﻿PEOE. 
  C. 
  LAPAVOETH 
  ON 
  THE 
  GIEVAN 
  SUCCESSION. 
  543 
  

  

  other 
  hand, 
  the 
  cautious 
  study 
  of 
  these 
  deposits 
  led 
  to 
  the 
  demon- 
  

   stration 
  of 
  the 
  contrary 
  opinion, 
  i. 
  e. 
  that 
  their 
  distinct 
  fossil 
  assem- 
  

   blages 
  were 
  restricted, 
  as 
  in 
  other 
  lands, 
  to 
  different 
  stratigraphical 
  

   zones, 
  British 
  geologists 
  would 
  feel 
  justified 
  in 
  attempting 
  the 
  

   correlation 
  of 
  their 
  own 
  Lower 
  Palaeozoic 
  subformations 
  with 
  their 
  

   nearest 
  representatives 
  all 
  over 
  the 
  world. 
  

  

  In 
  the 
  following 
  pages 
  I 
  shall 
  give 
  the 
  results 
  of 
  a 
  personal 
  study 
  

   of 
  these 
  Carrick 
  rocks 
  as 
  they 
  are 
  exposed 
  in 
  the 
  area 
  which 
  lies 
  

   immediately 
  to 
  the 
  east 
  and 
  south 
  of 
  the 
  sea-port 
  town 
  of 
  Girvan. 
  

   If 
  the 
  testimony 
  here 
  brought 
  forward 
  be 
  accepted, 
  we 
  are 
  not 
  only 
  

   forced 
  to 
  the 
  conclusion 
  that 
  these 
  Lower 
  Palaeozoic 
  strata 
  attain 
  

   a 
  thickness 
  and 
  a 
  geological 
  importance 
  hitherto 
  unsuspected, 
  

   while 
  in 
  the 
  definiteness 
  and 
  gradation 
  of 
  their 
  component 
  subfor- 
  

   mations 
  and 
  in 
  the 
  abundance 
  of 
  their 
  special 
  fossils 
  they 
  bear 
  

   favourable 
  comparison 
  with 
  the 
  classic 
  deposits 
  of 
  Siluria 
  itself, 
  

   but 
  we 
  are 
  also 
  compelled 
  to 
  acknowledge 
  that 
  in 
  the 
  vertical 
  

   sequence 
  of 
  these 
  subformations, 
  in 
  the 
  direction 
  and 
  amount 
  of 
  

   the 
  development 
  of 
  life 
  — 
  even 
  in 
  the 
  grouping 
  of 
  certain 
  genera 
  

   and 
  species 
  and 
  in 
  the 
  restriction 
  of 
  defined 
  assemblages 
  to 
  special 
  

   zones 
  — 
  they 
  correspond 
  to 
  a 
  most 
  remarkable 
  degree 
  with 
  the 
  

   homotaxeous 
  or 
  synchronous 
  deposits 
  hitherto 
  studied 
  in 
  detail 
  in 
  

   Southern 
  Britain, 
  Europe, 
  and 
  America. 
  

  

  2. 
  General 
  Characteristics 
  of 
  the 
  Girvan 
  Region. 
  

  

  The 
  fossiliferous 
  Lower 
  Palaeozoic 
  strata 
  which 
  will 
  be 
  noticed 
  in 
  

   the 
  present 
  memoir 
  lie 
  within 
  and 
  around 
  the 
  extensive 
  and 
  more 
  

   or 
  less 
  elevated 
  tableland 
  which 
  separates 
  the 
  lower 
  portions 
  of 
  the 
  

   river-valleys 
  of 
  the 
  Girvan 
  and 
  Stinehar. 
  Westward, 
  this 
  plateau 
  

   is 
  abruptly 
  truncated 
  by 
  the 
  waters 
  of 
  the 
  Firth 
  of 
  Clyde. 
  Its 
  

   seaward 
  margin 
  is 
  formed 
  by 
  a 
  line 
  of 
  almost 
  vertical 
  cliffs, 
  based 
  

   upon 
  a 
  coast 
  platform, 
  which 
  is 
  alternately 
  a 
  raised 
  beach 
  and 
  a 
  

   submerged 
  fringe 
  of 
  dangerous 
  reefs 
  and 
  skerries. 
  Eastward, 
  its 
  

   limits 
  are 
  defined 
  with 
  tolerable 
  distinctness 
  by 
  the 
  commencement 
  

   of 
  a 
  superimposed 
  terrace, 
  composed 
  essentially 
  of 
  more 
  recent 
  

   volcanic 
  rocks, 
  of 
  the 
  general 
  age 
  of 
  the 
  Old 
  Red 
  Sandstone. 
  The 
  

   south-western 
  portion 
  of 
  the 
  plateau 
  itself 
  forms 
  the 
  subdistrict 
  of 
  

   Ballantrae, 
  which 
  is 
  occupied 
  by 
  igneous 
  and 
  altered 
  rocks 
  of 
  undeter- 
  

   mined 
  age, 
  and 
  which 
  will 
  be 
  therefore 
  only 
  casually 
  referred 
  to 
  in 
  

   the 
  present 
  paper. 
  The 
  major 
  portion, 
  or 
  main 
  Girvan 
  plateau, 
  to 
  

   which 
  our 
  attention 
  will 
  be 
  chiefly 
  directed, 
  and 
  which 
  is 
  based 
  

   upon 
  the 
  fossiliferous 
  deposits, 
  has 
  a 
  length, 
  from 
  the 
  coast 
  near 
  

   Girvan 
  to 
  the 
  edge 
  of 
  the 
  Volcanic 
  Terrace 
  of 
  Garleflm, 
  of 
  about 
  

   12 
  miles, 
  and 
  a 
  breadth, 
  from 
  the 
  edge 
  of 
  the 
  Uplands 
  to 
  the 
  

   southern 
  slopes 
  of 
  the 
  Girvan 
  valley, 
  of 
  about 
  8 
  miles. 
  

  

  In 
  addition 
  to 
  this 
  main 
  exposure, 
  the 
  Lower 
  Palaeozoic 
  rocks 
  

   make 
  their 
  appearance 
  at 
  the 
  surface 
  within 
  the 
  Girvan 
  region 
  in 
  

   two 
  subordinate 
  and 
  supplementary 
  areas, 
  viz. 
  those 
  of 
  Craighead 
  

   and 
  Straiton. 
  The 
  Craighead, 
  or 
  Mulloch-Hill 
  area, 
  is 
  formed 
  of 
  

   the 
  wooded 
  ridges 
  lying 
  to 
  the 
  north 
  of 
  the 
  Girvan 
  valley. 
  It 
  is 
  a 
  

  

  