﻿THE 
  IAKE-DISTRICI 
  AND 
  NORTH 
  WALES. 
  179 
  

  

  down 
  projecting 
  rocks, 
  though, 
  under 
  exceptionally 
  favourable 
  cir- 
  

   cumstances, 
  they 
  might 
  have 
  left 
  rocks 
  more 
  or 
  less 
  rounded. 
  

   These 
  roclies 
  moutonnees 
  are 
  not 
  in 
  a 
  valley, 
  but 
  on 
  an 
  irregular 
  

   plateau. 
  They 
  occur 
  at 
  various 
  heights, 
  and 
  must 
  have 
  been 
  

   smoothed 
  by 
  ice 
  which 
  moved 
  independently 
  of 
  the 
  drainage 
  of 
  the 
  

   country. 
  Indeed 
  the 
  ice 
  by 
  which 
  many 
  of 
  them 
  were 
  smoothed 
  

   must 
  have 
  come 
  over 
  Tr 
  Arddu. 
  They 
  are 
  so 
  much 
  smoothed 
  that 
  

   it 
  is 
  often 
  difficult 
  to 
  tell 
  the 
  precise 
  direction 
  from 
  which 
  the 
  ice 
  

   came 
  ; 
  but 
  taken 
  in 
  connexion 
  with 
  a 
  number 
  of 
  strise, 
  the 
  direction 
  

   would 
  appear 
  to 
  have 
  been 
  approximately 
  N. 
  The 
  ice 
  may 
  have 
  

   radiated 
  from 
  the 
  Snowdonian 
  dome 
  south-easterly 
  towards 
  Bwlch- 
  

   cwm-orthin 
  and 
  southerly 
  towards 
  Yr 
  Arddu. 
  East 
  of 
  Moel 
  Wyn 
  

   the 
  mouth 
  of 
  Cwm 
  Orthin 
  is 
  magnificently 
  mammillated, 
  as 
  long 
  

   ago 
  mentioned 
  by 
  Professor 
  Ramsay 
  ; 
  and 
  a 
  survey 
  of 
  the 
  surface- 
  

   configuration 
  would, 
  I 
  think, 
  lead 
  to 
  the 
  conclusion 
  that 
  the 
  mam- 
  

   millation 
  was 
  principally 
  caused 
  by 
  a 
  great 
  ice-sheet 
  and 
  not 
  by 
  a 
  

   corry 
  glacier. 
  

  

  The 
  above 
  remarks 
  on 
  the 
  primary 
  glaciation 
  of 
  a 
  part 
  of 
  North 
  

   Wales 
  are 
  intended 
  as 
  supplementary 
  to 
  those 
  on 
  the 
  Lake 
  District, 
  

   and 
  not 
  as 
  exhaustive 
  of 
  the 
  subject. 
  

  

  [The 
  author 
  concludes 
  with 
  observations 
  on 
  the 
  correlation 
  of 
  

   the 
  drifts 
  of 
  the 
  Lake 
  District 
  with 
  those 
  of 
  North 
  Wales, 
  the 
  

   relation 
  between 
  lake-basins, 
  drifts, 
  and 
  moraines, 
  the 
  commence- 
  

   ment 
  of 
  the 
  great 
  submergence 
  while 
  the 
  land 
  was 
  deeply 
  covered 
  

   with 
  ice, 
  &c, 
  &c] 
  

  

  EXPLANATION 
  OF 
  PLATE 
  XX. 
  

  

  Map 
  intended 
  to 
  show 
  the 
  positions 
  and 
  directions 
  of 
  the 
  primary 
  stria? 
  

   and 
  rock-smoothing 
  in 
  connexion 
  with 
  the 
  surface-configuration 
  of 
  the 
  prin- 
  

   cipal 
  area 
  described 
  in 
  the 
  paper. 
  

  

  Discussion. 
  

  

  Mr. 
  Ward 
  was 
  inclined 
  to 
  regard 
  the 
  scratches 
  in 
  the 
  Lake-dis- 
  

   trict 
  described 
  as 
  due 
  to 
  the 
  confluence 
  of 
  several 
  glaciers, 
  so 
  as 
  to 
  

   form 
  a 
  large 
  mass 
  of 
  ice, 
  the 
  pressure 
  of 
  which 
  enabled 
  it 
  to 
  travel 
  

   over 
  the 
  ridges 
  separating 
  the 
  valleys, 
  especially 
  at 
  their 
  lower 
  ends. 
  

   If 
  the 
  phenomena 
  could 
  be 
  explained 
  in 
  this 
  manner, 
  he 
  thought 
  it 
  

   needless 
  to 
  invoke 
  the 
  existence 
  of 
  a 
  large 
  general 
  ice-sheet. 
  If 
  

   such 
  a 
  thing 
  had 
  existed, 
  it 
  must 
  have 
  brought 
  some 
  of 
  the 
  rocks 
  

   from 
  the 
  north 
  and 
  deposited 
  them 
  in 
  the 
  district 
  ; 
  and 
  this 
  was 
  not 
  

   the 
  case. 
  

  

  Mr. 
  D. 
  C. 
  Davles 
  thought 
  that 
  the 
  author 
  had 
  left 
  some 
  circum- 
  

   stances 
  out 
  of 
  view, 
  especially 
  the 
  difference 
  of 
  dates 
  of 
  the 
  strise 
  on 
  

   the 
  Welsh 
  mountains, 
  which 
  had 
  been 
  cut 
  at 
  different 
  times 
  during 
  

   the 
  elevation 
  and 
  depression 
  of 
  the 
  land. 
  He 
  instanced 
  the 
  occur- 
  

   rence 
  of 
  fragments 
  of 
  Scotch 
  granite 
  in 
  gravels 
  at 
  an 
  elevation 
  of 
  

   from 
  1500 
  to 
  2000 
  feet 
  above 
  the 
  sea. 
  

  

  