﻿44 
  SANTA 
  MARIA 
  OIL 
  DISTRICT, 
  CALIFORNIA. 
  

  

  incipient 
  crystallization, 
  are 
  included 
  in 
  the 
  clear 
  bands, 
  giving 
  a 
  brec- 
  

   ciated 
  appearance. 
  The 
  bands 
  are 
  parallel 
  with 
  the 
  bedding 
  planes. 
  

   They 
  are 
  commonly 
  followed 
  and 
  more 
  rarely 
  crossed 
  by 
  veins 
  of 
  

   quartz 
  crystals. 
  

  

  The 
  limestone 
  is 
  made 
  up 
  of 
  granules 
  of 
  crystalline 
  calcite, 
  or 
  cal- 
  

   cite 
  showing 
  the 
  beginnings 
  of 
  crystallization. 
  Included 
  in 
  this 
  

   extremely 
  line 
  grained, 
  uniform 
  groundmass 
  are 
  larger 
  but 
  yet 
  very 
  

   small, 
  irregular 
  grains 
  of 
  crystalline 
  calcite, 
  and 
  in 
  places 
  long 
  spicules 
  

   of 
  the 
  same. 
  In 
  some 
  specimens 
  the 
  granules 
  are 
  more 
  minute 
  than 
  

   in 
  others 
  and 
  the 
  included 
  larger 
  grains 
  are 
  fewer. 
  In 
  still 
  others, 
  

   crystallization 
  has 
  entirely 
  altered 
  portions 
  into 
  patches 
  of 
  large, 
  

   intergrown 
  crystals, 
  leaving 
  angular, 
  unchanged 
  patches 
  sharply 
  

   marked 
  off, 
  and 
  thus 
  giving 
  an 
  appearance 
  like 
  that 
  of 
  a 
  breccia. 
  

   The 
  flinty 
  calcareous 
  shale 
  has 
  a 
  minute 
  granular 
  texture, 
  quartz 
  

   grains 
  both 
  crystalline 
  and 
  semicrystalline 
  being 
  associated 
  with 
  those 
  

   of 
  calcite. 
  The 
  rock 
  usually 
  has 
  light 
  and 
  dark 
  bands 
  parallel 
  with 
  

   the 
  bedding, 
  the 
  light 
  bands 
  containing 
  more 
  quartz 
  and 
  having 
  the 
  

   calcite 
  granules 
  less 
  close 
  together 
  than 
  the 
  darker 
  bands. 
  

  

  CHEMICAL 
  COMPOSITION. 
  

  

  The 
  subjoined 
  table 
  comprises 
  analyses 
  of 
  different 
  specimens 
  and 
  

   varieties 
  of 
  Monterey 
  shale 
  from 
  the 
  Santa 
  Maria 
  district, 
  with 
  one 
  

   (No. 
  5) 
  here 
  included 
  for 
  comparison, 
  of 
  a 
  sample 
  of 
  white 
  bitumin- 
  

   ous 
  shale 
  from 
  the 
  type 
  locality 
  of 
  the 
  formation 
  at 
  Monterey, 
  farther 
  

   north 
  on 
  the 
  California 
  coast. 
  

  

  The 
  first 
  three 
  represent 
  typical 
  examples 
  of 
  the 
  unaltered 
  diato- 
  

   maceous 
  shale 
  of 
  the 
  Monterey. 
  Nos. 
  3 
  and 
  2, 
  respectively, 
  are 
  analy- 
  

   ses 
  of 
  the 
  same 
  samples 
  that 
  were 
  found 
  to 
  be 
  rich 
  in 
  diatoms 
  when 
  

   examined 
  in 
  slides 
  1 
  and 
  2 
  by 
  Messrs. 
  Keeley 
  and 
  Boyer, 
  as 
  mentioned 
  

   on 
  pages 
  40-41. 
  Nos. 
  4 
  and 
  6 
  are 
  analyses 
  of 
  samples 
  from 
  the 
  same 
  

   hand 
  specimen, 
  taken 
  within 
  1 
  inch 
  of 
  each 
  other, 
  No. 
  4 
  showing 
  the 
  

   composition 
  of 
  unaltered 
  white 
  shale 
  in 
  which 
  diatoms 
  are 
  visible, 
  and 
  

   No. 
  6 
  of 
  the 
  translucent, 
  brittle, 
  flintlike 
  product 
  of 
  extremely 
  local 
  

   alteration. 
  The 
  next 
  four 
  indicate 
  gradations 
  in 
  the 
  products 
  of 
  the 
  

   metamorphism. 
  The 
  last 
  analysis 
  (No. 
  11) 
  represents 
  limestone 
  

   typical 
  in 
  lithologic 
  appearance 
  of 
  the 
  limestone 
  of 
  the 
  Monterey. 
  

  

  