﻿GEOLOGY. 
  87 
  

  

  resemble 
  shale 
  in 
  its 
  thin 
  stratification, 
  the 
  great 
  difference 
  being 
  in 
  

   the 
  siliceous 
  instead 
  of 
  argillaceous 
  composition: 
  Locally 
  there 
  are 
  

   beds 
  of 
  clayey 
  nature 
  in 
  the 
  upper 
  division 
  which 
  form 
  a 
  connecting 
  

   link 
  between 
  the 
  ' 
  ' 
  chalk 
  rock," 
  as 
  the 
  diatomaceous 
  shale 
  is 
  colloquially 
  

   termed, 
  and 
  common 
  clay 
  shale. 
  Characteristic 
  oval 
  and 
  lenticular 
  

   yellow 
  concretions 
  of 
  hard 
  lime 
  are 
  commonly 
  included 
  in 
  the 
  shale 
  

   of 
  the 
  upper 
  division. 
  They 
  range 
  in 
  diameter 
  from 
  a 
  few 
  inches 
  to 
  2 
  

   feet 
  or 
  more. 
  In 
  many 
  places 
  they 
  occur 
  at 
  irregular 
  intervals 
  and 
  

   of 
  irregular 
  size 
  along 
  a 
  bedding 
  plane, 
  locally 
  displacing 
  the 
  ordinary 
  

   shale 
  and 
  interrupting 
  the 
  continuity 
  of 
  not 
  merely 
  one 
  bed 
  but 
  many 
  

   thin 
  beds. 
  They 
  are 
  invariably 
  elongated 
  parallel 
  with 
  the 
  bedding. 
  

  

  Volcanic 
  ash 
  is 
  interbedded 
  with 
  the 
  soft 
  shale 
  of 
  the 
  upper 
  divi- 
  

   sion 
  in 
  the 
  hills 
  immediately 
  south 
  of 
  Lompoc. 
  It 
  is 
  very 
  fine 
  grained, 
  

   soft, 
  and 
  uncomp 
  acted, 
  and 
  probably 
  corresponds 
  in 
  composition 
  to 
  

   rhyolite. 
  It 
  somewhat 
  resembles 
  the 
  pulverulent 
  diatomaceous 
  earth, 
  

   but 
  is 
  easily 
  distinguishable 
  by 
  its 
  grayish 
  color 
  and 
  grittiness. 
  

  

  The 
  upper 
  portion 
  of 
  the 
  Monterey, 
  like 
  the 
  lower, 
  is 
  to 
  a 
  large 
  

   extent 
  impregnated 
  with 
  bituminous 
  material. 
  It 
  is 
  apt 
  almost 
  

   anywhere 
  in 
  this 
  region 
  to 
  give 
  out 
  a 
  bituminous 
  odor 
  when 
  broken 
  

   into 
  or 
  to 
  show 
  a 
  brownish 
  discoloration 
  due 
  to 
  the 
  presence 
  of 
  oil. 
  

   In 
  places 
  the 
  shale, 
  otherwise 
  white, 
  is 
  specked 
  with 
  minute 
  black 
  

   spots 
  of 
  bitumen. 
  Thin 
  sandy 
  layers 
  occur 
  sparingly 
  interbedded 
  

   with 
  the 
  shale, 
  and 
  these 
  almost 
  without 
  exception 
  have 
  absorbed 
  

   considerable 
  oil 
  and 
  have 
  a 
  dark-brown 
  color 
  and 
  strong 
  odor. 
  But 
  

   these 
  beds 
  of 
  sand 
  are 
  very 
  rare 
  and 
  make 
  up 
  no 
  appreciable 
  propor- 
  

   tion 
  of 
  the 
  series. 
  

  

  The 
  soft 
  varieties 
  of 
  the 
  Monterey 
  shale 
  are 
  almost 
  invariably 
  

   alkaline 
  and 
  have 
  a 
  salty 
  taste. 
  They 
  contain 
  an 
  abundance 
  of 
  

   salts 
  easily 
  soluble 
  in 
  water 
  that 
  form 
  characteristic 
  wooly 
  coatings 
  

   of 
  efflorescence 
  on 
  the 
  surface 
  of 
  outcrops. 
  This 
  is 
  especially 
  true 
  

   near 
  the 
  summit 
  of 
  the 
  formation, 
  where 
  a 
  soft 
  claylike 
  gypsum- 
  

   bearing 
  shale 
  locally 
  marks 
  the 
  contact 
  with 
  the 
  Fernando 
  above. 
  

   This 
  gypsum 
  is 
  crystallized 
  in 
  plates 
  along 
  seams 
  and 
  bedding 
  planes 
  

   much 
  like 
  the 
  gypsiferous 
  clay 
  of 
  the 
  Casmalia 
  Hills, 
  which 
  is 
  sup- 
  

   posed 
  to 
  be 
  Vaqueros 
  in 
  age. 
  Zones 
  of 
  gypsiferous 
  shale 
  occur 
  also 
  

   at 
  other 
  places 
  in 
  the 
  upper 
  division 
  of 
  the 
  Monterey, 
  but 
  it 
  is 
  not 
  

   known 
  whether 
  there 
  are 
  any 
  single 
  horizons 
  at 
  which 
  it 
  is 
  constant. 
  

   Where 
  the 
  gypsum 
  occurs 
  the 
  shale 
  is 
  usually 
  of 
  more 
  argillaceous 
  

   character 
  and 
  bears 
  a 
  closer 
  resemblance 
  to 
  ordinary 
  clay 
  shales. 
  

   The 
  significance 
  of 
  this 
  alkalinity 
  in 
  the 
  Monterey 
  is 
  unknown. 
  

   The 
  organic 
  shale 
  is 
  considered 
  to 
  be 
  of 
  marine 
  origin 
  in 
  fairly 
  deep 
  

   water, 
  and 
  owing 
  to 
  the 
  almost 
  complete 
  absence 
  of 
  all 
  but 
  the 
  

   finest 
  grained 
  detritus 
  the 
  alkalinity 
  can 
  not 
  be 
  considered 
  as 
  proof 
  

   of 
  shallow-water 
  or 
  brackish-water 
  origin. 
  The 
  salts 
  may 
  have 
  

   some 
  relation 
  to 
  the 
  chemical 
  changes 
  involved 
  in 
  the 
  production" 
  of 
  

   petroleum. 
  

  

  