﻿ON 
  TEE 
  UPPER 
  JURASSIC 
  CLAYS 
  OF 
  LINCOLNSHIRE. 
  545 
  

  

  34 
  The 
  Upper 
  Jurassic 
  Clays 
  of 
  Lincolnshire. 
  By 
  Thomas 
  

   Roberts, 
  Esq., 
  M.A., 
  F.G.S., 
  Woodwardian 
  Museum, 
  Cam- 
  

   bridge. 
  (Read 
  May 
  22, 
  1889.) 
  

  

  Contents. 
  

  

  1. 
  Introduction. 
  

  

  2. 
  Oxford 
  Clay. 
  

  

  3. 
  Clays 
  above 
  the 
  Oxford 
  Clay. 
  

  

  (a) 
  General 
  Description. 
  

  

  (b) 
  Correlation. 
  

  

  4. 
  Summary. 
  

  

  1. 
  Introduction. 
  

  

  The 
  broad 
  tract 
  of 
  low 
  country 
  which 
  extends 
  from 
  the 
  Humber 
  

   through 
  the 
  middle 
  portion 
  of 
  Lincolnshire, 
  and 
  spreads 
  out 
  into 
  

   the 
  fen-country 
  to 
  the 
  south, 
  is 
  underlain 
  by 
  a 
  thick 
  deposit 
  of 
  clay 
  

   which, 
  in 
  the 
  adjoining 
  county 
  of 
  Cambridgeshire, 
  has 
  been 
  called 
  

   the 
  " 
  Great 
  Pen-Clay"*. 
  The 
  lower 
  portion 
  of 
  this 
  great 
  pelolithic 
  

   formation 
  is 
  undoubtedly 
  of 
  Oxford-Clay 
  age, 
  whilst 
  its 
  upper 
  portion 
  

   certainly 
  belongs 
  to 
  the 
  Kimeridge 
  Clay. 
  Owing 
  to 
  the 
  absence 
  of 
  

   beds 
  lithologically 
  resembling 
  those 
  of 
  the 
  Corallian 
  rocks 
  of 
  York- 
  

   shire 
  and 
  the 
  southern 
  and 
  south 
  midland 
  counties 
  of 
  England, 
  no 
  

   division 
  corresponding 
  in 
  age 
  to 
  the 
  Corallian 
  has 
  as 
  yet 
  been 
  made 
  

   out 
  in 
  Lincolnshire. 
  

  

  Prof. 
  Blake 
  states 
  that 
  the 
  Kimeridge 
  and 
  Oxford 
  Clays 
  here 
  

   form 
  one 
  continuous 
  formation 
  f. 
  In 
  the 
  Survey 
  Memoir 
  on 
  this 
  

   district 
  it 
  is 
  mentioned 
  J 
  that 
  the 
  Corallian 
  group 
  is 
  entirely 
  absent, 
  

   and 
  only 
  the 
  Oxford 
  and 
  Kimeridge 
  Clays 
  are 
  mapped. 
  Jukes- 
  

   Browne 
  goes 
  still 
  further, 
  and 
  states 
  that 
  "in 
  Lincolnshire 
  there 
  

   is 
  nothing 
  to 
  represent 
  the 
  Corallian 
  group, 
  the 
  Oxford 
  Clay 
  merg- 
  

   ing 
  gradually 
  into 
  the 
  Kimeridge 
  Clay 
  " 
  §. 
  H. 
  B. 
  Woodward 
  

   mentions 
  that 
  in 
  Lincolnshire, 
  Buckinghamshire, 
  Norfolk, 
  and 
  pro- 
  

   bably 
  Sussex, 
  " 
  the 
  Kimmeridge 
  and 
  Oxford 
  Clays 
  come 
  in 
  direct 
  

   sequence," 
  and 
  he 
  adds 
  that 
  " 
  unless 
  we 
  imagine 
  an 
  unconformity 
  — 
  

   and 
  there 
  is 
  no 
  reason 
  for 
  this 
  supposition 
  — 
  the 
  Coral 
  Rag 
  and 
  

   Calcareous 
  Grit 
  developed 
  in 
  Oxfordshire, 
  Wiltshire, 
  and 
  Dorset- 
  

   shire, 
  are 
  represented 
  by 
  portions 
  of 
  the 
  Oxford 
  and 
  Kimmeridge 
  

   Clays 
  in 
  the 
  districts 
  just 
  mentioned 
  " 
  ||. 
  No 
  attempt, 
  however, 
  has 
  

   as 
  yet 
  been 
  made 
  to 
  separate 
  off 
  a 
  portion 
  which 
  would 
  be 
  equivalent 
  

   to 
  the 
  Corallian 
  of 
  other 
  areas. 
  

  

  Geologist, 
  vol. 
  ii. 
  p. 
  552. 
  

  

  t 
  Blake, 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  xxxi. 
  p. 
  216. 
  See 
  also 
  Woodward's 
  

   ' 
  Geology 
  of 
  England 
  and 
  Wales,' 
  2nd 
  ed, 
  p. 
  329. 
  

  

  \ 
  Mem. 
  Geol. 
  Surv. 
  sheet 
  83, 
  p. 
  73. 
  

  

  § 
  ' 
  Historical 
  Geology,' 
  p. 
  353. 
  

  

  || 
  Proc. 
  Geol. 
  Assoc, 
  vol. 
  iv. 
  p. 
  266. 
  

   Q.J.G.S. 
  No. 
  179. 
  2q 
  

  

  