﻿30 
  SANTA 
  MARIA 
  OIL 
  DISTRICT, 
  CALIFORNIA. 
  

  

  its 
  rocks 
  stratigraphically 
  below 
  the 
  base 
  of 
  the 
  Monterey 
  (middle 
  

   Miocene) 
  shale. 
  

  

  Strata 
  corresponding 
  to 
  the 
  upper 
  portion 
  of 
  the 
  Tejon-Sespe- 
  

   Yaqueros 
  terrane 
  have 
  been 
  recognized 
  also 
  in 
  the 
  San 
  Rafael 
  Moun- 
  

   tains, 
  where 
  they 
  are 
  exposed 
  at 
  the 
  base 
  of 
  the 
  Monterey 
  (middle 
  

   Miocene), 
  and 
  it 
  may 
  be 
  that 
  the 
  pre-Monterey 
  rocks 
  are 
  in 
  part 
  

   equivalent 
  to 
  the 
  lower 
  portion 
  of 
  this 
  terrane. 
  The 
  Vaqueros 
  and 
  

   possibly 
  part 
  of 
  the 
  Tejon 
  are 
  present 
  also 
  in 
  the 
  Casmalia 
  Hills. 
  

  

  LITHOLOGIC 
  CHARACTER. 
  

  

  The 
  lower 
  portion 
  of 
  the 
  terrane 
  is 
  made 
  up 
  of 
  a 
  thick 
  series 
  of 
  

   greenish-gray 
  coarse 
  and 
  fine 
  sandstones, 
  many 
  of 
  them 
  concretion- 
  

   ary 
  in 
  character, 
  interbedded 
  with 
  dark, 
  fine-grained, 
  thin-bedded 
  

   shales 
  in 
  lesser 
  amount. 
  Toward 
  the 
  middle 
  of 
  the 
  terrane 
  the 
  shale 
  

   increases 
  in 
  amount, 
  alternating 
  with 
  thin 
  beds 
  of 
  sandstone. 
  Much 
  

   of 
  the 
  shale. 
  has 
  a 
  characteristic 
  olive-gray 
  color, 
  and 
  owing 
  to 
  its 
  

   hard, 
  gritty, 
  brittle 
  nature 
  it 
  makes 
  excellent 
  road, 
  material 
  for 
  the 
  

   Santa 
  Ynez 
  Valley. 
  The 
  shales 
  and 
  sandstones 
  give 
  place 
  above 
  

   the 
  middle 
  of 
  the 
  terrane 
  to 
  deposits 
  of 
  shallow-water 
  character 
  — 
  

   coarse 
  sandstone 
  and 
  a 
  great 
  quantity 
  of 
  coarse, 
  in 
  many 
  places 
  green- 
  

   ish 
  or 
  reddish, 
  gravelly 
  conglomerate. 
  This 
  conglomerate 
  contains 
  

   abundant 
  Vaqueros 
  fossils 
  and 
  probably 
  represents 
  the 
  base 
  of 
  that 
  

   formation 
  and 
  a 
  period 
  of 
  shallow-water 
  conditions 
  with 
  which 
  the 
  

   Vaqueros 
  began. 
  The 
  conglomerate 
  gives 
  place 
  in 
  turn 
  to 
  more 
  

   shale 
  and 
  sandstone, 
  which 
  continue 
  to 
  the 
  summit 
  of 
  the 
  terrane. 
  

   At 
  the 
  top 
  there 
  is 
  a 
  conformable 
  gradation 
  into 
  the 
  Monterey 
  (mid- 
  

   dle 
  Miocene) 
  beds, 
  the 
  summit 
  of 
  the 
  Vaqueros 
  being 
  marked 
  by 
  a 
  

   calcareous 
  zone 
  in 
  many 
  places 
  — 
  as, 
  for 
  instance, 
  southwest 
  of 
  Lom- 
  

   poc, 
  where 
  the 
  two 
  formations 
  are 
  divided 
  by 
  a 
  very 
  prominent 
  

   exposure 
  of 
  hard 
  limestone. 
  This 
  limestone 
  is 
  quarried 
  and 
  used 
  in 
  

   the 
  refining 
  of 
  beet 
  sugar. 
  Sandstone, 
  shale, 
  and 
  conglomerate 
  

   belonging 
  to 
  the 
  Tejon-Sespe- 
  Vaqueros 
  terrane 
  occur 
  at 
  the 
  seaward 
  

   end 
  of 
  the 
  Casmalia 
  Hills. 
  They 
  form 
  a 
  series 
  conformably 
  under- 
  

   lying 
  the 
  Monterey 
  (middle 
  Miocene) 
  ; 
  but 
  they 
  are 
  separated 
  from 
  

   beds 
  of 
  flint 
  and 
  shale 
  that 
  can 
  be 
  definitely 
  assigned 
  to 
  the 
  latter 
  

   formation 
  by 
  an 
  intervening 
  horizon 
  many 
  hundred 
  feet 
  thick 
  of 
  

   soft, 
  light-brown, 
  clayey, 
  alkaline 
  shale 
  that 
  is 
  almost 
  invariably 
  

   full 
  of 
  crystalline 
  gypsum. 
  Here 
  the 
  conditions 
  existing 
  during 
  the 
  

   period 
  of 
  transition 
  from 
  typical 
  Vaqueros 
  to 
  typical 
  Monterey 
  sedi- 
  

   mentation 
  must 
  have 
  been 
  very 
  different 
  from 
  those 
  prevalent 
  over 
  

   the 
  areas 
  occupied 
  by 
  the 
  Santa 
  Ynez 
  and 
  San 
  Rafael 
  ranges. 
  Acidic 
  

   volcanic 
  ash 
  is 
  interbedded 
  with 
  the 
  Tejon-Sespe-Vaqueros 
  strata 
  

   in 
  the 
  Casmalia 
  Hills, 
  The 
  occurrence 
  of 
  the 
  ash 
  and 
  the 
  alkaline 
  

  

  