﻿212 
  PROFESSOR 
  FORBES 
  ON 
  THE 
  GEOLOGY 
  

  

  ous, 
  which 
  appear 
  to 
  be 
  derived 
  more 
  immediately 
  from 
  boulders 
  of 
  that 
  rock 
  

   imbedded 
  in 
  the 
  drift 
  formation. 
  It 
  is 
  also 
  evident 
  that 
  the 
  partial 
  or 
  complete 
  

   removal 
  of 
  the 
  barrier 
  of 
  altered 
  rock 
  just 
  mentioned 
  has 
  changed 
  the 
  course 
  of 
  

   the 
  Tweed, 
  which 
  appears 
  once 
  to 
  have 
  swept 
  over 
  the 
  site 
  of 
  the 
  present 
  village 
  

   and 
  abbey 
  of 
  Melrose, 
  forming 
  the 
  well-marked 
  cliffs 
  at 
  Newstead, 
  which 
  may 
  

   also 
  have 
  been 
  the 
  boundary 
  of 
  a 
  fresh- 
  water 
  lake, 
  whose 
  depth 
  depended 
  on 
  the 
  

   height 
  of 
  the 
  rocky 
  barrier. 
  The 
  remarkable 
  promontory 
  of 
  Old 
  Melrose, 
  nearly 
  

   three 
  miles 
  below 
  the 
  present 
  village, 
  and 
  the 
  picturesque 
  site 
  of 
  the 
  original 
  

   abbey 
  of 
  that 
  name, 
  founded, 
  as 
  is 
  stated, 
  in 
  the 
  end 
  of 
  the 
  sixth 
  century, 
  is 
  

   unquestionably 
  owing 
  to 
  the 
  prolongation 
  of 
  the 
  trap-formation 
  of 
  the 
  Eildons, 
  

   which 
  here 
  becomes 
  very 
  narrow, 
  crossing 
  the 
  Tweed 
  just 
  below 
  Gladswood, 
  and 
  

   probably 
  uniting 
  itself 
  to 
  the 
  trap 
  of 
  Bemerside 
  Hill. 
  The 
  grey 
  wacke 
  strata 
  may 
  

   easily 
  be 
  traced 
  on 
  each 
  side 
  of 
  the 
  narrow 
  belt 
  of 
  trap 
  on 
  which 
  the 
  mansion- 
  

   house 
  of 
  Old 
  Melrose 
  stands. 
  

  

  If 
  we 
  now 
  return 
  to 
  the 
  little 
  basin 
  of 
  the 
  village 
  of 
  Melrose, 
  close 
  under 
  the 
  

   north 
  foot 
  of 
  the 
  Eildon 
  Hills, 
  we 
  find 
  the 
  following 
  arrangement 
  of 
  the 
  rocks, 
  

   the 
  understanding 
  of 
  which 
  will 
  be 
  facilitated 
  by 
  the 
  inspection 
  of 
  the 
  map, 
  

   Plate 
  VIII., 
  fig. 
  3, 
  where 
  the 
  outlines 
  of 
  the 
  formations 
  are 
  marked, 
  and 
  reference 
  

   is 
  made 
  by 
  numbers 
  to 
  the 
  principal 
  specimens, 
  and 
  by 
  lines 
  to 
  the 
  strike 
  of 
  the 
  

   strata, 
  where 
  it 
  has 
  been 
  observed. 
  

  

  In 
  the 
  course 
  of 
  a 
  little 
  stream 
  passing 
  through 
  the 
  town 
  of 
  Melrose, 
  called 
  

   Matty's 
  or 
  Dingleton 
  Burn, 
  the 
  grey 
  wacke 
  strata 
  may 
  with 
  care 
  be 
  observed 
  

   almost 
  continuously 
  ; 
  and 
  it 
  is 
  remarkable 
  that 
  they 
  exhibit 
  the 
  east 
  and 
  west 
  

   strike* 
  and 
  vertical 
  dip 
  with 
  scarcely 
  any 
  alteration 
  until 
  we 
  approach 
  the 
  

   farm-house 
  of 
  Dingleton 
  Mains, 
  when 
  they 
  become 
  suddenly 
  much 
  confused 
  

   at 
  the 
  point 
  marked 
  3. 
  In 
  the 
  field 
  above 
  Dingleton 
  farm 
  occurs 
  a 
  quarry 
  of 
  

   felspar 
  porphyry, 
  including 
  much 
  quartz 
  (specimen 
  M. 
  4 
  a.f 
  ). 
  This 
  seems 
  to 
  be 
  

   an 
  offset 
  from 
  the 
  trap 
  of 
  the 
  north-east 
  Eildon 
  Hill, 
  the 
  greywacke 
  appearing 
  

   higher 
  up 
  (at 
  5 
  and 
  6) 
  nearly 
  unaltered, 
  and 
  may 
  be 
  traced 
  almost 
  to 
  the 
  head 
  

   of 
  the 
  small 
  streams 
  which 
  rise 
  between 
  the 
  Eildons, 
  and 
  afterwards 
  join 
  the 
  

   Dingleton 
  Burn. 
  It 
  has 
  probably 
  not 
  been 
  suspected 
  that 
  so 
  large 
  a 
  portion 
  of 
  

   this 
  face 
  of 
  the 
  Eildons 
  is 
  formed 
  of 
  the 
  rock 
  of 
  the 
  surrounding 
  country. 
  The 
  

   greywacke 
  skirts 
  the 
  base 
  of 
  the 
  principal 
  Eildon 
  Hill, 
  the 
  portion 
  with 
  the 
  por- 
  

   phyry 
  passing 
  a 
  little 
  to 
  the 
  south 
  of 
  a 
  water-tank 
  on 
  the 
  moor, 
  near 
  the 
  point 
  

   marked 
  17 
  on 
  the 
  map, 
  where 
  the 
  position 
  of 
  the 
  strata 
  is 
  east 
  by 
  north, 
  and 
  

   vertical. 
  From 
  this 
  point 
  the 
  junction 
  trends 
  round 
  the 
  north 
  slope 
  of 
  Bowden 
  

   Muir, 
  until 
  we 
  reach 
  Cauldshiels 
  Loch, 
  on 
  the 
  Abbotsford 
  property, 
  where 
  the 
  

   junction 
  is 
  well 
  marked 
  on 
  the 
  eastern 
  bank. 
  

  

  * 
  The 
  deviation 
  from 
  true 
  east 
  and 
  west 
  is 
  less 
  than 
  5°. 
  

  

  f 
  The 
  collection 
  of 
  specimens 
  referred 
  to 
  in 
  this 
  paper 
  has 
  heen 
  placed 
  in 
  the 
  Museum 
  of 
  the 
  

   Royal 
  Society 
  of 
  Edinburgh. 
  

  

  