﻿76 
  SANTA 
  MARIA 
  OIL 
  DISTRICT, 
  CALIFORNIA. 
  

  

  For 
  convenience 
  the 
  two 
  quadrangles 
  will 
  be 
  divided 
  into 
  the 
  three 
  

   naturally 
  separated 
  portions 
  outlined 
  in 
  a 
  preceding 
  paragraph, 
  viz, 
  

   the 
  region 
  of 
  the 
  San 
  Rafael 
  Range, 
  which 
  includes 
  all 
  of 
  the 
  territory 
  

   northeast 
  of 
  the 
  Santa 
  Maria 
  Valley 
  and 
  a 
  line 
  extending 
  southeast 
  

   of 
  its 
  head; 
  the 
  region 
  of 
  the 
  Santa 
  Ynez 
  Range; 
  and 
  the 
  province 
  

   of 
  low 
  hills 
  and 
  shallow 
  valleys 
  intervening 
  between 
  the 
  two 
  moun- 
  

   tain 
  masses. 
  The 
  reading 
  of 
  the 
  following 
  paragraphs 
  describing 
  the 
  

   structure 
  of 
  various 
  areas 
  should 
  be 
  accompanied 
  by 
  reference 
  to 
  the 
  

   map. 
  (PL 
  I, 
  in 
  pocket.) 
  For 
  the 
  sake 
  of 
  compactness 
  the 
  conclu- 
  

   sions 
  as 
  to 
  the 
  possibilities 
  of 
  productiveness 
  of 
  the 
  Monterey 
  shale 
  

   have 
  been 
  stated, 
  together 
  with 
  the 
  description 
  of 
  its 
  main 
  structural 
  

   features. 
  

  

  It 
  must 
  be 
  remembered 
  that 
  in 
  regions 
  of 
  great 
  disturbance 
  such 
  as 
  

   the 
  shales 
  have 
  undergone 
  in 
  some 
  parts 
  of 
  the 
  area 
  it 
  is 
  difficult 
  to 
  

   represent 
  by 
  single 
  lines 
  the 
  complexity 
  of 
  the 
  structure. 
  Some 
  of 
  

   the 
  lines, 
  therefore, 
  mark 
  zones 
  of 
  folding 
  rather 
  than 
  single 
  definitely 
  

   continuous 
  folds. 
  The 
  dotted 
  lines 
  of 
  structure 
  are 
  purely 
  supposi- 
  

   tional. 
  

  

  REGION 
  OF 
  THE 
  SAN 
  RAFAEL 
  MOUNTAINS. 
  

   AREAS 
  OF 
  ROCKS 
  OLDER 
  THAN 
  THE 
  MONTEREY. 
  

  

  Whatever 
  succession 
  of 
  beds 
  or 
  structural 
  conditions 
  may 
  once 
  

   have 
  existed 
  in 
  the 
  Franciscan 
  formation 
  (Jurassic?) 
  in 
  this 
  district, 
  

   .they 
  have 
  been 
  largely 
  obliterated 
  by 
  the 
  successive 
  folding 
  and 
  

   crushing 
  to 
  which 
  these 
  rocks 
  have 
  been 
  subjected 
  in 
  the 
  long 
  period 
  

   of 
  time 
  since 
  their 
  first 
  uplift. 
  The 
  shales 
  and 
  sandstones 
  mapped 
  as 
  

   pre-Monterey, 
  especially 
  where 
  the 
  beds 
  alternate, 
  have 
  preserved 
  the 
  

   folds 
  well, 
  but 
  except 
  on 
  North 
  Fork 
  of 
  Labrea 
  Creek 
  and 
  along 
  Sis- 
  

   quoc 
  River 
  no 
  effort 
  has 
  been 
  made 
  to 
  work 
  out 
  the 
  structure 
  of 
  tins 
  

   series. 
  

  

  AREAS 
  OF 
  MONTEREY 
  AND 
  LATER 
  FORMATIONS. 
  

   FOLDS. 
  

  

  Considered 
  as 
  a 
  whole 
  the 
  Monterey 
  has 
  been 
  thrown 
  into 
  a 
  series 
  

   of 
  anticlinal 
  and 
  synclinal 
  folds 
  striking 
  about 
  N. 
  50° 
  W., 
  and 
  appar- 
  

   ently 
  plunging, 
  in 
  the 
  main, 
  toward 
  the 
  northwest. 
  Great 
  variation 
  

   exists 
  in 
  the 
  relative 
  steepness 
  of 
  dip 
  along 
  these 
  folds, 
  but 
  it 
  is 
  evident 
  

   that 
  the 
  compressive 
  forces 
  producing 
  them 
  were 
  of 
  much 
  greater 
  

   strength 
  in 
  the 
  southeastern 
  part 
  of 
  the 
  area, 
  between 
  Bone 
  Mountain 
  

   and 
  Round 
  Corral 
  Canyon 
  and 
  thence 
  southeastward 
  into 
  the 
  region 
  

   of 
  Zaca 
  Peak. 
  Here 
  the 
  folds 
  become 
  so 
  compressed 
  and 
  in 
  places 
  

   overturned 
  that 
  it 
  is 
  difficult 
  to 
  trace 
  them. 
  PL 
  III, 
  B 
  (p. 
  34) 
  and 
  

   VI, 
  B 
  (p. 
  46) 
  give 
  an 
  idea 
  of 
  the 
  closeness 
  of 
  the 
  folding. 
  In 
  contrast 
  

   with 
  this 
  constricted 
  portion 
  is 
  the 
  broad 
  series 
  of 
  folds 
  which 
  extend 
  

  

  