﻿GEOLOGY. 
  65 
  

  

  and 
  believes 
  to 
  antedate 
  the 
  Knoxville. 
  It 
  is 
  closely 
  associated 
  and 
  

   intermingled 
  with 
  bodies 
  of 
  diabase 
  and 
  gabbro. 
  This 
  complex 
  

   forms 
  Point 
  Sal 
  Ridge 
  and 
  the 
  rocky 
  headland 
  of 
  Point 
  Sal. 
  Another 
  

   complex 
  that 
  he 
  believes 
  belongs 
  in 
  the 
  Knoxville 
  forms 
  a 
  long 
  dike 
  

   north 
  of 
  Schumann 
  Canyon. 
  It 
  is 
  an 
  exceedingly 
  complicated 
  intru- 
  

   sive 
  mass 
  of 
  gabbro 
  and 
  peridotite 
  that 
  has 
  been 
  penetrated 
  by 
  later 
  

   dikes 
  of 
  diabase, 
  norite, 
  gabbro, 
  and 
  intermediate 
  types 
  of 
  rock. 
  

  

  The 
  areas 
  mapped 
  as 
  Franciscan 
  (Jurassic) 
  are 
  largely 
  occupied 
  by 
  

   serpentine 
  that 
  was 
  originally 
  intruded 
  in 
  Franciscan 
  strata. 
  This 
  

   serpentine 
  may 
  be 
  older 
  than 
  the 
  Knoxville, 
  and 
  the 
  last-mentioned 
  

   occurrence 
  of 
  gabbro 
  and 
  peridotite 
  may 
  be 
  contemporaneous 
  with 
  it. 
  

  

  Diabase 
  was 
  struck 
  at 
  a 
  depth 
  of 
  1,300 
  feet 
  in 
  the 
  Pezzorii 
  well 
  

   No. 
  1, 
  southwest 
  of 
  Sisquoc. 
  It 
  is 
  a 
  considerably 
  altered 
  rock 
  com- 
  

   posed 
  largely 
  of 
  serpentine 
  and 
  plagioclase 
  feldspar, 
  with 
  some 
  augite, 
  

   possibly 
  a 
  small 
  amount 
  of 
  unaltered 
  olivine, 
  considerable 
  magnetite, 
  

   and 
  several 
  accessory 
  minerals. 
  This 
  occurrence 
  is 
  of 
  considerable 
  

   importance 
  as 
  affecting 
  the 
  prospects 
  for 
  the 
  production 
  of 
  oil 
  in 
  

   this 
  neighborhood. 
  The 
  question 
  arises 
  whether 
  this 
  diabase 
  has 
  

   intruded 
  the 
  Monterey, 
  as 
  in 
  the 
  San 
  Rafael 
  Mountains, 
  or 
  whether 
  

   it 
  is 
  a 
  part 
  of 
  the 
  older 
  igneous 
  formations, 
  in 
  which 
  diabase 
  is 
  

   common. 
  The 
  fact 
  that 
  the 
  rock 
  is 
  so 
  much 
  altered 
  probably 
  indi- 
  

   cates 
  that 
  it 
  belongs 
  to 
  a 
  formerly 
  exposed 
  older 
  formation 
  upon 
  

   which 
  a 
  fairly 
  high 
  portion 
  of 
  the 
  Monterey 
  shale 
  series 
  has 
  over- 
  

   lapped. 
  It 
  is 
  hardly 
  conceivable 
  that 
  an 
  intrusion 
  at 
  such 
  a 
  depth 
  

   in 
  the 
  shale 
  could 
  have 
  undergone 
  so 
  much 
  alteration. 
  In 
  either 
  

   case, 
  whether 
  this 
  diabase 
  marks 
  the 
  base 
  of 
  the 
  Monterey 
  or 
  whether 
  

   the 
  shales 
  have 
  been 
  intruded 
  by 
  an 
  igneous 
  mass, 
  the 
  conditions 
  are 
  

   unfavorable 
  for 
  the 
  discovery 
  of 
  oil 
  in 
  the 
  immediate 
  vicinity. 
  

  

  IGNEOUS 
  ROCKS 
  INTRUDING 
  THE 
  MONTEREY. 
  

  

  The 
  youngest 
  igneous 
  rocks 
  occurring 
  in 
  the 
  Santa 
  Maria 
  quad- 
  

   rangle 
  and 
  those 
  of 
  chief 
  interest 
  in 
  the 
  present 
  connection 
  are 
  intru- 
  

   sive 
  in 
  the 
  Monterey 
  (middle 
  Miocene) 
  . 
  Such 
  are 
  five 
  small 
  areas 
  of 
  

   diabase 
  mapped 
  by 
  Fairbanks 
  south 
  of 
  Point 
  Sal 
  and 
  two 
  areas 
  of 
  

   diabase 
  in 
  the 
  San 
  Rafael 
  Mountains. 
  The 
  age 
  of 
  the 
  two 
  latter 
  is 
  

   somewhat 
  in 
  doubt, 
  but 
  the 
  met 
  amorphic 
  and 
  disturbed 
  appearance 
  

   of 
  the 
  Monterey 
  shale 
  in 
  their 
  vicinity 
  indicates 
  that 
  they 
  originated 
  

   as 
  dikes 
  intruding 
  the 
  Monterey. 
  The 
  shale 
  appears 
  hardened 
  and 
  

   baked 
  in 
  the 
  immediate 
  neighborhood 
  and 
  narrow 
  tongues 
  of 
  Mon- 
  

   terey 
  shale, 
  certainly 
  altered 
  along 
  the 
  contact, 
  extend 
  into 
  the 
  mass 
  

   on 
  Tepusquet 
  Creek. 
  Along 
  its 
  edges 
  appear 
  patches 
  of 
  Aucella- 
  

   bearing 
  sandstone 
  belonging 
  to 
  the 
  Knoxville, 
  which 
  were 
  probably 
  

   brought 
  up 
  from 
  below 
  by 
  the 
  intrusion. 
  The 
  diabase 
  in 
  both 
  areas 
  

   is 
  of 
  dark-green 
  color 
  and 
  coarse 
  texture 
  and 
  exhibits 
  sheared 
  ser- 
  

   pentinous 
  facies. 
  

  

  