﻿460 
  PROCEEDINGS 
  OF 
  THE 
  GEOLOGICAL 
  80CIETY. 
  [June 
  22, 
  

  

  and 
  on 
  the 
  north 
  side 
  lateral 
  moraines 
  ; 
  while, 
  in 
  Gameshope 
  Valley, 
  

   at 
  the 
  mouth 
  of 
  the 
  Cleuch 
  there 
  is 
  a 
  high 
  pile 
  of 
  moraine-matter. 
  

   In 
  the 
  main 
  valley 
  the 
  detritus 
  now 
  reaches 
  on 
  the 
  east 
  to 
  250 
  feet 
  

   above 
  the 
  stream, 
  partly 
  from 
  the 
  additional 
  transported 
  matter 
  

   of 
  Donald's 
  Cleuch, 
  partly 
  because 
  a 
  ridge 
  of 
  grit 
  crosses 
  the 
  valley 
  

   alongside 
  of 
  the 
  tributary 
  burn. 
  From 
  this 
  point 
  downwards 
  the 
  

   Boulder-clay 
  has 
  been 
  completely 
  worn 
  out 
  of 
  the 
  valley 
  by 
  the 
  ice- 
  

   flow, 
  and 
  is 
  now 
  confined 
  to 
  patches, 
  among 
  the 
  crags, 
  500 
  feet 
  

   above 
  the 
  stream. 
  The 
  moraine-detritus 
  no 
  longer 
  forms 
  a 
  con- 
  

   tinuous 
  covering, 
  but 
  is 
  scattered 
  in 
  nooks 
  of 
  rocks, 
  gathered 
  in 
  

   mounds 
  among 
  the 
  roches 
  moutonnees 
  which 
  stud 
  the 
  sides 
  and 
  

   floor 
  of 
  the 
  valley, 
  or 
  perched 
  on 
  bare 
  tables 
  of 
  grit 
  too 
  decomposing 
  

   to 
  retain 
  striations. 
  Patches 
  of 
  alluvium 
  and 
  peat 
  lie 
  surrounded 
  

   by 
  smoothed 
  bosses 
  of 
  rock, 
  or 
  retained 
  by 
  heaps 
  of 
  rubbish 
  ; 
  piles 
  

   of 
  large 
  blocks 
  alternate 
  with 
  mounds 
  of 
  the 
  finer 
  and 
  more 
  cha- 
  

   racteristic 
  moraine-matter 
  ; 
  bosses 
  rise 
  to 
  a 
  height 
  of 
  40 
  feet 
  in 
  the 
  

   centre 
  of 
  the 
  glen, 
  under 
  whose 
  lee 
  lie 
  long 
  ridges 
  of 
  debris. 
  In 
  

   short, 
  the 
  valley 
  presents 
  every 
  variety 
  of 
  ice-action 
  ; 
  it 
  is 
  as 
  it 
  were 
  

   the 
  dissection 
  of 
  a 
  glacier. 
  This 
  glen, 
  interesting 
  geologically 
  and 
  

   remarkable 
  as 
  a 
  scene 
  of 
  savage 
  gloom 
  and 
  desolation 
  in 
  strong 
  

   contrast 
  with 
  the 
  soft 
  pastoral 
  beauty 
  of 
  the 
  surrounding 
  country, 
  

   ends 
  at 
  the 
  head 
  of 
  the 
  lower 
  Talla 
  Valley. 
  The 
  alluvium 
  of 
  the 
  

   latter 
  comes 
  a 
  little 
  way 
  up 
  stream, 
  and 
  skirts 
  the 
  base 
  of 
  a 
  lateral 
  

   moraine 
  prominent 
  upon 
  the 
  detritus 
  clothing 
  the 
  flanks 
  of 
  Caiiavin 
  

   and 
  continuous 
  with 
  that 
  descending 
  over 
  the 
  Linnhead. 
  

  

  The 
  absence 
  of 
  striations 
  in 
  these 
  valleys 
  allows 
  no 
  other 
  guide 
  

   in 
  estimating 
  the 
  depth 
  of 
  the 
  ice-stream 
  than 
  the 
  height 
  of 
  the 
  

   detritus 
  above 
  the 
  bottom 
  of 
  the 
  valley. 
  The 
  uncertainty 
  of 
  

   inference 
  drawn 
  from 
  this 
  alone 
  is 
  well 
  illustrated 
  at 
  Loch 
  Skene, 
  

   where 
  moraine 
  -matter 
  is 
  found 
  on 
  Loch 
  Craig 
  about 
  100 
  feet 
  higher 
  

   than 
  the 
  termino-lateral 
  moraine 
  opposite. 
  This 
  may 
  be 
  accounted 
  

   for, 
  on 
  the 
  one 
  hand, 
  by 
  the 
  close 
  proximity 
  of 
  a 
  cliff 
  along 
  whose 
  

   base 
  rubbish 
  would 
  be 
  piled 
  up 
  in 
  large 
  quantities, 
  on 
  the 
  other, 
  by 
  

   the 
  spreading 
  of 
  a 
  glacier 
  in 
  crossing 
  the 
  open 
  ground, 
  and 
  the 
  wider 
  

   distribution 
  over 
  its 
  surface, 
  and 
  diversion 
  into 
  either 
  of 
  its 
  branches, 
  

   of 
  the 
  rubbish 
  derived 
  from 
  the 
  loch-head. 
  Keeping 
  in 
  view 
  the 
  

   possible 
  recurrence 
  of 
  similar 
  circumstances 
  in 
  the 
  curves 
  and 
  ex- 
  

   pansions 
  of 
  the 
  valleys, 
  it 
  must 
  also 
  be 
  remembered 
  that 
  much 
  of 
  

   the 
  detritus 
  on 
  the 
  hill-sides 
  may 
  have 
  been 
  washed 
  down 
  into 
  the 
  

   hollows, 
  and, 
  in 
  places, 
  has 
  even 
  been 
  wholly 
  removed. 
  The 
  average 
  

   height, 
  however, 
  to 
  which 
  moraine-matter 
  extends 
  in 
  those 
  glens, 
  

   whose 
  similarity 
  in 
  shape 
  and 
  dimensions 
  renders 
  this 
  comparison 
  

   possible, 
  is 
  200 
  feet 
  towards 
  the 
  lower 
  part 
  of 
  their 
  course. 
  In 
  

   Upper 
  Talla, 
  below 
  the 
  craigs,the 
  horizontal 
  distance 
  at 
  that 
  level, 
  from 
  

   side 
  to 
  side, 
  is 
  over 
  1000 
  feet. 
  In 
  Gameshope, 
  above 
  the 
  Shepherd's 
  

   House, 
  it 
  approaches 
  1500 
  feet, 
  but 
  a 
  little 
  lower 
  contracts 
  to 
  1000 
  

   feet. 
  At 
  Megget 
  Head 
  the 
  elevation 
  is 
  about 
  100 
  feet, 
  with 
  a 
  

   horizontal 
  distance 
  of 
  about 
  1100 
  feet. 
  At 
  a 
  corresponding 
  point 
  

   above 
  Talla 
  Linnfoots 
  the 
  measurements 
  give 
  nearly 
  the 
  same 
  

   result. 
  If 
  the 
  striae 
  alluded 
  to 
  at 
  Firthy 
  Brig 
  Head 
  belong 
  to 
  the 
  

  

  