﻿102 
  ME. 
  F. 
  K. 
  COWPEE 
  EEED 
  ON 
  THE 
  [Feb. 
  1 
  897, 
  

  

  has 
  suffered 
  enormous 
  denudation, 
  leading 
  to 
  its 
  complete 
  removal 
  

   except 
  in 
  this 
  one 
  spot. 
  Since 
  everyone 
  must 
  concede, 
  even 
  from 
  

   the 
  above 
  evidence 
  of 
  the 
  fossils, 
  that 
  the 
  fauna 
  has 
  an 
  Ordovician 
  

   facies, 
  we 
  look 
  down 
  the 
  list 
  of 
  Ordovician 
  rocks 
  of 
  the 
  district 
  to 
  

   see 
  at 
  what 
  horizon 
  it 
  can 
  be 
  inserted. 
  But 
  there 
  is 
  no 
  gap 
  in 
  

   the 
  series 
  or 
  trace 
  of 
  such 
  a 
  widespread 
  denudation, 
  at 
  any 
  rate 
  

   until 
  we 
  come 
  to 
  the 
  top 
  of 
  the 
  system, 
  and 
  at 
  this 
  point 
  a 
  difficulty 
  

   arises, 
  for 
  the 
  authorities 
  on 
  this 
  district 
  are 
  divided 
  in 
  their 
  

   opinions. 
  

  

  Marr 
  & 
  Nicholson 
  * 
  do 
  not 
  mention 
  any 
  break 
  between 
  the 
  Ordo- 
  

   vician 
  and 
  Silurian, 
  but 
  have 
  traced 
  the 
  whole 
  series 
  in 
  unbroken 
  

   succession 
  from 
  the 
  rhyolite 
  and 
  ashes 
  below 
  the 
  Corona-beds 
  up 
  

   into 
  the 
  Brathay 
  Flags, 
  which 
  are 
  of 
  Wenlock 
  Shale 
  age. 
  

  

  The 
  first-named 
  author 
  2 
  moreover 
  states 
  that 
  he 
  has 
  not 
  detected 
  

   any 
  traces 
  of 
  the 
  supposed 
  denudation 
  at 
  the 
  close 
  of 
  Ordovician 
  

   times 
  in 
  this 
  area, 
  and 
  certainly 
  if 
  it 
  really 
  exists, 
  the 
  evidence 
  of 
  it 
  

   has 
  not 
  yet 
  been 
  published. 
  In 
  the 
  Lake 
  District, 
  however, 
  there 
  

   is 
  a 
  physical 
  break 
  between 
  the 
  Ashgill 
  Shales 
  and 
  the 
  overlying 
  

   series, 
  which 
  is 
  marked 
  in 
  various 
  localities 
  by 
  the 
  well-known 
  

   conglomerate 
  with 
  Meristella 
  (?) 
  crassa. 
  The 
  great 
  irregularity 
  in 
  

   the 
  thickness 
  of 
  the 
  Ashgill 
  Shales 
  in 
  that 
  district 
  is 
  to 
  be 
  attributed 
  

   either 
  to 
  an 
  overlap 
  of 
  the 
  overlying 
  strata 
  or 
  to 
  an 
  unconformity, 
  

   and 
  several 
  facts 
  seem 
  more 
  in 
  favour 
  of 
  the 
  latter. 
  3 
  

  

  Mr. 
  Goodchild 
  4 
  is 
  the 
  main 
  upholder 
  of 
  the 
  denudation-theory 
  in 
  

   the 
  Cross 
  Fell 
  area, 
  and 
  he 
  disputes 
  the 
  continuity 
  of 
  deposition 
  

   from 
  Ordovician 
  into 
  Silurian 
  times. 
  Roughly 
  dividing 
  the 
  Bala 
  

   rocks 
  of 
  the 
  Cross 
  Fell 
  inlier 
  into 
  a 
  lower 
  ' 
  calcareous 
  shale 
  ' 
  

   series 
  and 
  an 
  upper 
  ' 
  mainly 
  calcareous 
  ' 
  series 
  graduating 
  into 
  

   each 
  other, 
  he 
  says 
  : 
  — 
  ' 
  The 
  limestone 
  of 
  Keisley 
  belongs, 
  I 
  believe, 
  

   to 
  a 
  higher 
  part 
  of 
  this 
  calcareous 
  series 
  than 
  has 
  been 
  left 
  by 
  pre- 
  

   Silurian 
  denudation 
  elsewhere 
  in 
  the 
  area 
  under 
  notice.' 
  

  

  If, 
  however, 
  we 
  can 
  show 
  that 
  the 
  palaeontological 
  affinities 
  of 
  

   the 
  bed 
  are 
  not 
  with 
  the 
  Ashgill 
  Shales, 
  but 
  with 
  beds 
  below 
  them, 
  

   we 
  shall 
  be 
  forced 
  on 
  these 
  grounds 
  alone 
  to 
  reject 
  the 
  theory 
  that 
  

   the 
  limestone 
  is 
  the 
  remnant 
  of 
  a 
  bed 
  at 
  the 
  very 
  top 
  of 
  the 
  Ordo- 
  

   vician 
  System, 
  unless, 
  indeed, 
  we 
  .betake 
  ourselves 
  to 
  Barrande's 
  

   theory 
  of 
  colonies. 
  Mr. 
  Goodchild 
  (loc. 
  cit.) 
  admits 
  that 
  the 
  patch 
  

   of 
  limestone 
  is 
  faulted-in 
  all 
  round, 
  so 
  that 
  its 
  relations 
  to 
  other 
  

   beds 
  cannot 
  be 
  directly 
  observed, 
  but 
  only 
  inferred. 
  

  

  In 
  a 
  case, 
  therefore, 
  such 
  as 
  this, 
  the 
  determination 
  of 
  the 
  exact 
  

   horizon 
  must 
  be 
  made 
  entirely 
  from 
  the 
  evidence 
  of 
  the 
  fossils 
  and 
  

   the 
  affinities 
  of 
  the 
  fauna. 
  

  

  1 
  Quart. 
  Joura. 
  Geol. 
  Soc. 
  vol. 
  xlvii. 
  (1891) 
  p. 
  500, 
  and 
  Geol. 
  Mag. 
  1892, 
  

   p. 
  97. 
  

  

  2 
  Geol. 
  Mag. 
  1892, 
  p. 
  445. 
  

  

  3 
  Marr, 
  Quart, 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  xxxiv. 
  (1878) 
  p. 
  871 
  ; 
  T. 
  M 
  C 
  K. 
  Hughes, 
  

   Geol. 
  Mag. 
  1807, 
  p. 
  354; 
  Aveline, 
  Geol. 
  Mag. 
  1872, 
  p. 
  441, 
  and 
  ibid. 
  1876, 
  

   p. 
  282. 
  

  

  4 
  Geol. 
  Mag. 
  1892, 
  p. 
  295. 
  

  

  