﻿1864.] 
  BIGSBY 
  MISSING 
  SEDIMENTARY 
  FORMATIONS. 
  205 
  

  

  vast. 
  Thus, 
  following 
  the 
  Chalk-beds 
  from 
  west 
  to 
  east, 
  from 
  the 
  

   eastern 
  frontiers 
  of 
  Gallicia 
  and 
  Podolia 
  to 
  the 
  south 
  end 
  of 
  the 
  

   Oural 
  Mountains, 
  we 
  have 
  30° 
  of 
  longitude, 
  and 
  from 
  north 
  to 
  south, 
  

   from 
  Simbirsk 
  to 
  Orenburg, 
  nearly 
  7° 
  of 
  latitude. 
  Throughout 
  

   the 
  whole 
  of 
  this 
  space 
  we 
  have 
  only 
  the 
  White 
  Chalk, 
  and 
  it 
  is 
  

   never 
  more 
  than 
  300 
  feet 
  thick 
  ; 
  and 
  in 
  Russia 
  it 
  lies 
  exclusively 
  

   on 
  Oxford 
  Clay, 
  Kimmeridge 
  Clay, 
  and 
  Portland 
  Stone 
  — 
  a 
  fact 
  of 
  

   great 
  interest. 
  The 
  highly 
  fossiliferous 
  chalk 
  of 
  Trichinopoly 
  and 
  

   South 
  Arcot 
  is 
  subdivided 
  by 
  Mr. 
  H. 
  T. 
  Blanford 
  * 
  into 
  six 
  groups 
  ; 
  

   and 
  some 
  of 
  these 
  are 
  often 
  missing. 
  

  

  a. 
  Chalk. 
  — 
  The 
  following 
  instances 
  of 
  blanks 
  occurring 
  from 
  be- 
  

   neath 
  the 
  Chalk 
  might 
  be 
  multiplied 
  almost 
  indefinitely. 
  Very 
  many 
  

   more 
  are 
  implied 
  in 
  the 
  blanks 
  treated 
  of 
  under 
  other 
  epochs. 
  In 
  

   most 
  cases 
  the 
  area 
  is 
  considerable, 
  and 
  reaches 
  to 
  many 
  hundreds 
  

   or 
  thousands 
  of 
  square 
  miles. 
  

  

  The 
  Cretaceous 
  rocks 
  in 
  England 
  are 
  always 
  unconformable 
  to 
  

   the 
  Oolitic 
  t, 
  with 
  considerable 
  denudation 
  of 
  the 
  latter, 
  as 
  in 
  Ox- 
  

   fordshire 
  (Prof. 
  Phillips). 
  There 
  is, 
  therefore, 
  a 
  hiatus 
  between 
  

   them. 
  

  

  According 
  to 
  Mr. 
  Darwin 
  X, 
  Upper 
  Cretaceous 
  rocks 
  lie 
  on 
  Jurassic 
  

   strata 
  in 
  the 
  Chilian 
  Andes, 
  Neocomian 
  beds 
  being 
  absent 
  ; 
  and 
  at 
  

   Coquimbo 
  and 
  other 
  places 
  Cretaceous 
  and 
  Jurassic 
  fossils 
  are 
  inter- 
  

   mingled 
  in 
  the 
  same 
  beds, 
  from 
  which 
  it 
  is 
  inferred 
  that 
  the 
  passage 
  

   has 
  been 
  gradual, 
  and 
  that 
  there 
  has 
  been 
  no 
  gap. 
  On 
  Lake 
  Tiberius 
  § 
  

   and 
  about 
  the 
  Dead 
  Sea, 
  in 
  Palestine, 
  in 
  the 
  Duchy 
  of 
  Brunswick 
  ||, 
  on 
  

   the 
  north 
  flank 
  of 
  the 
  Hartz, 
  Chalk 
  covers 
  Lower 
  Jurassic 
  strata 
  ^[; 
  

   while 
  in 
  the 
  plains 
  of 
  Poland, 
  Gallicia, 
  and 
  Yolhynia 
  it 
  lies 
  horizon- 
  

   tally 
  on 
  the 
  newest 
  Jurassic. 
  In 
  the 
  Department 
  of 
  the 
  Yar 
  ** 
  this 
  

   rock 
  caps 
  Jurassic 
  strata, 
  which 
  latter 
  are 
  incumbent 
  on 
  Bunter 
  

   Sandstone. 
  

  

  In 
  Yorkshire 
  this 
  formation 
  rests 
  both 
  upon 
  Lias 
  and 
  upon 
  the 
  

   curved 
  and 
  inclined 
  beds 
  of 
  Xew 
  Red 
  Sandstone 
  ft 
  (Trias). 
  Casiano 
  

   de 
  Prado 
  t+ 
  found 
  it, 
  in 
  the 
  province 
  of 
  Segovia, 
  to 
  lie, 
  by 
  overlap, 
  

   successively 
  on 
  Trias, 
  Silurian, 
  Gneiss, 
  and 
  Granite, 
  all 
  deeply 
  

   denuded. 
  

  

  M. 
  Ivanitski 
  §§ 
  met 
  with 
  Chalk 
  lying 
  directly 
  on 
  Keuper 
  at 
  

   Bakhmoutha 
  (Donetz, 
  Russia) 
  ; 
  and 
  nearly 
  the 
  same 
  thing 
  occurs 
  

   at 
  Jumilla, 
  in 
  Spain, 
  as 
  we 
  learn 
  from 
  a 
  fine 
  section 
  in 
  the 
  Salines 
  

   of 
  Rosa 
  || 
  || 
  . 
  

  

  Chalk 
  overlies 
  Upper 
  Carboniferous 
  Limestone 
  unconformably 
  in 
  

  

  * 
  Palseontologia 
  Indica, 
  toI. 
  i. 
  p. 
  v. 
  

   t 
  Jukes, 
  ' 
  Manual 
  of 
  Geology,' 
  pp. 
  620, 
  621. 
  

   X 
  Bull. 
  Soc. 
  Geol. 
  de 
  France, 
  2 
  e 
  serie, 
  vol. 
  iv. 
  p. 
  508. 
  

   § 
  D'Archiac, 
  ' 
  Histoire 
  des 
  Progres,' 
  vol. 
  v. 
  p. 
  388. 
  

   || 
  Ibid. 
  vol. 
  vii. 
  p. 
  511. 
  ' 
  % 
  Ibid. 
  vol. 
  v. 
  p. 
  334. 
  

  

  ** 
  Ibid. 
  vol. 
  vi. 
  p. 
  556. 
  tt 
  Lyell, 
  'Principles,' 
  p. 
  187. 
  

  

  XX 
  Bull. 
  Soc. 
  Geol. 
  de 
  France, 
  2 
  e 
  serie, 
  vol. 
  xi. 
  p. 
  337. 
  

   §§ 
  D'Archiac, 
  ' 
  Histoire 
  des 
  Progres,' 
  vol. 
  viii. 
  p. 
  567. 
  

  

  HII 
  De 
  Yerneuil 
  and 
  Collonib, 
  Bull. 
  Soc. 
  Geol. 
  de 
  France, 
  2 
  C 
  serie. 
  vol. 
  xiii. 
  

   pp. 
  677, 
  683. 
  

  

  