﻿ON 
  THE 
  CRAG-SHELL 
  GRAVEL 
  BEDS 
  OF 
  ABERDEENSHIRE. 
  147 
  

  

  along 
  with 
  much 
  of 
  the 
  mineral 
  debris, 
  have 
  been 
  derived 
  from 
  the 
  

   destruction 
  of 
  strata 
  of 
  older 
  date 
  that 
  existed 
  probably 
  somewhere 
  

   in 
  the 
  neighbourhood 
  before 
  the 
  glacial 
  period 
  began. 
  

  

  The 
  species 
  of 
  Mollusca 
  seem 
  to 
  indicate 
  that 
  the 
  Red 
  Crag 
  

   was 
  represented 
  (and 
  perhaps 
  even 
  the 
  Coralline), 
  together 
  with 
  

   probably 
  some 
  of 
  the 
  later 
  Bridlington 
  or 
  Chillesford 
  beds 
  ; 
  but 
  here 
  

   we 
  have 
  nothing 
  but 
  the 
  debris, 
  the 
  mere 
  wreck 
  of 
  these 
  deposits. 
  

  

  As 
  no 
  Crag 
  fossils 
  have 
  been 
  found 
  in 
  any 
  other 
  part 
  of 
  Scotland 
  

   (although 
  they 
  occur 
  in 
  Iceland), 
  their 
  existence 
  here 
  is 
  a 
  matter 
  of 
  

   some 
  interest, 
  and 
  may 
  help 
  to 
  throw 
  light 
  on 
  the 
  history 
  of 
  the 
  last 
  

   modifications 
  which 
  the 
  surface 
  of 
  the 
  country 
  has 
  undergone. 
  

  

  Extent 
  and 
  Distribution 
  of 
  the 
  Gravel. 
  (See 
  Map, 
  fig. 
  1.) 
  

  

  So 
  far 
  as 
  I 
  have 
  been 
  able 
  to 
  discover, 
  the 
  deposit 
  of 
  sand 
  and 
  

   gravel 
  containing 
  these 
  shells 
  is 
  confined 
  to 
  the 
  district 
  of 
  Slains 
  and 
  

   Cruden, 
  which 
  are 
  two 
  parishes 
  situated 
  on 
  the 
  east 
  coast 
  of 
  Aber- 
  

   deenshire, 
  to 
  the 
  north 
  of 
  the 
  river 
  Ythan, 
  between 
  the 
  seaport 
  

   towns 
  of 
  Aberdeen 
  and 
  Peterhead, 
  but 
  nearest 
  to 
  the 
  latter 
  place. 
  

   In 
  no 
  other 
  part 
  of 
  Aberdeenshire 
  or 
  of 
  Scotland 
  have 
  I 
  met 
  with 
  it. 
  

   I 
  have, 
  however, 
  got 
  a 
  large 
  and 
  nearly 
  perfect 
  valve 
  of 
  a 
  charac- 
  

   teristic 
  Crag 
  shell 
  (Astarte 
  mutabilis), 
  which 
  was 
  sent 
  me 
  from 
  a 
  

   railway- 
  cutting 
  a 
  few 
  miles 
  to 
  the 
  west 
  of 
  Peterhead, 
  where 
  it 
  

   occurred 
  in 
  a 
  bed 
  of 
  red 
  clay 
  of 
  glacial 
  age. 
  This 
  shell 
  contains 
  

   some 
  of 
  the 
  same 
  peculiar 
  concrete 
  already 
  mentioned, 
  but 
  is 
  in 
  

   a 
  better 
  state 
  of 
  preservation 
  than 
  any 
  of 
  my 
  specimens 
  from 
  

   Slains 
  and 
  Cruden. 
  

  

  The 
  part 
  of 
  Slains 
  and 
  Cruden 
  to 
  which 
  the 
  shelly 
  gravel 
  seems 
  to 
  

   be 
  confined 
  is 
  bounded 
  on 
  the 
  east 
  by 
  the 
  sea, 
  on 
  the 
  south 
  by 
  

   a 
  desolate 
  tract 
  of 
  blown 
  sand 
  called 
  Porvie, 
  on 
  the 
  west 
  by 
  a 
  

   small 
  stream 
  known 
  as 
  the 
  Burn 
  of 
  Porvie, 
  and 
  on 
  the 
  north 
  

   by 
  another 
  small 
  stream 
  called 
  the 
  Water 
  of 
  Cruden. 
  The 
  gravel, 
  

   however, 
  does 
  not 
  cover 
  the 
  whole 
  or 
  even 
  the 
  greater 
  part 
  of 
  this 
  

   district, 
  which 
  embraces 
  an 
  area 
  of 
  about 
  twelve 
  square 
  miles, 
  

   forming 
  a 
  tract 
  of 
  bare 
  undulating 
  ground, 
  all 
  under 
  cultivation 
  

   and 
  culminating 
  in 
  an 
  eminence 
  named 
  Highlaw, 
  the 
  top 
  of 
  which 
  

   is 
  300 
  feet 
  above 
  the 
  present 
  level 
  of 
  the 
  sea. 
  This 
  Highlaw 
  

   is 
  situated 
  not 
  exactly 
  in 
  the 
  centre 
  of 
  the 
  district, 
  but 
  somewhat 
  

   to 
  the 
  north 
  of 
  the 
  centre 
  ; 
  and 
  from 
  it 
  the 
  ground 
  slopes 
  away 
  

   on 
  all 
  sides 
  in 
  gentle 
  undulations, 
  most 
  of 
  it 
  lying 
  at 
  altitudes 
  

   of 
  from 
  100 
  to 
  200 
  feet. 
  The 
  coast-line 
  is 
  for 
  the 
  most 
  part 
  formed 
  

   of 
  steep 
  grassy 
  banks 
  and 
  rocky 
  cliffs, 
  generally 
  about 
  100 
  feet 
  

  

  The 
  distribution 
  of 
  the 
  gravel 
  within 
  this 
  district 
  seems 
  confined 
  

   for 
  the 
  most 
  part 
  to 
  an 
  irregular 
  belt 
  of 
  ground 
  sweeping 
  round 
  

   Highlaw 
  as 
  a 
  sort 
  of 
  centre, 
  and 
  at 
  a 
  distance 
  of 
  a 
  mile 
  or 
  two 
  from 
  

   it. 
  It 
  extends 
  furthest 
  from 
  Highlaw 
  in 
  a 
  south 
  or 
  south-west 
  

   direction, 
  near 
  to 
  the 
  fishing-village 
  of 
  Collieston, 
  which 
  lies 
  on 
  the 
  

   coast 
  about 
  3-| 
  miles 
  off; 
  and 
  along 
  its 
  whole 
  extent 
  this 
  shelly 
  

   gravel 
  seems 
  to 
  have 
  been 
  arranged 
  in 
  a 
  series 
  of 
  mounds 
  or 
  

  

  