﻿ACADEMY 
  OF 
  SCIENCES. 
  385 
  

  

  From 
  these 
  one 
  might 
  suppose 
  that 
  California 
  would 
  soon 
  eclipse 
  all 
  other 
  parts 
  

   of 
  the 
  world 
  in 
  coal 
  production, 
  but 
  the 
  fact 
  is, 
  that 
  in 
  ninety-nine 
  cases 
  out 
  of 
  one 
  

   hundred 
  these 
  discoveries 
  are 
  of 
  no 
  value 
  whatever. 
  He 
  had 
  examined 
  such 
  

   coal 
  strata 
  in 
  over 
  one 
  hundred 
  locai^ties 
  between 
  San 
  Francisco 
  and 
  San 
  

   Dieg'O, 
  besides 
  some 
  in 
  Sonoma 
  and 
  Marin 
  Counties. 
  

  

  Although 
  the 
  unscientific 
  sneer 
  at 
  geological 
  facts 
  and 
  fossils 
  as 
  not 
  practi- 
  

   cally 
  useful, 
  they 
  are 
  really 
  the 
  only 
  reliable 
  guides 
  in 
  determining 
  the 
  age 
  and 
  

   pi'obable 
  value 
  of 
  coal 
  deposits. 
  The 
  true 
  coal 
  of 
  the 
  carboniferous 
  rock 
  in 
  

   other 
  countries 
  was 
  formed 
  from 
  the 
  tree-ferns, 
  algie, 
  and 
  other 
  plants 
  of 
  low 
  

   organization. 
  

  

  None 
  such 
  had 
  been 
  found 
  on 
  this 
  Coast, 
  and 
  from 
  the 
  fact 
  that 
  ours 
  con- 
  

   tained 
  remains 
  of 
  coniferous 
  and 
  dicotyledonous 
  trees, 
  geologists 
  had 
  long 
  con- 
  

   sidered 
  it 
  all 
  as 
  lignite 
  ; 
  but 
  practically 
  that 
  of 
  Yancouver 
  Island, 
  Bellingham 
  

   Bay, 
  Coos 
  Bay, 
  and 
  Mount 
  Diablo 
  was 
  as 
  good 
  as 
  much 
  of 
  the 
  older 
  coal. 
  

   The 
  most 
  northern 
  localities 
  mentioned 
  had 
  been 
  determined 
  beyond 
  doubt 
  by 
  

   the 
  fossils 
  as 
  of 
  cretaceous 
  age, 
  but 
  there 
  is 
  still 
  some 
  doubt 
  as 
  to 
  those 
  of 
  

   California, 
  which 
  may 
  be 
  partly 
  or 
  entirely 
  above 
  the 
  cretaceous 
  strata, 
  like 
  the 
  

   Rocky 
  Mountain 
  coal, 
  which 
  is 
  generally 
  considered 
  eocene. 
  

  

  This, 
  however, 
  does 
  not 
  affect 
  the 
  value 
  of 
  fossil 
  evidence, 
  as 
  the 
  species 
  of 
  

   both 
  these 
  formations 
  are 
  mostry 
  extinct, 
  and 
  any 
  coal 
  found 
  associated 
  with 
  

   fossils 
  of 
  living 
  species 
  must 
  be 
  of 
  later 
  date. 
  No 
  paying 
  beds 
  of 
  coal 
  have 
  

   been 
  found 
  anywhere 
  of 
  later 
  date 
  than 
  these. 
  

  

  It 
  does 
  not 
  follow, 
  however, 
  that 
  because 
  a 
  stratum 
  is 
  cretaceous, 
  it 
  will 
  pay. 
  

   Numerous 
  strata 
  in 
  that 
  formation 
  in 
  the 
  Coast 
  Range 
  are 
  too 
  thin 
  to 
  pay, 
  

   though 
  of 
  pretty 
  good 
  quality. 
  None 
  will 
  pay 
  if 
  less 
  than 
  two 
  feet 
  thick, 
  and 
  

   in 
  most 
  places 
  a 
  thickness 
  of 
  four 
  feet 
  is 
  necessary, 
  if 
  the 
  coal 
  is 
  no 
  better, 
  nor 
  

   more 
  accessible, 
  than 
  that 
  of 
  Mount 
  Diablo. 
  Much 
  of 
  the 
  cretaceous 
  strata 
  is 
  

   also 
  so 
  metamorphosed 
  that 
  the 
  coal 
  has 
  been 
  ruined 
  by 
  infiltration 
  of 
  iron 
  and 
  

   silica, 
  with 
  other 
  minerals, 
  the 
  surrounding 
  sandstones 
  being 
  converted 
  into 
  

   jasper 
  or 
  serpentine. 
  

  

  The 
  fossil 
  shells 
  found 
  in 
  connection 
  with 
  this 
  coal 
  show 
  that 
  it 
  was 
  formed 
  

   by 
  accumulation 
  of 
  trees, 
  etc., 
  in 
  shallow 
  bays, 
  at 
  the 
  mouths 
  of 
  rivers 
  in 
  fresh 
  

   or 
  brackish 
  water, 
  and 
  therefore 
  along 
  the 
  shores 
  of 
  older 
  continents 
  or 
  large 
  

   islands. 
  Often 
  these 
  deposits 
  have 
  been 
  sunk 
  afterwards, 
  and 
  strata 
  with 
  

   marine 
  shells 
  have 
  accumulated 
  above 
  them 
  to 
  a 
  great 
  depth, 
  when 
  all 
  would 
  be 
  

   again 
  raised 
  above 
  the 
  sea. 
  In 
  the 
  Coast 
  Range 
  cretaceous 
  coal-strata 
  exist, 
  

   above 
  which 
  miocene 
  tertiary 
  strata, 
  full 
  of 
  shells 
  of 
  living 
  kinds, 
  were 
  de- 
  

   posited 
  to 
  a 
  thickness 
  of 
  one 
  thousand 
  feet, 
  but 
  afterwards 
  removed 
  sufficiently 
  

   to 
  show 
  the 
  coal 
  beneath. 
  

  

  The 
  beds 
  of 
  undoubted 
  tertiary 
  age 
  are 
  numerous 
  in 
  the 
  Coast 
  Range, 
  and 
  

   usually 
  show 
  the 
  vegetable 
  structure 
  so 
  plainly 
  as 
  to 
  be 
  recognized 
  as 
  lignites 
  

   by 
  everybody, 
  besides 
  differing* 
  from 
  coal 
  in 
  a 
  more 
  or 
  less 
  brown 
  tint. 
  Some 
  

   lignites 
  may 
  pay 
  for 
  working, 
  for 
  local 
  use 
  especially, 
  as 
  they 
  do 
  in 
  some 
  parts 
  

   of 
  Europe. 
  Nearly 
  all 
  of 
  that 
  in 
  the 
  coast 
  Range 
  is, 
  however, 
  in 
  either 
  too 
  thin 
  

   beds, 
  or 
  too 
  full 
  of 
  sulphur 
  and 
  other 
  impurities. 
  In 
  a 
  few 
  places 
  it 
  has 
  been 
  

   purified 
  and 
  hardened 
  so 
  as 
  to 
  resemble 
  anthracite, 
  apparently 
  by 
  the 
  action 
  of 
  

  

  