﻿440 
  DE. 
  H. 
  HICKS 
  ON 
  THE 
  MORTE 
  SLATES, 
  AND 
  [Aug. 
  1 
  897, 
  

  

  so-called 
  Morte 
  Slates 
  and 
  the 
  Ilfracombe 
  Beds 
  on 
  the 
  north, 
  and 
  

   between 
  the 
  former 
  and 
  the 
  Pickwell 
  Down 
  Beds 
  on 
  the 
  south, 
  are 
  

   probably 
  throughout 
  faulted 
  junctions. 
  Many 
  areas 
  beyond 
  the 
  

   limits 
  of 
  the 
  accompanying 
  map 
  have 
  been 
  examined, 
  but 
  the 
  only 
  

   new 
  evidence 
  of 
  importance 
  from 
  those 
  areas 
  has 
  been 
  the 
  discovery 
  

   of 
  plant- 
  and 
  fish-remains 
  in 
  the 
  Pickwell 
  Down 
  Sandstones, 
  which 
  

   are 
  in 
  contact 
  with 
  the 
  Morte 
  Slates 
  near 
  Baiiinch 
  Abbey 
  in 
  the 
  

   Exe 
  Valley, 
  and 
  of 
  plant-remains 
  in 
  the 
  Hangman 
  Grits 
  at 
  Timbers- 
  

   combe. 
  I 
  must 
  not 
  omit 
  to 
  express 
  my 
  great 
  indebtedness, 
  for 
  

   much 
  valuable 
  information 
  and 
  guidance 
  to 
  localities, 
  to 
  the 
  

   valuable 
  papers 
  on 
  these 
  areas 
  by 
  Mr. 
  R. 
  Etheridge, 
  E.R.S., 
  and 
  

   by 
  Mr. 
  Ussher, 
  E.G.S., 
  of 
  the 
  Geological 
  Survey, 
  and 
  the 
  late 
  

   Mr. 
  Champernowne, 
  E.G.S. 
  

  

  II. 
  The 
  Treborotjgh 
  District. 
  

  

  The 
  line 
  of 
  junction 
  between 
  the 
  so-called 
  Morte 
  Slates 
  and 
  the 
  

   Ilfracombe 
  Beds 
  in 
  this 
  area 
  has 
  been 
  hitherto 
  but 
  imperfectly 
  

   defined, 
  mainly 
  owing 
  to 
  the 
  fact 
  that 
  there 
  is 
  at 
  Treborough 
  a 
  

   fairly 
  thick 
  band 
  of 
  limestone 
  in 
  association 
  with 
  the 
  slates 
  ; 
  for, 
  as 
  

   is 
  well 
  known, 
  it 
  has 
  been 
  generally 
  assumed 
  that 
  the 
  Morte 
  Slates 
  

   in 
  North 
  Devon 
  are 
  entirely 
  devoid 
  of 
  limestone-deposits. 
  1 
  In 
  his 
  

   map 
  (Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  xxiii. 
  1867, 
  p. 
  580) 
  Mr. 
  Etheridge 
  

   gives 
  the 
  line 
  of 
  division 
  as 
  north 
  of 
  Exton, 
  passing 
  by 
  Treborough 
  

   to 
  Monksilver, 
  and 
  at 
  p. 
  602 
  he 
  says 
  : 
  — 
  ' 
  It 
  may 
  be 
  assumed 
  with 
  

   but 
  little 
  hesitation 
  that 
  a 
  line 
  drawn 
  from 
  Lee 
  Bay 
  to 
  Challa- 
  

   combe 
  (north 
  of 
  Bratton 
  Down), 
  Eyeson 
  Hill, 
  and 
  Treborough 
  

   would 
  nearly 
  indicate 
  the 
  marked 
  division 
  that 
  takes 
  place 
  between 
  

   the 
  lower 
  group 
  of 
  slates, 
  with 
  its 
  associated 
  limestones 
  and 
  well- 
  

   marked 
  Middle 
  Devonian 
  fauna, 
  and 
  the 
  higher, 
  pale-grey, 
  glossy, 
  

   unfossiliferous 
  series, 
  accompanied 
  D3 
  7 
  the 
  quartz-veins 
  that 
  form 
  so 
  

   conspicuous 
  a 
  feature 
  at 
  Lee 
  Bay, 
  Bull 
  Point, 
  Rockham 
  Bay, 
  and 
  

   Mortehoe, 
  2 
  and 
  which 
  unmistakably 
  strike 
  from 
  the 
  sea 
  on 
  the 
  west 
  

   to 
  Wiveliscombe 
  on 
  the 
  east, 
  passing 
  north 
  of 
  Bittadon, 
  Arlington, 
  

   Withypool, 
  Winsford, 
  the 
  Exe 
  Yalley, 
  and 
  Exton 
  Hill,' 
  a 
  distance 
  

   in 
  length 
  of 
  over 
  40 
  miles. 
  Mr. 
  Ussher, 
  in 
  his 
  map 
  in 
  the 
  Proceedings 
  

   of 
  the 
  Somersetshire 
  Archaeological 
  & 
  Natural 
  History 
  Society 
  for 
  

   1889 
  (vol. 
  xxxv) 
  has 
  not 
  attempted 
  to 
  separate 
  the 
  Morte 
  Slates 
  

   from 
  the 
  Ilfracombe 
  Beds, 
  merely 
  dividing 
  them 
  as 
  Upper 
  (Morte) 
  

   and 
  Lower 
  (Ilfracombe) 
  Beds 
  in 
  the 
  Middle 
  Devonian, 
  and 
  at 
  p. 
  20 
  

   he 
  says 
  : 
  — 
  ' 
  These 
  slates 
  occupy 
  an 
  area 
  of 
  about 
  90 
  square 
  miles 
  in 
  

   Sheet 
  20. 
  There 
  is 
  even 
  less 
  distinction 
  between 
  the 
  upper 
  and 
  

   lower 
  portions 
  than 
  in 
  the 
  typical 
  districts 
  from 
  which 
  their 
  names 
  

   are 
  derived. 
  The 
  upper 
  part 
  is 
  less 
  evenly 
  fissile 
  than 
  in 
  North. 
  

   Devon, 
  and 
  does 
  not 
  maintain 
  so 
  uniformly 
  its 
  pale 
  green-grey 
  tint. 
  

  

  1 
  It 
  is 
  a 
  mistake 
  to 
  say 
  that 
  there 
  are 
  no 
  limestone-bands 
  in 
  the 
  Morte 
  Slates 
  

   of 
  North 
  Devon, 
  for 
  I 
  have 
  found 
  several, 
  usually 
  in 
  a 
  decomposed 
  state 
  on 
  the 
  

   surface, 
  in 
  Morte 
  Bay, 
  Lee 
  Valley, 
  and 
  elsewhere. 
  

  

  2 
  In 
  the 
  first 
  part 
  of 
  the 
  paper 
  I 
  stated 
  that 
  the 
  quartz-veins 
  so 
  frequently 
  

   seen 
  in 
  the 
  Morte 
  Slates 
  in 
  North 
  Devon 
  occur 
  in 
  fault-lines, 
  and 
  where 
  the 
  

   folds 
  have 
  been 
  much 
  crushed. 
  

  

  