﻿548 
  DR. 
  W. 
  FEASEE 
  HUME 
  ON 
  [Dec. 
  1897, 
  

  

  (2) 
  The 
  Centeal 
  Division. 
  

   From 
  White 
  Mountain 
  to 
  Cave 
  Hill. 
  

  

  The 
  first 
  indication 
  of 
  a 
  change 
  in 
  the 
  character 
  of 
  the 
  strata 
  

   underlying 
  the 
  White 
  Chalk 
  is 
  a 
  remark 
  in 
  the 
  Geological 
  Survey 
  

   Memoir, 
  Expl. 
  Sheet 
  36, 
  p. 
  29 
  : 
  ' 
  JSiorth 
  of 
  the 
  cross-roads, 
  S.W. 
  of 
  

   Castle 
  Robin, 
  a 
  reddish 
  sandy 
  rock 
  may 
  he 
  seen, 
  containing 
  fragments 
  

   oilnocerami 
  : 
  this 
  is 
  probably 
  the 
  upper 
  portion 
  of 
  the 
  Greensand 
  ; 
  ' 
  

   and 
  near 
  Groganstown, 
  still 
  farther 
  north, 
  are 
  ' 
  12 
  feet 
  of 
  greenish- 
  

   grey 
  mulatto-stone, 
  containing 
  small 
  pebbles 
  of 
  quartz 
  in 
  such 
  

   numbers 
  that 
  it 
  might 
  with 
  propriety 
  be 
  termed 
  a 
  fine 
  conglomerate.' 
  

  

  Colin 
  Mountain. 
  

  

  On 
  the 
  sides 
  of 
  Colin 
  Mountain, 
  a 
  large 
  limestone-quarry 
  is 
  being 
  

   worked, 
  to 
  the 
  south-west 
  of 
  which 
  a 
  small 
  stream 
  runs 
  in 
  a 
  deep 
  

   groove, 
  cut 
  in 
  the 
  Cretaceous 
  rocks. 
  Here 
  the 
  lowest 
  Cretaceous 
  

   beds, 
  the 
  Glauconitic 
  Sands, 
  are 
  well 
  exposed, 
  a 
  central 
  band, 
  3 
  feet 
  

   thick, 
  full 
  of 
  Eocogyra 
  conica, 
  var. 
  laevigata, 
  Sow., 
  being 
  very 
  con- 
  

   spicuous. 
  Pecten 
  [Janira~] 
  quinquecostatus, 
  Sow., 
  P. 
  \_Amussium~] 
  

   orbicularis 
  (Mant.), 
  and 
  Avicula, 
  near 
  lineata, 
  Rom., 
  occur 
  sparingly 
  

   in 
  the 
  band 
  itself, 
  but 
  a 
  little 
  above 
  it 
  are 
  more 
  numerous. 
  A 
  

   fragment 
  of 
  an 
  ammonite, 
  most 
  probably 
  Hoplites 
  catillus, 
  Sow., 
  

   was 
  also 
  obtained. 
  These 
  beds 
  pass 
  into 
  sands 
  of 
  a 
  brownish-red 
  

   colour 
  above, 
  and 
  into 
  unfossiliferous 
  deep-green 
  sands 
  below. 
  Many 
  

   pebbles 
  of 
  small 
  size 
  are 
  scattered 
  throughout 
  the 
  series. 
  The 
  total 
  

   thickness 
  of 
  these 
  strata 
  is 
  at 
  least 
  12 
  feet, 
  so 
  that 
  this 
  locality 
  

   presents 
  not 
  only 
  the 
  most 
  southerly, 
  but 
  also 
  the 
  best 
  developed 
  

   exposure 
  of 
  these 
  rocks, 
  which, 
  as 
  we 
  shall 
  see 
  later, 
  are 
  of 
  Upper 
  

   Greensand 
  age. 
  They 
  appear 
  to 
  correspond 
  to 
  the 
  ' 
  glaucous 
  marls' 
  of 
  

   Expl. 
  Sheet 
  36, 
  p. 
  28. 
  A 
  bridge 
  crossing 
  the 
  stream, 
  and 
  a 
  waterfall, 
  

   prevent 
  a 
  close 
  examination 
  of 
  the 
  Yellow 
  Sandstone, 
  which 
  rests 
  

   upon 
  the 
  strata 
  just 
  described. 
  

  

  Higher 
  up 
  the 
  stream, 
  above 
  the 
  bridge, 
  there 
  are 
  loose 
  greenish- 
  

   yellow 
  sands, 
  which 
  pass 
  into 
  a 
  glauconitic 
  sandstone, 
  containing 
  

   unidentifiable 
  sponge-remains. 
  In 
  the 
  limestone-quarry 
  itself, 
  some 
  

   50 
  feet 
  of 
  White 
  Chalk 
  is 
  exposed, 
  containing 
  Belem.nitella 
  mucro- 
  

   nata, 
  Schloth., 
  and 
  Terebratula 
  cornea, 
  Sow., 
  but 
  otherwise 
  presenting 
  

   no 
  features 
  of 
  interest. 
  Mr. 
  Bell 
  has 
  obtained 
  Terebratula 
  obesa, 
  

   Sow., 
  and 
  Ostrea 
  vesicularis, 
  Lam., 
  at 
  this 
  locality. 
  

  

  Colin 
  Glen. 
  

  

  The 
  section 
  in 
  this 
  glen, 
  which 
  is 
  one 
  of 
  the 
  most 
  complete 
  in 
  

   this 
  part 
  of 
  the 
  country, 
  has 
  been 
  especially 
  referred 
  to 
  by 
  Prof. 
  Tate. 
  

   Owing 
  to 
  repeated 
  faulting, 
  the 
  Trias, 
  Lias, 
  and 
  Cretaceous 
  are 
  

   traversed 
  several 
  times 
  in 
  ascending 
  the 
  stream, 
  so 
  that 
  the 
  accuiaey 
  

   of 
  the 
  succession 
  can 
  be 
  carefully 
  tested. 
  

  

  The 
  red 
  and 
  green 
  sandstones 
  and 
  marls 
  of 
  the 
  Trias 
  form 
  the 
  

   base 
  of 
  the 
  series 
  at 
  this 
  locality. 
  Above 
  these 
  follow 
  the 
  Rhsetic 
  

  

  