﻿176 
  T. 
  F. 
  JAMIESON 
  ON 
  THE 
  RED 
  CLAY 
  

  

  derived 
  from 
  the 
  gradual 
  waste 
  of 
  the 
  bank. 
  Few 
  of 
  the 
  stones 
  

   show 
  glacial 
  scratches, 
  which 
  may 
  be 
  owing 
  to 
  their 
  hard 
  crys- 
  

   talline 
  quality 
  in 
  a 
  great 
  measure. 
  This 
  Boulder-clay 
  consists 
  of 
  a 
  

   fine 
  impalpable 
  mud, 
  mixed 
  with 
  small 
  gritty 
  particles 
  of 
  quartz 
  

   and 
  felspar, 
  and 
  stones 
  of 
  all 
  shapes 
  and 
  sizes, 
  stuck 
  in 
  all 
  manner 
  

   of 
  positions, 
  the 
  whole 
  forming 
  a 
  dense 
  impenetrable 
  mass 
  like 
  

   concrete. 
  The 
  fineness 
  of 
  the 
  mud, 
  which 
  is 
  as 
  fine 
  as 
  flour, 
  makes 
  

   it 
  adhere 
  tenaciously 
  to 
  the 
  stones 
  like 
  plaster. 
  The 
  included 
  stones 
  

   are 
  such 
  as 
  might 
  be 
  got 
  from 
  the 
  rocks 
  along 
  the 
  valley 
  of 
  the 
  Dee, 
  

   of 
  which 
  the 
  Bay 
  of 
  Nigg 
  forms 
  the 
  natural 
  termination 
  ; 
  and 
  this 
  

   grey 
  Boulder-clay 
  is, 
  no 
  doubt, 
  the 
  mud 
  accumulated 
  beneath 
  the 
  

   glacier 
  which 
  descended 
  that 
  valley. 
  

  

  4. 
  At 
  the 
  top 
  of 
  this 
  grey 
  mud 
  there 
  is, 
  in 
  some 
  parts 
  of 
  the 
  

   section, 
  a 
  variable 
  amount 
  of 
  reddish 
  Boulder-clay 
  (no. 
  4), 
  which 
  

   contains 
  round 
  pebbles 
  of 
  brownish 
  quartz 
  with 
  a 
  reddish 
  exterior, 
  

   such 
  as 
  occur 
  in 
  the 
  Old 
  Red 
  Sandstone 
  conglomerate, 
  and 
  bits 
  of 
  

   volcanic 
  rock 
  and 
  jasper, 
  like 
  what 
  are 
  found 
  in 
  the 
  red 
  clay 
  of 
  the 
  

   Aberdeenshire 
  coast 
  further 
  north. 
  This 
  reddish 
  portion 
  is 
  seen 
  at 
  

   the 
  middle 
  of 
  the 
  section 
  and 
  towards 
  the 
  north 
  end 
  ; 
  and 
  the 
  water 
  

   trickling 
  down 
  from 
  it 
  imparts 
  a 
  red 
  tinge 
  to 
  the 
  surface 
  of 
  the 
  grey 
  

   clay 
  beneath. 
  So 
  far 
  as 
  my 
  observation 
  goes, 
  none 
  of 
  these 
  Old 
  Red 
  

   Sandstone 
  pebbles 
  nor 
  fragments 
  of 
  the 
  same 
  volcanic 
  rocks 
  occur 
  

   in 
  the 
  deep 
  mass 
  of 
  grey 
  clay 
  ; 
  they 
  seem 
  confined 
  to 
  this 
  red 
  portion 
  

   at 
  the 
  top, 
  which 
  evidently 
  represents 
  the 
  red 
  Boulder-clay 
  of 
  the 
  

   quarry 
  section 
  at 
  the 
  Cove 
  (fig. 
  2). 
  Bed 
  Boulder-clay 
  containing 
  

   the 
  same 
  mineral 
  debris 
  and 
  bits 
  of 
  sandstone 
  is 
  seen 
  covering 
  the 
  

   surface 
  of 
  the 
  rock 
  at 
  the 
  first 
  railway- 
  cutting 
  to 
  the 
  south 
  of 
  the 
  

   Bay 
  of 
  Nigg, 
  close 
  beside 
  the 
  mud 
  cliff 
  I 
  am 
  describing, 
  the 
  grey 
  

   clay 
  being 
  absent. 
  This 
  red 
  portion, 
  no. 
  4, 
  with 
  its 
  distinct 
  colour 
  

   and 
  peculiar 
  mineral 
  contents, 
  clearly 
  betokens 
  a 
  change 
  of 
  conditions, 
  

   with 
  transport 
  of 
  material 
  from 
  a 
  different 
  quarter 
  from 
  that 
  of 
  the 
  

   grey 
  clay. 
  

  

  5. 
  At 
  the 
  north 
  end 
  of 
  the 
  section 
  there 
  is 
  a 
  denuded 
  patch 
  of 
  

   fine 
  brownish 
  sandy 
  silt, 
  free 
  from 
  stones 
  and 
  containing 
  apparently 
  

   some 
  seams 
  of 
  reddish 
  silty 
  clay 
  ; 
  but 
  I 
  could 
  see 
  no 
  pure 
  mass 
  of 
  

   red 
  clay 
  in 
  it, 
  and 
  the 
  whole 
  is 
  so 
  soft 
  and 
  sandy 
  that 
  the 
  swallows 
  

   have 
  pierced 
  it 
  with 
  many 
  of 
  their 
  nesting-holes. 
  It 
  has 
  been 
  cut 
  

   down 
  in 
  a 
  very 
  irregular 
  manner 
  by 
  the 
  overlying 
  gravel, 
  which 
  

   envelops 
  it 
  quite 
  unconformably 
  ; 
  and 
  its 
  stratification 
  is 
  in 
  some 
  

   places 
  bent 
  and 
  twisted. 
  Its 
  structure 
  indicates 
  deposition 
  from 
  

   water 
  ; 
  and 
  as 
  it 
  differs 
  much 
  from 
  the 
  stuff 
  both 
  above 
  and 
  beneath, 
  

   it 
  must 
  have 
  been 
  formed 
  under 
  very 
  different 
  conditions. 
  It 
  may 
  

   be 
  a 
  remnant 
  of 
  marine 
  silt 
  deposited 
  during 
  the 
  period 
  of 
  submer- 
  

   gence, 
  when 
  the 
  beds 
  of 
  fine 
  clay 
  were 
  laid 
  down 
  along 
  the 
  coast. 
  

  

  6. 
  The 
  upper 
  gravel 
  is 
  a 
  very 
  coarse 
  jumble 
  of 
  stones,'pebbles, 
  and 
  

   sand, 
  without 
  any 
  regular 
  arrangement. 
  The 
  materials 
  of 
  which 
  

   it 
  consists 
  range 
  in 
  size 
  from 
  sand 
  and 
  pebbles 
  up 
  to 
  blocks 
  

   and 
  boulders 
  3 
  or 
  4 
  feet 
  in 
  diameter. 
  There 
  are 
  masses 
  of 
  

   shattered 
  rock 
  debris, 
  such 
  as 
  might 
  be 
  found 
  at 
  the 
  base 
  of 
  a 
  

   weathered 
  cliff 
  of 
  gneiss 
  ; 
  and 
  there 
  are 
  here 
  and 
  there 
  patches 
  of 
  

  

  