﻿184 
  D. 
  MACKINTOSH 
  ON 
  HIGH-LEVEL 
  

  

  18. 
  Additional 
  Discoveries 
  of 
  High-level 
  Marine 
  Drifts 
  in 
  North 
  

   Wales, 
  witli 
  Remarks 
  on 
  Driftless 
  Areas. 
  By 
  D. 
  Mackintosh, 
  

   Esq., 
  F.G.S 
  * 
  (Read 
  February 
  22, 
  1882.) 
  

  

  Contents. 
  

  

  I. 
  Introductory 
  Remarks. 
  

   II. 
  Extent 
  of 
  the 
  Drift-zone 
  between 
  Minera 
  and 
  Llangollen 
  Vale. 
  

   III. 
  Detailed 
  Description. 
  

   IV. 
  Probable 
  Origin 
  of 
  Drift-kuolls. 
  

   V. 
  Driftless 
  areas 
  in 
  North 
  Wales. 
  

   VI. 
  Boulders 
  and 
  Drifts 
  on 
  Moel 
  Wnion. 
  

   VII. 
  Summary 
  of 
  Facts 
  and 
  Inferences. 
  

  

  1. 
  Introductory 
  Remarks. 
  

  

  Since 
  commencing 
  this 
  branch 
  of 
  geological 
  research, 
  I 
  have 
  

   found 
  the 
  subject 
  increasingly 
  beset 
  with 
  difficulties, 
  which 
  have 
  

   chiefly 
  arisen 
  from 
  the 
  necessity 
  for 
  exploring 
  new 
  ground 
  at 
  the 
  

   risk 
  of 
  being 
  frequently 
  disappointed. 
  Since 
  my 
  last 
  paper 
  f 
  was 
  

   written, 
  I 
  have 
  not 
  succeeded 
  in 
  discovering 
  any 
  very 
  decided 
  

   traces 
  of 
  high-level 
  marine 
  drifts 
  in 
  entirely 
  new 
  localities 
  ; 
  and 
  

   though 
  some 
  may 
  have 
  escaped 
  my 
  notice, 
  there 
  can, 
  I 
  believe, 
  be 
  

   little 
  doubt 
  that 
  the 
  drift-zone 
  between 
  Minera 
  and 
  Llangollen 
  

   Yale 
  contains 
  such 
  an 
  immense 
  development 
  of 
  undoubted 
  sea- 
  

   beach 
  deposits, 
  compared 
  with 
  other 
  districts, 
  as 
  to 
  render 
  it 
  worthy 
  

   of 
  a 
  more 
  detailed 
  description 
  than 
  that 
  contained 
  in 
  my 
  last 
  paper, 
  

   more 
  especially 
  since 
  I 
  have 
  succeeded 
  in 
  tracing 
  its 
  extension 
  

   southwards 
  over 
  an 
  additional 
  two 
  miles 
  (see 
  Map, 
  fig. 
  1 
  ). 
  The 
  total 
  

   absence, 
  so 
  far 
  as 
  yet 
  known, 
  of 
  marine 
  drifts 
  or 
  raised 
  sea-beaches 
  

   above 
  an 
  altitude 
  of 
  800 
  feet 
  higher 
  than 
  the 
  present 
  sea-level, 
  in 
  

   Scotland, 
  continental 
  Europe, 
  Asia, 
  or 
  North 
  America 
  +, 
  ought 
  to 
  be 
  

   regarded 
  as 
  investing 
  the 
  above 
  drift-zone 
  (which 
  ranges 
  between 
  

   1000 
  feet 
  and 
  1350 
  feet 
  above 
  the 
  sea) 
  with 
  an 
  additional 
  interest. 
  

  

  * 
  In 
  these 
  discoveries 
  I 
  was 
  aided 
  by 
  the 
  Committee 
  of 
  the 
  Government 
  Fund 
  

   for 
  Scientific 
  Research. 
  

  

  t 
  Quart, 
  Journ. 
  Geol. 
  Soc. 
  for 
  August 
  1881, 
  p. 
  351. 
  In 
  line 
  19 
  from 
  the 
  

   bottom 
  of 
  p. 
  352, 
  for 
  " 
  rounded 
  " 
  read 
  pounded, 
  which 
  was 
  the 
  term 
  applied 
  

   by 
  Darwin 
  to 
  the 
  condition 
  of 
  the 
  slate 
  fragments 
  on 
  Moel 
  Tryfan. 
  During 
  

   my 
  last 
  visit 
  to 
  this 
  mountain, 
  in 
  nearly 
  all 
  the 
  sections 
  then 
  exposed, 
  I 
  saw 
  

   a 
  layer 
  of 
  slate-chips 
  several 
  feet 
  in 
  tbickness, 
  which 
  rested 
  on 
  the 
  edges 
  of 
  

   the 
  nearly 
  vertical 
  slates 
  in 
  situ. 
  The 
  chips, 
  where 
  they 
  could 
  be 
  seen 
  in 
  

   profile, 
  inclined 
  (in 
  many 
  places 
  along 
  more 
  or 
  less 
  curved 
  lines) 
  from 
  the 
  JST.W. 
  

   or 
  N.N.W. 
  During 
  this 
  visit 
  one 
  section 
  showed 
  numerous 
  boulders 
  in 
  the 
  

   clay 
  (above 
  the 
  sand 
  and 
  gravel), 
  some 
  of 
  the 
  largest 
  being 
  on 
  the 
  surface, 
  or 
  

   only 
  slightly 
  imbedded. 
  

  

  \ 
  According 
  to 
  Lyell, 
  in 
  his 
  ' 
  Antiquity 
  of 
  Man,' 
  700 
  feet 
  is 
  the 
  greatest 
  

   height 
  reached 
  by 
  sbelly 
  drift 
  in 
  North 
  America. 
  

  

  