﻿524 
  MESSRS. 
  C. 
  I. 
  GARDINER 
  AND 
  S. 
  H. 
  REYNOLDS 
  ON 
  [Dec. 
  1 
  89 
  7, 
  

  

  could 
  obtain 
  no 
  evidence 
  of 
  this, 
  though 
  at 
  this 
  point 
  signs 
  of 
  dis- 
  

   turbance 
  begin 
  which 
  become 
  more 
  marked 
  as 
  we 
  proceed 
  southward. 
  

  

  Beyond 
  the 
  graptolitic 
  shale 
  the 
  rock 
  is 
  still 
  an 
  ashy 
  conglomerate 
  

   containing 
  numerous 
  blocks 
  of 
  coarse 
  porphyrite, 
  of 
  ashes 
  of 
  various 
  

   types, 
  and 
  of 
  fine 
  andesites, 
  and 
  then 
  as 
  the 
  roartello 
  tower 
  is 
  

   approached 
  thin 
  bands 
  of 
  limestone, 
  often 
  ashy 
  in 
  their 
  nature, 
  

   come 
  to 
  be 
  interbedded 
  with 
  the 
  ashy 
  conglomerate, 
  while 
  bands 
  of 
  

   dark-grey 
  calcareous 
  shales 
  also 
  occur, 
  and 
  have 
  yielded, 
  at 
  the 
  spot 
  

   marked 
  A 
  in 
  the 
  map 
  (PI. 
  XLIII), 
  fossils 
  which 
  have 
  been 
  identified 
  

   for 
  us 
  by 
  Mr. 
  F. 
  R. 
  Cowper 
  Reed 
  as 
  Orthis 
  simplex, 
  M'Coy 
  ?, 
  

   OrtJiis 
  sp., 
  Rafinesquina 
  eocpansa, 
  Sow., 
  Plectambonites 
  sericea, 
  Sow., 
  

   and 
  fragments 
  of 
  trilobites. 
  

  

  Farther 
  out 
  to 
  sea 
  the 
  ashes, 
  with 
  the 
  interbedded 
  limestones, 
  

   are 
  covered 
  by 
  fine 
  green 
  and 
  purple 
  andesites. 
  

  

  The 
  martello 
  tower, 
  forming 
  the 
  Coastguard 
  station, 
  stands 
  on 
  

   a 
  mass 
  of 
  limestone 
  which 
  is 
  shaly 
  in 
  places, 
  especially 
  at 
  its 
  base, 
  

   and 
  yielded, 
  at 
  the 
  spot 
  marked 
  B 
  in 
  the 
  map, 
  Orthis 
  testudinaria, 
  

   Dalm., 
  and 
  Plectambonites 
  sericea, 
  Sow. 
  Though 
  the 
  evidence 
  is 
  

   not 
  very 
  clear, 
  this 
  mass 
  of 
  limestone 
  seems 
  to 
  dip 
  landward, 
  and 
  

   to 
  be 
  separated 
  by 
  a 
  thrust-plane 
  or 
  fault, 
  with 
  a 
  low 
  hade, 
  from 
  

   the 
  volcanic 
  series, 
  whose 
  general 
  dip 
  is, 
  as 
  mentioned 
  above, 
  

   seaward. 
  A 
  thrust- 
  or 
  fault-conglomerate 
  of 
  considerable 
  width 
  is 
  

   seen 
  at 
  the 
  junction 
  between 
  the 
  limestone 
  and 
  the 
  volcanic 
  series, 
  

   both 
  to 
  the 
  east 
  and 
  north-east 
  of 
  the 
  martello 
  tower, 
  while 
  to 
  the 
  

   south-east 
  it 
  is 
  not 
  seen. 
  

  

  The 
  volcanic 
  series 
  in 
  the 
  neighbourhood 
  of 
  this 
  plane 
  of 
  thrust 
  

   or 
  fault 
  is 
  exceedingly 
  disturbed, 
  the 
  evidence 
  of 
  crushing 
  obtained 
  

   in 
  the 
  field 
  being 
  corroborated 
  by 
  microscopic 
  examination, 
  which 
  

   shows 
  that, 
  though 
  no 
  mineralogical 
  reconstruction 
  has 
  gone 
  on, 
  

   yet 
  displacement 
  of 
  the 
  particles 
  in 
  the 
  groundmass 
  has 
  occurred. 
  

   South-east 
  of 
  the 
  martello 
  tower 
  the 
  general 
  strike 
  becomes 
  more 
  

   nearly 
  north-north-east 
  and 
  south-south-west 
  than 
  north-east 
  and 
  

   south-west. 
  Due 
  south 
  of 
  the 
  tower, 
  exposed 
  only 
  at 
  low 
  tide, 
  is 
  a 
  

   band 
  of 
  dark-grey 
  earthy 
  shales, 
  apparently 
  belonging 
  to 
  the 
  

   volcanic 
  series. 
  This 
  is 
  indicated 
  in 
  the 
  map 
  (PI. 
  XLIII) 
  by 
  the 
  

   term 
  ' 
  trilobite-shale,' 
  and 
  yielded 
  

  

  Agnoshis 
  agnostiformis, 
  M'Coy. 
  

  

  ( 
  = 
  trinodus), 
  Salt. 
  

   Ampyx 
  sp. 
  

  

  Asaphus 
  radiatus, 
  Salt. 
  ? 
  

   Cheirurus 
  juvenis, 
  Salt. 
  ? 
  

   Cybele, 
  sp 
  ? 
  

   Lichas 
  laxatus, 
  M'Coy. 
  

  

  Phacops 
  Brongniarti, 
  Portl. 
  

   Trinucleus 
  seticornis, 
  var. 
  portrain- 
  

  

  ensis, 
  Tar. 
  nov. 
  

   Orthis 
  sp. 
  

   Hyolithus 
  sp. 
  

   Glyptocystiies 
  cf. 
  Logani, 
  Billings. 
  

  

  Owing 
  to 
  the 
  thrust-plane 
  or 
  fault 
  above 
  mentioned, 
  and 
  a 
  break 
  

   in 
  the 
  continuity 
  of 
  the 
  exposure 
  in 
  the 
  sandy 
  bay 
  south 
  of 
  the 
  

   tower, 
  it 
  is 
  clear 
  that 
  no 
  regular 
  succession 
  can 
  be 
  traced 
  at 
  the 
  

   northern 
  end 
  of 
  the 
  Portraine 
  section 
  between 
  the 
  volcanic 
  series 
  as 
  

   a 
  whole 
  and 
  the 
  limestone 
  series. 
  

  

  As 
  will 
  be 
  seen 
  below, 
  a 
  well-marked 
  thrust-conglomerate 
  occurs 
  at 
  

  

  