﻿UPPER 
  CRETACEOUS 
  SERIES 
  (IGNEOUS) 
  . 
  51 
  

  

  The 
  basin 
  in 
  which 
  the 
  marine 
  cretaceous 
  deposits 
  near 
  Barwai 
  were 
  

   deposited 
  was 
  probably 
  distinct 
  from 
  that 
  to 
  the 
  west 
  of 
  Mandu, 
  but 
  

   like 
  the 
  latter 
  probably 
  deepened 
  to 
  the 
  south-west 
  also. 
  

  

  CHAPTER 
  IX. 
  

  

  Upper 
  Cretaceous 
  Series. 
  

   (Igneous.) 
  

  

  Lithology. 
  — 
  I 
  have 
  little 
  to 
  add 
  to 
  the 
  general 
  lithology 
  of 
  the 
  

   remarkable 
  series 
  of 
  horizontally-bedded 
  igneous 
  rocks 
  so 
  well 
  known 
  

   under 
  the 
  name 
  of 
  "Deccan 
  Trap." 
  The 
  alternation 
  of 
  basalt 
  with 
  

   vesicular 
  or 
  amygdaloidal 
  rocks 
  of 
  similar 
  composition, 
  and 
  the 
  abund- 
  

   ance 
  of 
  zeolitic 
  and 
  calcareous 
  minerals 
  of 
  various 
  forms 
  and 
  sizes, 
  and 
  

   of 
  geodes 
  of 
  agate 
  or 
  chalcedony 
  frequently 
  filled 
  with 
  crystals 
  of 
  

   quartz, 
  are 
  too 
  characteristic 
  to 
  have 
  escaped 
  the 
  attention 
  of 
  earlier 
  

   observers, 
  such 
  as 
  Dangerfield 
  1 
  and 
  Fraser. 
  2 
  

  

  The 
  rocks 
  which 
  have 
  been 
  referred 
  to 
  this 
  series 
  are 
  nearly 
  all 
  basic. 
  

   Those 
  forming 
  dykes 
  are 
  more 
  or 
  less 
  crystalline, 
  invariably 
  more 
  so 
  

   in 
  the 
  centre 
  than 
  at 
  the 
  sides. 
  They 
  occasionally 
  occur 
  in 
  columns, 
  

   but 
  the 
  usual 
  form 
  is 
  massive. 
  The 
  principal 
  constituents 
  are 
  plagio- 
  

   clastic 
  felspar, 
  augite 
  (mostly 
  as 
  grains) 
  , 
  and 
  magnetite. 
  The 
  first 
  is 
  

   the 
  most 
  abundant 
  and 
  conspicuous, 
  and 
  sometimes 
  occurs 
  in 
  large 
  

   crystals. 
  

  

  Lavas. 
  — 
  These 
  form 
  the 
  Malwa 
  plateau. 
  They 
  generally 
  occur 
  in 
  

   beds 
  of 
  compact 
  basalt 
  with 
  an 
  amygdaloidal 
  upper 
  portion. 
  Several 
  

   such 
  beds 
  may 
  be 
  counted 
  at 
  Jam 
  Ghat 
  where 
  the 
  winding 
  road 
  well 
  

   exposes 
  them 
  to 
  observation. 
  The 
  basalt 
  has 
  a 
  micro-crystalline 
  structure 
  

  

  1 
  Malcolm's 
  " 
  Central 
  India/' 
  Vol. 
  II, 
  pp. 
  328, 
  &c, 
  " 
  Geol. 
  Pap. 
  on 
  West 
  Ind.," 
  p. 
  231. 
  

  

  2 
  Geol. 
  Trans., 
  Ser. 
  2, 
  Vol. 
  I, 
  pp. 
  116, 
  &c. 
  

  

  The 
  descriptions 
  of 
  Sykes 
  (Geol. 
  Trans., 
  Ser. 
  2, 
  Vol, 
  IV, 
  pp. 
  411, 
  &c.) 
  and 
  Malcolmson 
  

   (Geol. 
  Trans., 
  Ser. 
  2, 
  Vol. 
  V, 
  pp. 
  537, 
  &c), 
  though 
  referring 
  particularly 
  fto 
  the 
  Deccan 
  and 
  

   Central 
  Provinces, 
  are 
  also 
  partially 
  applicable 
  to 
  the 
  general 
  lithology 
  of 
  the 
  trap 
  formation 
  

   in 
  the 
  Malwa 
  area. 
  

  

  ( 
  51 
  ) 
  

  

  