﻿188 
  I). 
  MACKINTOSH 
  ON 
  HIGH-LEVEL 
  

  

  sea, 
  mentioned 
  in 
  my 
  last 
  paper. 
  Through 
  a 
  fear 
  of 
  exaggerating 
  

   heights, 
  I 
  mistook 
  the 
  height 
  of 
  this 
  pit 
  for 
  that 
  of 
  the 
  one 
  higher 
  

   np, 
  until 
  I 
  paced 
  the 
  ground, 
  the 
  result 
  of 
  my 
  last 
  visit 
  being 
  that 
  

   the 
  upper 
  pit 
  (in 
  which 
  I 
  found 
  shell-fragments) 
  is 
  at 
  least 
  1280 
  feet 
  

   above 
  the 
  sea. 
  Some 
  distance 
  S. 
  of 
  Mountain 
  Lodge 
  there 
  is 
  a 
  gravel- 
  

   pit 
  showing 
  very 
  fine 
  sand 
  and 
  rounded 
  stones 
  at 
  the 
  end 
  of 
  a 
  ridge 
  

   which 
  extends 
  a 
  great 
  distance 
  in 
  a 
  westerly 
  direction. 
  S.E. 
  of 
  Moun- 
  

   tain 
  Lodge 
  (as 
  well 
  shown 
  on 
  the 
  1-inch 
  Ordnance 
  map) 
  there 
  is 
  a 
  

   ridge 
  about 
  one 
  third 
  of 
  a 
  mile 
  in 
  length, 
  which 
  is 
  very 
  steep 
  on 
  the 
  

   western 
  side. 
  So 
  far 
  as 
  can 
  be 
  seen, 
  the 
  summit, 
  which 
  rises 
  to 
  

   1031 
  feet, 
  is 
  nearly 
  all 
  covered 
  with 
  rounded 
  gravel. 
  At 
  the 
  south 
  

   end 
  the 
  gravel 
  is 
  extra 
  rounded, 
  and 
  the 
  sand 
  finely 
  laminated, 
  

   especially 
  at 
  an 
  elevation 
  of 
  between 
  900 
  and 
  1000 
  feet. 
  The 
  

   gravel 
  extends 
  some 
  distance 
  down 
  the 
  southern 
  slope 
  of 
  the 
  hill, 
  

   having 
  probably 
  been 
  washed 
  down 
  while 
  the 
  land 
  was 
  rising. 
  

   Lower 
  down 
  the 
  stones 
  are 
  nearly 
  all 
  angular 
  ; 
  and 
  this 
  is 
  even 
  the 
  

   case 
  in 
  the 
  bed 
  of 
  Afon 
  Eitha, 
  which 
  flows 
  in 
  an 
  easterly 
  direction 
  

   along 
  the 
  southern 
  base 
  of 
  the 
  hill. 
  Here, 
  and 
  elsewhere 
  in 
  the 
  

   drift- 
  zone 
  under 
  consideration, 
  it 
  is 
  obvious 
  that 
  the 
  streams 
  have 
  

   not 
  yet 
  had 
  time 
  to 
  round 
  the 
  angular 
  stones 
  with 
  which 
  they 
  have 
  

   met 
  in 
  their 
  courses, 
  and 
  that 
  where 
  many 
  rounded 
  stones 
  are 
  

   found 
  in 
  their 
  channels 
  they 
  have 
  been 
  derived 
  from 
  the 
  surrounding 
  

   marine 
  drift. 
  S.S.W. 
  of 
  Afon 
  Eitha, 
  near 
  Ty 
  Bhywyn, 
  the 
  eastern 
  

   part 
  of 
  Bryn 
  Adda 
  Flat 
  (see 
  6-inch 
  Ordnance 
  map) 
  contains 
  many 
  

   stones 
  more 
  or 
  less 
  rounded. 
  S.W. 
  of 
  Ty 
  Hhywyn 
  a 
  number 
  of 
  

   small 
  grass-covered 
  swellings 
  of 
  the 
  ground 
  above 
  moss, 
  bog, 
  or 
  

   clay 
  show 
  indications 
  of 
  being 
  composed 
  of 
  rounded 
  gravel 
  and 
  

   sand 
  ; 
  and 
  the 
  sides 
  of 
  roads 
  and 
  brook-channels 
  show 
  a 
  con- 
  

   siderable 
  percentage 
  of 
  rounded 
  stones. 
  E. 
  of 
  Ty 
  Rhywyn 
  the 
  

   ground 
  in 
  some 
  places 
  undulates 
  in 
  a 
  similar 
  manner 
  to 
  that 
  which 
  

   further 
  N. 
  has 
  been 
  found 
  to 
  consist 
  of 
  rounded 
  gravel 
  and 
  sand. 
  

   Between 
  Bryn 
  -Adda 
  cottage 
  and 
  Hafod 
  there 
  is 
  the 
  largest 
  gravel 
  

   and 
  sand 
  mound 
  to 
  be 
  met 
  with 
  in 
  the 
  whole 
  drift-area. 
  It 
  may 
  

   be 
  seen 
  from 
  a 
  great 
  distance, 
  and 
  from 
  many 
  points 
  of 
  the 
  compass. 
  

   Its 
  height 
  above 
  the 
  sea 
  is 
  nearly 
  1100 
  feet. 
  The 
  stones 
  are 
  more 
  or 
  

   less 
  rounded, 
  and 
  the 
  gravel 
  and 
  fine 
  sand 
  stratified 
  *. 
  S.AV. 
  of 
  the 
  

   neighbourhood 
  of 
  Hafod, 
  well-rounded, 
  subangular, 
  and 
  angular 
  

   stones 
  may 
  be 
  seen 
  along 
  the 
  side 
  of 
  the 
  stone 
  wall 
  which 
  separates 
  

   the 
  arable 
  from 
  the 
  waste 
  land 
  on 
  the 
  eastern 
  side 
  of 
  the 
  mountain 
  

   called 
  Cefn-y-fedw 
  on 
  the 
  1-inch 
  Ordnance 
  map 
  ; 
  and 
  many 
  rounded 
  

   stones 
  may 
  be 
  found 
  W.S.W. 
  of 
  Cefn-y-fedw 
  farmhouse, 
  on 
  the 
  dip 
  

   slope 
  of 
  the 
  Carboniferous 
  sandstone, 
  up 
  to 
  within 
  a 
  short 
  distance 
  

   of 
  the 
  brink 
  of 
  the 
  escarpment, 
  where 
  their 
  height 
  above 
  the 
  sea 
  

   must 
  be 
  at 
  least 
  1300 
  feet. 
  It 
  is 
  worthy 
  of 
  remark 
  that 
  below 
  the 
  

   1100 
  contour-line, 
  S.E. 
  of 
  Cefn-y-fedw, 
  the 
  stones 
  down 
  to 
  a 
  

   considerably 
  lower 
  level 
  are 
  strikingly 
  angular. 
  This 
  furnishes 
  

  

  * 
  Among 
  the 
  stones, 
  local 
  Carboniferous 
  sandstone 
  or 
  grit, 
  and 
  quartz 
  

   or 
  quartzose 
  conglomerate, 
  predominate 
  ; 
  but 
  there 
  are 
  also 
  specimens 
  of 
  

   Wenlock 
  grit 
  and 
  slate 
  from 
  the 
  W. 
  or 
  S., 
  and 
  chert 
  probably 
  from 
  the 
  indi- 
  

   rectly 
  local 
  Mountain 
  Limestone. 
  

  

  