﻿1864.] 
  

  

  BIGSBY 
  MISSING 
  SEDIMENTARY 
  FORMATIONS. 
  

  

  217 
  

  

  son 
  *, 
  the 
  Coal-measures 
  are 
  generally 
  in 
  concordance 
  with 
  the 
  Car- 
  

   boniferous 
  Limestone 
  ; 
  but 
  this 
  is 
  not 
  the 
  case 
  in 
  parts 
  of 
  Bohemia 
  

   and 
  Poland, 
  where 
  great 
  dislocations 
  took 
  place 
  after 
  the 
  deposition 
  

   of 
  the 
  Carboniferous 
  Limestone, 
  ana* 
  before 
  that 
  of 
  the 
  Coal-mea- 
  

   sures. 
  The 
  former 
  of 
  those 
  two, 
  together 
  with 
  the 
  Devonian 
  and 
  

   Silurian 
  rocks, 
  dips 
  at 
  a 
  high 
  angle, 
  while 
  the 
  Coal-measures 
  are 
  

   horizontal. 
  In 
  this 
  unconformity 
  we 
  have 
  a 
  breach 
  and 
  an 
  interval 
  

   of 
  time 
  represented. 
  Sir 
  R. 
  I. 
  Murchison 
  observes 
  that 
  a 
  great 
  

   fracture 
  between 
  the 
  lower 
  and 
  upper 
  divisions 
  of 
  the 
  Carboniferous 
  

   groups 
  extends 
  not 
  only 
  throughout 
  Germany, 
  but 
  through 
  France 
  

   also. 
  Blanks 
  whose 
  roofs 
  are 
  of 
  Carboniferous 
  rocks 
  are 
  numerous, 
  

   because 
  coal-basins 
  are 
  numerous. 
  Dr. 
  Dale 
  Owen 
  f 
  informs 
  us 
  

   that 
  near 
  the 
  eastern 
  limits 
  of 
  Montgomery 
  County, 
  Kentucky, 
  a 
  

   bed 
  of 
  coal 
  rests 
  on 
  a 
  Devonian 
  sandstone 
  (Chemung), 
  the 
  latter 
  

   being 
  on 
  another 
  sandstone 
  full 
  of 
  the 
  Cauda-galli 
  fucoid. 
  In 
  Brit- 
  

   tany 
  J 
  and 
  the 
  west 
  of 
  France 
  the 
  Lower 
  Carboniferous 
  beds 
  are 
  

   in 
  direct 
  superposition 
  to 
  the 
  Lower 
  Devonian; 
  and 
  at 
  Lesma- 
  

   hago 
  § 
  (west 
  of 
  Scotland) 
  the 
  coal-beds 
  repose 
  transgressively 
  on 
  

   several 
  horizons 
  — 
  on 
  the 
  Old 
  Red 
  Sandstone, 
  and 
  Silurian 
  of 
  dif- 
  

   ferent 
  ages. 
  These 
  three 
  conditions 
  arise 
  from 
  distinct 
  crust-move- 
  

   ments. 
  At 
  the 
  mouth 
  of 
  the 
  gorge 
  of 
  L'Echappe, 
  in 
  the 
  valley 
  of 
  

   Firminy, 
  it 
  is 
  interesting 
  to 
  observe 
  that 
  the 
  Carboniferous 
  sand- 
  

   stone, 
  where 
  in 
  contact 
  with 
  the 
  mica-slate, 
  is 
  composed 
  of 
  small 
  

   and 
  often 
  angular 
  fragments 
  of 
  the 
  slate 
  ; 
  thus 
  indicating 
  an 
  in- 
  

   terval 
  of 
  time 
  between 
  their 
  deposition. 
  Their 
  respective 
  dips 
  are 
  

   different 
  ||. 
  

  

  Out 
  of 
  thirty-two 
  instances, 
  from 
  my 
  ordinary 
  note-book, 
  of 
  

   blanks 
  downwards 
  from 
  the 
  Coal-formation, 
  twenty 
  have 
  their 
  base 
  

   on 
  Silurian 
  strata, 
  partly 
  because 
  they 
  are 
  stratigraphically 
  near 
  ; 
  

   but 
  still 
  a 
  blank 
  of 
  great 
  duration 
  is 
  involved. 
  A 
  few 
  instances 
  

   will 
  now 
  be 
  stated, 
  and 
  some 
  of 
  the 
  rest 
  will 
  be 
  referred 
  to 
  in 
  a 
  

   foot-note. 
  

  

  Fig. 
  12. 
  — 
  Section 
  showing 
  Coal-measures 
  lying 
  unconformably 
  on 
  

   Lower 
  Silurian 
  (after 
  Hall 
  and 
  Daniell). 
  

  

  a. 
  Calciferous 
  Sandstone. 
  

  

  b. 
  St. 
  Peter's 
  Sandstone. 
  

  

  c. 
  Trenton 
  Limestone 
  

  

  d. 
  Coal-measures. 
  

  

  Prof. 
  James 
  Hall, 
  of 
  Albany 
  (in 
  a 
  short 
  tract, 
  published 
  separately), 
  

   describes 
  Coal-measures 
  lying 
  unconformably 
  on 
  Trenton 
  Limestone, 
  

  

  * 
  D'Archiac, 
  ' 
  Histoire 
  des 
  Progres,' 
  vol. 
  iii. 
  p. 
  135. 
  

   t 
  G-eol. 
  Surv. 
  Kentucky, 
  4th 
  Report, 
  p. 
  341. 
  

   X 
  Murchison, 
  ' 
  Siluria,' 
  3rd 
  edit. 
  p. 
  441. 
  

   § 
  G-eikie, 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  xvi. 
  p. 
  320. 
  

   j| 
  De 
  Beaumont 
  and 
  Dufrenov, 
  ' 
  Explic. 
  Carte 
  Geol.' 
  vol. 
  i. 
  p. 
  520. 
  

  

  Q2 
  

  

  