﻿370 
  A. 
  M. 
  Edwards 
  — 
  Infusorial 
  Earths 
  of 
  Pacific 
  Coast. 
  

  

  to 
  go 
  very 
  fully 
  into 
  the 
  subject 
  of 
  the 
  evident 
  mode 
  of 
  forma- 
  

   tion 
  of 
  the 
  strata 
  containing 
  the 
  microscopic 
  organisms. 
  Since 
  

   that 
  time 
  the 
  Geological 
  Survey 
  of 
  the 
  State 
  of 
  California 
  has 
  

   been 
  undertaken 
  and 
  a 
  much 
  more 
  extended 
  suite 
  of 
  gather- 
  

   ings 
  has 
  come 
  into 
  my 
  hands. 
  

  

  Through 
  the 
  knowledge 
  acquired 
  from 
  the 
  examination 
  of 
  

   these 
  collections 
  made 
  at 
  various 
  points 
  from 
  Puget 
  Sound 
  to 
  

   the 
  southernmost 
  border 
  of 
  California, 
  I 
  have 
  been 
  enabled 
  to 
  

   furnish 
  such 
  information 
  that 
  the 
  history 
  of 
  both 
  the 
  marine 
  and 
  

   fresh 
  water, 
  so 
  called, 
  Infusorial 
  deposits 
  of 
  that 
  portion 
  of 
  the 
  

   country 
  has 
  been 
  pretty 
  thoroughly 
  worked 
  out. 
  With 
  regard 
  

   to 
  the 
  marine 
  strata 
  very 
  little 
  has, 
  as 
  yet, 
  been 
  published. 
  

   The 
  results 
  arrived 
  at 
  concerning 
  one 
  class 
  of 
  the 
  fresh 
  water 
  

   strata 
  has 
  been 
  made 
  known 
  in 
  a 
  communication 
  of 
  Professor 
  

   Whitney's 
  read 
  before 
  the 
  California 
  Academy 
  of 
  ^Natural 
  

   Sciences, 
  February 
  4th, 
  1867. 
  (Proc. 
  Cal. 
  Academy, 
  vol. 
  iii, 
  

   p. 
  319.) 
  These 
  he 
  has 
  therein 
  shown 
  to 
  be 
  the 
  beds 
  of 
  enor- 
  

   mous 
  extinct 
  lakes 
  or 
  inland 
  seas, 
  the 
  material 
  of 
  which 
  has 
  

   been 
  altered 
  in 
  character 
  by 
  the 
  superposition 
  upon 
  it 
  at 
  differ- 
  

   ent 
  periods 
  of 
  lava 
  or 
  sand 
  and 
  gravel 
  or 
  ashes 
  and 
  pumice. 
  

   In 
  this 
  way 
  it 
  can 
  be 
  readily 
  understood 
  that, 
  as 
  the 
  volcanic 
  

   action 
  ceases, 
  a 
  new 
  T 
  growth 
  of 
  microscopic 
  organisms 
  might 
  

   take 
  place 
  over 
  the 
  erupted 
  material 
  lying 
  upon 
  the 
  older 
  

   deposits 
  and, 
  in 
  fact, 
  that 
  many 
  such 
  layers 
  might 
  accumulate 
  

   one 
  over 
  the 
  other. 
  Such 
  has 
  been 
  the 
  case 
  at 
  various 
  points 
  

   upon 
  the 
  Pacific 
  Coast 
  from 
  Puget 
  Sound 
  to 
  Lake 
  Mono 
  in 
  

   Eastern 
  California, 
  which 
  is 
  the 
  most 
  southern 
  point 
  from 
  

   which 
  I 
  have 
  received 
  such 
  material. 
  At 
  some 
  future 
  time 
  I 
  

   may 
  have 
  more 
  to 
  say 
  with 
  regard 
  to 
  this 
  class 
  of 
  deposits, 
  for 
  

   I 
  have 
  examined 
  many 
  of 
  them 
  during 
  the 
  progress 
  of 
  the 
  

   Geological 
  Survey 
  of 
  California 
  and, 
  when 
  my 
  report 
  thereon 
  

   is 
  published, 
  I 
  shall 
  be 
  enabled 
  to 
  go 
  more 
  fully 
  into 
  the 
  sub- 
  

   ject. 
  As 
  I 
  have 
  several 
  specimens 
  from 
  strata 
  of 
  this 
  charac- 
  

   ter 
  to 
  describe 
  in 
  the 
  present 
  report 
  I 
  shall, 
  for 
  the 
  time 
  

   being, 
  indicate 
  them 
  as 
  sub-Plutonic, 
  which 
  is 
  the 
  most 
  distinc- 
  

   tive 
  appellation 
  I 
  can 
  now 
  find 
  for 
  them. 
  

  

  Among 
  the 
  specimens 
  which 
  I 
  have 
  examined 
  in 
  connection 
  

   with 
  this 
  survey, 
  and 
  aside 
  from 
  those 
  which 
  do 
  not 
  contain 
  

   any 
  organic 
  remains, 
  and 
  hence 
  will 
  be 
  treated 
  of 
  separately, 
  I 
  

   have 
  then, 
  first, 
  the 
  sub-Plutonic, 
  which 
  I 
  have 
  just 
  alluded 
  to, 
  

   and 
  which 
  are 
  always 
  of 
  fresh 
  water 
  origin 
  ; 
  second, 
  the 
  fresh 
  

   water 
  deposits 
  of 
  more 
  recent 
  formation 
  and, 
  in 
  fact, 
  which 
  

   are 
  now 
  under 
  process 
  of 
  growth 
  all 
  over 
  the 
  world 
  beneath 
  

   ponds 
  and 
  lakes, 
  and 
  which 
  I 
  have 
  hitherto 
  been 
  in 
  the 
  habit 
  

   of 
  calling 
  sub- 
  Peat, 
  but 
  I 
  have 
  lately 
  preferred 
  to 
  designate 
  as 
  

   Lacustrine 
  Sedimentary, 
  as 
  I 
  consider 
  that 
  they 
  are 
  better 
  so 
  

   indicated. 
  Besides 
  these 
  two 
  classes 
  of 
  deposits, 
  which 
  differ 
  

  

  