﻿94 
  PROCEEDINGS 
  OF 
  THE 
  GEOLOGICAL 
  SOCIETY. 
  

  

  One 
  or 
  two 
  of 
  these 
  zones, 
  although 
  present, 
  are 
  not 
  fully 
  repre- 
  

   sented 
  in 
  Rutland 
  ; 
  such 
  appears 
  to 
  be 
  the 
  case 
  with 
  the 
  zone 
  of 
  

   Am. 
  obtusus 
  ; 
  but, 
  taking 
  type 
  localities 
  for 
  our 
  guide, 
  each 
  zone 
  is, 
  

   in 
  its 
  geographical 
  place 
  or 
  locality, 
  characteristically 
  shown. 
  This 
  

   obscurely 
  developed 
  Obtusus 
  series 
  in 
  Rutlandshire 
  is 
  at 
  Lyme 
  Regis 
  

   a 
  marked 
  and 
  important 
  horizon 
  in 
  the 
  Lower 
  Lias. 
  The 
  same 
  may 
  

   be 
  said 
  of 
  the 
  zone 
  of 
  " 
  Ibex 
  " 
  in 
  Somersetshire 
  ; 
  it 
  is 
  well 
  developed, 
  

   and 
  known 
  under 
  the 
  name 
  of 
  A. 
  BoUayei. 
  This 
  and 
  the 
  zone 
  of 
  

   Am. 
  Jamesoni 
  are 
  often 
  united*. 
  

  

  The 
  thirty-two 
  pages 
  in 
  Prof. 
  Judd's 
  memoir 
  devoted 
  to 
  the 
  

   Lias, 
  demonstrate 
  the 
  value 
  of 
  the 
  above 
  divisions, 
  and 
  enable 
  the 
  

   student 
  to 
  correlate 
  the 
  English 
  Lias 
  with 
  that 
  of 
  the 
  continent. 
  

   The 
  zones 
  of 
  Am. 
  Miuxhisonce, 
  Am. 
  Humphresianus, 
  and^Lra. 
  Parkin- 
  

   soni 
  equally 
  in 
  their 
  order 
  characterize 
  the 
  Inferior 
  Oolite, 
  Am. 
  

   gracilis 
  the 
  Great 
  Oolite, 
  and 
  Am. 
  discus 
  and 
  mncrocephalus 
  the 
  

   Cornbrash 
  ; 
  the 
  preceding 
  formations 
  are 
  all 
  equally 
  capable 
  of 
  zonal 
  

   subdivision 
  by 
  means 
  of 
  their 
  characteristic 
  Ammonites. 
  

  

  The 
  chapter 
  devoted 
  to 
  the 
  Lower 
  Oolites 
  sets 
  forth 
  the 
  received 
  

   subdivisions, 
  and 
  establishes 
  the 
  grouping 
  of 
  the 
  Inferior 
  Oolite 
  into 
  

   two 
  members, 
  the 
  lower 
  being 
  chiefly 
  arenaceous, 
  and 
  constituting 
  

   the 
  " 
  Northampton 
  Sand 
  ;" 
  while 
  the 
  upper 
  division 
  is 
  almost 
  purely 
  

   calcareous, 
  and 
  is 
  distinguished 
  by 
  the 
  name 
  of 
  the 
  " 
  Lincolnshire 
  

   Oolite 
  Limestones." 
  Here 
  and 
  there, 
  at 
  the 
  junction 
  of 
  these 
  two 
  

   groups, 
  there 
  occur 
  beds 
  of 
  fissile 
  sandy 
  limestone. 
  These 
  slaty 
  

   beds 
  constitute 
  the 
  " 
  Colly 
  weston 
  Slates," 
  hitherto 
  wrongly 
  referred 
  

   to 
  the 
  base 
  of 
  the 
  Great 
  Oolite. 
  

  

  The 
  Great 
  Oolite 
  strata 
  are 
  divisible 
  into 
  four 
  groups 
  : 
  — 
  

  

  No. 
  1, 
  or 
  the 
  highest, 
  being 
  the 
  Cornbrash. 
  

  

  2, 
  the 
  Great 
  Oolite 
  Clay 
  = 
  the 
  Forest 
  Marble 
  of 
  the 
  south 
  

   of 
  England. 
  

  

  3, 
  the 
  Great 
  Oolite 
  Limestones. 
  

  

  4, 
  the 
  Upper 
  Estuarine 
  marls 
  &c. 
  which 
  represent 
  the 
  Stones- 
  

  

  field 
  Slate 
  or 
  lower 
  zone 
  of 
  the 
  Great 
  Oolite 
  of 
  the 
  south 
  

   of 
  England. 
  

  

  Beneath 
  these 
  Upper 
  Estuarine 
  beds 
  comes 
  the 
  Lincolnshire 
  Lime- 
  

   stone, 
  containing 
  the 
  characteristic 
  fossils 
  of 
  the 
  lowest 
  division, 
  or 
  

   the 
  Inferior 
  Oolite 
  of 
  the 
  south-west 
  of 
  England. 
  Succeeding 
  the 
  

   above, 
  or 
  forming 
  its 
  lowest 
  member, 
  is 
  the 
  Northampton 
  Sand, 
  asso- 
  

   ciated 
  with 
  which 
  in 
  the 
  upper 
  part 
  is 
  the 
  Lower 
  Estuarine 
  series. 
  

   The 
  Northampton 
  Sand 
  often 
  reposes 
  upon 
  an 
  eroded 
  surface 
  of 
  

   Upper 
  Lias 
  clay. 
  The 
  fossils 
  of 
  the 
  Lower 
  Ironstone 
  are 
  all 
  marine 
  f. 
  

   Forty-eight 
  pages 
  are 
  devoted 
  to 
  the 
  .origin, 
  general 
  features, 
  litho- 
  

   logical 
  characters, 
  microscopical 
  structure, 
  and 
  mode 
  of 
  formation 
  of 
  

   the 
  Northamptonshire 
  iron-ore. 
  

  

  The 
  following 
  list 
  exhibits 
  the 
  number 
  of 
  fossils 
  of 
  the 
  Ironstone 
  

  

  * 
  Vide 
  paper 
  by 
  E. 
  B. 
  Tawney, 
  M.A., 
  Proc. 
  Bristol 
  Nat. 
  Soc. 
  1875. 
  

   t 
  The 
  largest 
  collection 
  ever 
  made 
  of 
  the 
  fossils 
  of 
  this 
  series 
  was 
  by 
  Mr. 
  S. 
  

   Sharp, 
  F.G.S., 
  and 
  chiefly 
  from 
  Duston 
  and 
  other 
  points 
  near 
  Northampton. 
  

  

  