﻿200 
  

  

  PROCEEDINGS 
  OF 
  THE 
  GEOLOGICAL 
  SOCIETY. 
  [Mar. 
  9, 
  

  

  the 
  earth's 
  crust 
  ; 
  and 
  the 
  work 
  is 
  still 
  going 
  on. 
  It 
  is 
  not 
  a 
  thing 
  

   of 
  the 
  past 
  only 
  ; 
  but 
  the 
  ocean-bottom, 
  parcelled 
  out 
  like 
  the 
  dry 
  

   land 
  into 
  geological 
  districts, 
  is 
  still 
  receiving 
  accessions 
  from 
  animal 
  

   debris 
  and 
  insoluble 
  matter 
  suspended 
  in 
  its 
  waters. 
  

  

  The 
  Sections, 
  Figs. 
  1 
  & 
  2, 
  I 
  owe 
  to 
  Messrs. 
  De 
  Verneuil 
  and 
  

   Collomb 
  ; 
  and 
  they 
  form 
  one 
  - 
  of 
  the 
  results 
  of 
  their 
  very 
  extensive 
  

   and 
  methodical 
  investigation 
  into 
  the 
  geology 
  of 
  Spain. 
  They 
  exhibit 
  

   the 
  structure 
  of 
  a 
  region, 
  150 
  miles 
  long, 
  overspread 
  by 
  great 
  blanks, 
  

   which, 
  for 
  our 
  purpose, 
  is 
  sufficiently 
  explained 
  by 
  the 
  sections 
  them- 
  

   selves, 
  which 
  are 
  placed 
  here 
  in 
  proof 
  of 
  the 
  importance 
  of 
  our 
  subject. 
  

  

  Fig. 
  2. 
  — 
  Section 
  of 
  the 
  Sierra 
  Moreno, 
  {Spain), 
  shoiving 
  two 
  great 
  

   Blanks 
  in 
  succession 
  (after 
  MM. 
  de 
  Verneuil 
  and 
  Collomb). 
  

  

  N 
  

  

  Villanueva. 
  

  

  Rio 
  

   Guadarmena. 
  Alcaraz. 
  

  

  Vianos. 
  

  

  a. 
  Silurian. 
  

  

  b. 
  Red 
  sandstone 
  and 
  variegated 
  clay 
  (Trias). 
  

  

  c. 
  Muschelkalk. 
  

  

  d. 
  Calcaire 
  Grossier. 
  

  

  From 
  an 
  abundant 
  supply 
  of 
  instances 
  of 
  blanks 
  (the 
  indications 
  

   of 
  an 
  emerged 
  surface) 
  those 
  described 
  in 
  this 
  memoir 
  have 
  been 
  

   selected, 
  as 
  apt 
  to 
  our 
  purpose, 
  and 
  having 
  an 
  ascertained 
  horizon. 
  

   They 
  are 
  given 
  in 
  descending 
  order, 
  each 
  successive 
  epoch 
  supplying 
  

   the 
  roof 
  of 
  a 
  blank. 
  

  

  II. 
  Instances 
  of 
  Blanks 
  or 
  Gaps. 
  

  

  1 
  . 
  With 
  a 
  Quaternary 
  Roof. 
  — 
  Throughout 
  by 
  far 
  the 
  greater 
  part 
  

   of 
  the 
  extensive 
  countries 
  of 
  Norway, 
  Lapland, 
  Sweden, 
  and 
  Finland, 
  

   Quaternary 
  Diluvium 
  and 
  Northern 
  Drift 
  lie 
  directly 
  on 
  Laurentian 
  

   and 
  Huronian 
  rocks 
  ; 
  little 
  or 
  no 
  deposition 
  having 
  taken 
  place 
  there 
  

   (through 
  25° 
  of 
  longitude 
  and 
  13° 
  of 
  latitude) 
  during 
  the 
  vast 
  in- 
  

   terval 
  of 
  time 
  between 
  that 
  of 
  the 
  contiguous 
  formations. 
  Marks 
  of 
  

   denudation 
  are 
  many 
  and 
  powerful 
  here 
  ; 
  and 
  though 
  there 
  are 
  

   patches 
  of 
  younger 
  strata, 
  they 
  do 
  not 
  require 
  notice 
  from 
  us. 
  

  

  On 
  the 
  opposite 
  coast 
  of 
  North 
  America 
  all 
  this 
  is 
  repeated, 
  

   through 
  Labrador 
  and 
  Canada 
  to 
  beyond 
  the 
  Upper 
  Mississippi 
  River, 
  

   in 
  a 
  broad 
  belt 
  of 
  rugged 
  land 
  2000 
  miles 
  long, 
  where 
  no 
  Mesozoic 
  

   nor 
  old 
  Tertiary 
  rocks, 
  loose 
  or 
  fixed, 
  have 
  been 
  met 
  with, 
  though 
  

   often 
  looked 
  for. 
  From 
  this 
  block 
  of 
  older 
  metamorphic 
  formations 
  

   another 
  broad 
  band 
  of 
  the 
  same 
  antiquity, 
  sprinkled 
  with 
  sand, 
  

   gravel, 
  and 
  boulders, 
  runs 
  from 
  Lake 
  Superior 
  into 
  the 
  Arctic 
  Ocean, 
  

   through 
  Eupert's 
  Land, 
  for 
  1500 
  miles*. 
  Messrs. 
  Foster 
  and 
  Whit- 
  

   ney 
  also 
  remark 
  that 
  " 
  Between 
  the 
  Northern 
  Drift 
  of 
  the 
  south 
  

   side 
  of 
  Lake 
  Superior 
  and 
  the 
  Devonian 
  there 
  are 
  no 
  deposits, 
  but 
  

  

  * 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  xi. 
  p. 
  500. 
  

  

  