly, 
  gneiss. 
  

  

  a. 
  Oolite. 
  — 
  I 
  will 
  now 
  mention 
  some 
  of 
  the 
  blanks 
  which 
  begin 
  

   at 
  the 
  Oolite, 
  as 
  a 
  few 
  out 
  of 
  the 
  many 
  ; 
  my 
  difficulty 
  throughout 
  

   this 
  paper 
  being 
  not 
  to 
  overload 
  the 
  subject. 
  

  

  Fig. 
  6. 
  — 
  Section 
  near 
  Albarasin, 
  between 
  Madrid 
  and 
  Alicante, 
  show- 
  

   ing 
  Oxford 
  Clay 
  resting 
  on 
  Lias, 
  and 
  Trias 
  on 
  Silurian 
  (after 
  M. 
  

   Collomb). 
  

  

  k 
  

  

  d. 
  Oxford 
  Clay. 
  

  

  e. 
  Lias. 
  

  

  h. 
  Clay 
  and 
  Gypsum 
  (Trias). 
  

  

  i. 
  Muschelkalk. 
  

  

  k. 
  Bunter 
  Sandstone. 
  

  

  m. 
  Silurian. 
  

  

  M. 
  Triger 
  % 
  gives 
  a 
  large 
  and 
  beautiful 
  section 
  from 
  near 
  Mans, 
  

   which 
  tells 
  us 
  of 
  the 
  absence 
  of 
  the 
  Great 
  Oolite, 
  and 
  of 
  a 
  vast 
  gap 
  

   from 
  the 
  Lias-marls 
  down 
  to 
  the 
  schists 
  of 
  the 
  Lower 
  Silurian. 
  

  

  * 
  D'Archiac, 
  ' 
  Histoire 
  des 
  Progres,' 
  vol. 
  vi.p. 
  464. 
  

  

  t 
  Ibid. 
  vol. 
  iv. 
  pi. 
  2. 
  fig. 
  1. 
  

  

  X 
  Bull. 
  Soc. 
  Geol. 
  de 
  France, 
  2 
  e 
  serie, 
  vol. 
  vii. 
  p. 
  762. 
  

  

  