﻿186 
  D. 
  MACKINTOSH 
  ON 
  HIGH-LEVEL 
  

  

  Pen-y-graig 
  (S. 
  of 
  Minera) 
  to 
  a 
  point 
  about 
  half 
  a 
  mile 
  W.S.W. 
  of 
  

   Cefn-y-Fedw 
  farm-house, 
  its 
  extreme 
  length 
  along 
  a 
  line 
  from 
  

   N.N.E. 
  to 
  S.S.W. 
  being 
  little 
  short 
  of 
  five 
  miles 
  (see 
  Map, 
  fig. 
  1). 
  

   Its 
  average 
  breadth 
  is 
  probably 
  about 
  one 
  third 
  of 
  a 
  mile, 
  but 
  in 
  

   some 
  places 
  it 
  reaches 
  three 
  quarters 
  of 
  a 
  mile. 
  It 
  extends 
  in 
  a 
  

   direction 
  nearly 
  coincident 
  with 
  that 
  of 
  the 
  axial 
  ridge 
  on 
  the 
  eastern 
  

   slope 
  of 
  which 
  it 
  is 
  situated. 
  The 
  extreme 
  height 
  of 
  this 
  ridge 
  

   towards 
  the 
  X. 
  end 
  is 
  1495 
  feet, 
  and 
  towards 
  its 
  S. 
  end 
  1677 
  feet 
  

   (according 
  to 
  the 
  6-inch 
  Ordnance 
  map). 
  

  

  III. 
  Detailed 
  Description 
  oe 
  the 
  Drift-zone. 
  

  

  Previously 
  to 
  making 
  a 
  more 
  minute 
  survey 
  of 
  this 
  area 
  than 
  on 
  

   former 
  occasions, 
  I 
  went 
  over 
  the 
  Bryngwyn 
  district 
  immediately 
  

   north 
  of 
  Minera 
  ; 
  but 
  nowhere 
  there, 
  or 
  west 
  of 
  Minera, 
  could 
  I 
  see 
  

   any 
  stones 
  that 
  were 
  not 
  angular 
  (away 
  from 
  the 
  small 
  river 
  which 
  

   flows 
  past 
  Minera) 
  ; 
  and 
  it 
  is 
  a 
  remarkable 
  fact 
  that 
  granite 
  erratics 
  

   were 
  likewise 
  absent, 
  though 
  this 
  may 
  perhaps 
  be 
  explained 
  by 
  sup- 
  

   posing 
  that 
  the 
  district 
  was 
  too 
  deeply 
  submerged 
  to 
  intercept 
  the 
  

   floating 
  ice 
  which, 
  further 
  south 
  on 
  Minera 
  mountain, 
  left 
  numerous 
  

   granite 
  erratics. 
  On 
  walking 
  from 
  the 
  lower 
  Park 
  lead-mines 
  S.W. 
  

   towards 
  the 
  stream 
  called 
  Sy 
  chant, 
  and 
  thence 
  in 
  an 
  easterly 
  direc- 
  

   tion, 
  an 
  enormous 
  rain-rut 
  revealed 
  at 
  least 
  forty 
  feet 
  thickness 
  

   of 
  angular 
  gravel, 
  with 
  a 
  small 
  percentage 
  of 
  rounded 
  stones, 
  

   which 
  may 
  either 
  have 
  been 
  accumulated 
  by 
  terrestrial 
  agency, 
  or 
  

   speedily 
  washed 
  down 
  the 
  slope 
  by 
  the 
  sea 
  to 
  a 
  level 
  below 
  the 
  

   rounding 
  action 
  of 
  waves, 
  at 
  the 
  time 
  when 
  the 
  sea 
  was 
  depositing 
  

   the 
  gravel 
  and 
  sand 
  on 
  the 
  E. 
  side 
  of 
  Minera 
  mountain. 
  Near 
  the 
  

   summit 
  of 
  the 
  mountain 
  the 
  stones 
  were 
  nearly 
  all 
  angular, 
  and 
  

   continued 
  so 
  until 
  a 
  gentle 
  descent 
  on 
  the 
  E. 
  side 
  of 
  the 
  axial 
  

   ridge 
  (towards 
  and 
  beyond 
  the 
  upper 
  Park 
  lead-mines) 
  showed 
  a 
  

   considerable 
  proportion 
  of 
  rounded 
  stones 
  in 
  clay. 
  On 
  the 
  E. 
  side 
  

   of 
  the 
  flat 
  swampy 
  area 
  a 
  number 
  of 
  small 
  excavations 
  in 
  one 
  of 
  a 
  

   series 
  of 
  large 
  mounds, 
  1300 
  feet 
  above 
  the 
  sea 
  (W. 
  of 
  Higher 
  Wil- 
  

   ford), 
  showed 
  decided 
  indications 
  of 
  much 
  rounded 
  gravel 
  and 
  sand. 
  

   E. 
  of 
  this 
  mound, 
  at 
  about 
  1200 
  feet, 
  other 
  excavations 
  showed 
  

   similar 
  phenomena. 
  W. 
  of 
  Cae-newydd 
  (Cae-mynydd 
  on 
  one-inch 
  

   map) 
  a 
  mound, 
  about 
  1200 
  feet, 
  revealed 
  striking 
  indications 
  of 
  its 
  

   consisting 
  of 
  rounded 
  gravel 
  and 
  sand 
  ; 
  and 
  W. 
  of 
  it, 
  in 
  the 
  sides 
  

   of 
  a 
  brook-channel, 
  fine 
  gravel 
  might 
  be 
  seen 
  under 
  clay. 
  Further 
  

   S., 
  in 
  the 
  Prondeg 
  district, 
  and 
  above 
  Braich, 
  is 
  the 
  shelly 
  gravel-pit 
  

   described 
  in 
  my 
  last 
  paper 
  *, 
  and 
  the 
  gravel-mound 
  higher 
  up. 
  S.W. 
  

   of 
  the 
  latter 
  there 
  is 
  a 
  large 
  flattish 
  gravel 
  eminence, 
  and 
  in 
  the 
  

   neighbourhood 
  the 
  flat 
  ground 
  largely 
  consists 
  of 
  rounded 
  stones 
  up 
  

   to 
  1350 
  feet. 
  N. 
  of 
  a 
  stream 
  which 
  passes 
  by 
  Erwy 
  cottage, 
  and 
  

   about 
  half 
  a 
  mile 
  N.N.W. 
  of 
  that 
  cottage, 
  there 
  is 
  a 
  large 
  gravel 
  mound 
  

  

  * 
  For 
  fear 
  of 
  being 
  accused 
  of 
  exaggerating 
  heights, 
  with 
  the 
  view 
  of 
  

   supporting 
  theories, 
  I 
  underestimated 
  the 
  altitude 
  of 
  this 
  gravel-pit, 
  which 
  

   (from 
  a 
  comparison 
  of 
  neighbouring 
  bench-marks) 
  must 
  be 
  at 
  least 
  1150 
  feet 
  

   above 
  the 
  sea. 
  There 
  are 
  several 
  small 
  gravel 
  hillocks 
  at 
  a 
  short 
  distance 
  

   from 
  it. 
  

  

  