﻿192 
  D. 
  MACKINTOSH 
  ON 
  HIGH-LEVEL 
  

  

  2. 
  Ty-Cerrig 
  Area. 
  — 
  Though 
  I 
  had 
  previously 
  gone 
  over 
  this 
  area 
  

   many 
  times, 
  I 
  thought 
  it 
  desirable 
  to 
  make 
  sure 
  that 
  it 
  was 
  free 
  

   from 
  undoubted 
  marine 
  drift. 
  S.W. 
  of 
  Ty-eerrig 
  farm-house 
  (above 
  

   Berwyn 
  railway 
  station) 
  a 
  series 
  of 
  terraces 
  rise 
  one 
  above 
  another 
  

   on 
  the 
  northern 
  slope 
  of 
  a 
  hill. 
  From 
  a 
  distance 
  they 
  present 
  a 
  

   very 
  striking 
  appearance, 
  and 
  might 
  easily 
  be 
  regarded 
  as 
  raised 
  

   sea-beaches. 
  From 
  late 
  observations, 
  however, 
  I 
  have 
  been 
  led 
  to 
  

   question 
  their 
  marine 
  origin 
  ; 
  for 
  rounded 
  stones 
  are 
  comparatively 
  

   rare, 
  though 
  they 
  are 
  not 
  altogether 
  absent. 
  It 
  is 
  at 
  the 
  same 
  time 
  

   difficult 
  to 
  understand 
  how 
  the 
  chemical 
  action 
  of 
  the 
  atmosphere 
  

   on 
  Silurian 
  shale 
  or 
  grit 
  can 
  have 
  carved 
  out 
  these 
  terraces, 
  seeing 
  

   that 
  they 
  mainly 
  consist 
  of 
  loam, 
  with 
  many 
  angular 
  stones 
  ; 
  while 
  

   the 
  mechanical 
  action 
  of 
  rain-water 
  could 
  not 
  have 
  arranged 
  the 
  

   loam 
  and 
  stones 
  in 
  a 
  series 
  of 
  nearly 
  horizontal 
  shelves. 
  At 
  present 
  

   rain-torrents 
  appear 
  to 
  be 
  chiefly 
  occupied 
  in 
  making 
  transverse 
  

   breaches 
  in 
  the 
  terraces. 
  In 
  connexion 
  with 
  the 
  main 
  subject 
  of 
  

   this 
  paper 
  they 
  are 
  worthy 
  of 
  notice 
  on 
  account 
  of 
  their 
  levels 
  

   roughly 
  corresponding 
  with 
  those 
  of 
  the 
  undoubted 
  sea- 
  margins 
  

   already 
  described 
  ; 
  in 
  other 
  words, 
  they 
  range 
  from 
  about 
  1100 
  to 
  

   1300 
  feet 
  above 
  the 
  present 
  sea-level. 
  

  

  3. 
  Moelfre-uchaf 
  and 
  Frithog 
  Area. 
  — 
  North 
  of 
  Frondeg 
  (south 
  of 
  

   Minera), 
  and 
  along 
  the 
  outer 
  slopes 
  of 
  the 
  Welsh 
  mountains 
  as 
  far 
  as 
  

   the 
  Yale 
  of 
  Clwyd, 
  I 
  have 
  seen 
  no 
  marine 
  drift 
  above 
  the 
  1000 
  feet 
  

   contour-line. 
  There 
  would 
  appear 
  to 
  be 
  a 
  similar 
  absence 
  of 
  high- 
  

   level 
  marine 
  drift 
  along 
  the 
  outer 
  slopes 
  of 
  the 
  mountains 
  between 
  

   the 
  Yales 
  of 
  Clwyd 
  and 
  Conway, 
  as 
  well 
  as 
  on 
  the 
  sides 
  of 
  the 
  Yale 
  

   of 
  Conway. 
  South 
  of 
  Llandulas 
  Moelfre-uchaf 
  rises 
  to 
  1300 
  feet 
  ; 
  but 
  

   on 
  its 
  northern 
  slopes 
  and 
  flats, 
  as 
  well 
  as 
  on 
  those 
  of 
  the 
  moun- 
  

   tain 
  east 
  of 
  it, 
  and 
  in 
  the 
  pass 
  between 
  the 
  two 
  mountains, 
  I 
  could 
  

   not 
  find 
  any 
  approach 
  to 
  rounded 
  gravel, 
  though 
  there 
  were 
  nume- 
  

   rous 
  fragments 
  of 
  Wenlock 
  grit 
  and 
  shale, 
  which 
  might 
  have 
  been 
  

   readily 
  rounded 
  by 
  sea-waves. 
  It 
  is 
  likewise 
  worthy 
  of 
  remark 
  

   that 
  at 
  the 
  lower 
  levels 
  between 
  Moelfre-uchaf 
  and 
  the 
  sea- 
  coast 
  I 
  

   could 
  see 
  or 
  hear 
  of 
  no 
  very 
  decided 
  instances 
  of 
  well-rounded 
  gravel 
  

   and 
  stratified 
  sand, 
  excepting 
  on 
  the 
  ridge 
  south 
  of 
  Llandulas 
  railway- 
  

   station, 
  where 
  Mr. 
  John 
  Price 
  of 
  Chester 
  a 
  short 
  time 
  ago 
  discovered 
  

   an 
  extensive 
  deposit, 
  with 
  sea-shells, 
  at 
  a 
  height 
  of 
  probably 
  about 
  

   500 
  feet 
  above 
  the 
  sea-level. 
  This 
  deposit 
  I 
  did 
  not 
  see, 
  as 
  I 
  was 
  bent 
  

   on 
  discovering 
  high-level 
  marine 
  drifts. 
  On 
  the 
  plateau 
  east 
  of 
  

   Llanrwst, 
  called 
  Frithog 
  on 
  the 
  1-inch 
  Ordnance 
  maps, 
  at 
  heights 
  

   of 
  between 
  1000 
  feet 
  and 
  1300 
  feet, 
  I 
  could 
  find 
  very 
  few 
  rounded 
  

   stones, 
  though 
  in 
  many 
  places 
  there 
  were 
  large 
  expanses 
  of 
  angular 
  

   debris 
  underlying 
  or 
  horizontally 
  alternating 
  with 
  Boulder-clay. 
  On 
  

   the 
  opposite 
  or 
  Snowdon 
  side 
  of 
  the 
  Yale 
  of 
  Conway 
  I 
  have 
  seen 
  

   no 
  decided 
  instance 
  of 
  high-level 
  marine 
  drift, 
  though 
  in 
  the 
  neigh- 
  

   bourhood 
  of 
  Llyn-dulyn 
  many 
  blunted 
  or 
  partly 
  rounded 
  stones 
  

   may 
  be 
  seen 
  in 
  moraine 
  heaps. 
  

  

  between 
  the 
  valleys 
  of 
  the 
  Ceiriog 
  and 
  the 
  Dee, 
  while 
  in 
  the 
  latter 
  valley 
  they 
  

   are 
  numerous, 
  and 
  in 
  the 
  former 
  sparingly 
  distributed. 
  

  

  