﻿220 
  J. 
  J. 
  Stevenson 
  — 
  Origin 
  of 
  Formkohle. 
  

  

  for 
  supposing 
  that 
  pulpy 
  peat, 
  when 
  transferred 
  and 
  kept 
  under 
  

   a 
  water 
  cover, 
  would 
  undergo 
  changes 
  so 
  different 
  from 
  those 
  

   which 
  would 
  have 
  occurred 
  on 
  the 
  original 
  site 
  as 
  to 
  give 
  pul- 
  

   verulent 
  coal 
  instead 
  of 
  solid 
  coal. 
  It' 
  there 
  were 
  no 
  cover 
  of 
  

   water, 
  the 
  saturated 
  peat 
  would 
  dry 
  on 
  the 
  surface, 
  would 
  be 
  

   oxidized 
  and 
  would 
  be 
  blown 
  away. 
  This 
  condition 
  of 
  wasting 
  

   would 
  be 
  the 
  same 
  if 
  the 
  material 
  were 
  a 
  powdery 
  imperfect 
  

   brown 
  coal. 
  

  

  There 
  is 
  little 
  evidence 
  of 
  selection 
  by 
  gravity 
  in 
  deposits 
  of 
  

   Formkohle. 
  Some 
  beds 
  have 
  incoherent 
  coal 
  in 
  the 
  upper 
  

   bench 
  and 
  lump 
  coal 
  in 
  the 
  lower, 
  while 
  in 
  others 
  the 
  positions 
  

   are 
  reversed. 
  Kaefler 
  has 
  shown 
  that 
  passage 
  from 
  one 
  type 
  to 
  

   the 
  other 
  is 
  gradual 
  and 
  within 
  a 
  space 
  so 
  small 
  as 
  to 
  render 
  

   the 
  hypothesis 
  of 
  selection 
  incompetent. 
  Indeed, 
  the 
  relation 
  

   is 
  so 
  indefinite 
  that 
  miners 
  use 
  the 
  terms 
  arbitrarily, 
  coal 
  from 
  

   one 
  mine 
  being 
  called 
  Knorpel-, 
  which 
  in 
  adjacent 
  mines 
  would 
  

   be 
  called 
  Formkohle. 
  The 
  presence 
  of 
  logs 
  in 
  the 
  fine 
  coal 
  is 
  

   evidence 
  that 
  there 
  was 
  little 
  selection, 
  for 
  those 
  are 
  often 
  

   large 
  and 
  very 
  numerous. 
  

  

  Pockets, 
  even 
  layers 
  of 
  sand, 
  gravel 
  and 
  clay 
  are 
  not 
  evi- 
  

   dence 
  that 
  the 
  mass 
  consists 
  of 
  transported 
  matter. 
  Such 
  

   pockets 
  and 
  layers 
  occur 
  in 
  peat 
  deposits 
  generally 
  and 
  one 
  can 
  

   see 
  them 
  on 
  the 
  surface 
  of 
  growing 
  bogs, 
  where 
  their 
  origin 
  is 
  

   evident, 
  and 
  where 
  no 
  one 
  would 
  dream 
  of 
  utilizing 
  them 
  to 
  

   prove 
  that 
  the 
  peat 
  is 
  allochthonous. 
  

  

  The 
  distribution 
  of 
  pyropissite 
  and 
  Schwelkohle 
  gives 
  no 
  

   support 
  to 
  the 
  hypothesis. 
  Pyropissite 
  material 
  is 
  supposed 
  to 
  

   have 
  been 
  carried 
  farther 
  than 
  that 
  of 
  the 
  brown 
  coal 
  and 
  to 
  

   have 
  reached 
  the 
  place 
  of 
  deposition 
  at 
  the 
  northwest. 
  Raefler's 
  

   study, 
  not 
  of 
  a 
  single 
  property 
  but 
  of 
  the 
  whole 
  region, 
  has 
  

   shown 
  that 
  the 
  concentration 
  is 
  certainly 
  notable 
  in 
  the 
  north- 
  

   west, 
  but 
  not 
  in 
  such 
  way 
  as 
  required 
  by 
  the 
  hypothesis. 
  The 
  

   richest 
  localities 
  are 
  several 
  small 
  basins, 
  independent 
  and 
  prob- 
  

   ably 
  always 
  so, 
  in 
  which 
  the 
  concentration 
  is 
  along 
  the 
  borders, 
  

   not 
  in 
  the 
  central 
  portion 
  Pyropissite 
  occurs 
  in 
  nests, 
  streaks 
  

   and 
  layers 
  within 
  Knorpelkohle 
  (autochthonous) 
  as 
  it 
  does 
  in 
  

   Formkohle 
  (secondarily-allochthonous). 
  Stohr 
  and 
  Fiebelkorn* 
  

   have 
  shown 
  that 
  the 
  Schwelkohle 
  is 
  confined 
  to 
  no 
  particular 
  

   position 
  in 
  the 
  bed. 
  It 
  is 
  certain 
  that 
  the 
  coaly 
  material 
  must 
  

   have 
  been 
  in 
  advanced 
  stage 
  of 
  conversion 
  so 
  as 
  to 
  make 
  pos- 
  

   sible 
  separation 
  of 
  pyropissite 
  from 
  other 
  substances 
  borne 
  by 
  

   the 
  moving 
  water; 
  but 
  whether 
  the 
  material 
  were 
  well 
  

   advanced 
  or 
  not, 
  one 
  cannot 
  well 
  conceive 
  how 
  the 
  pyropissite 
  

   could 
  be 
  deposited 
  by 
  a 
  current, 
  slow 
  or 
  swift, 
  since 
  its 
  gravity 
  

   is 
  less 
  than 
  that 
  of 
  water. 
  Deposition 
  could 
  come 
  only 
  through 
  

   evaporation. 
  

  

  *M. 
  Fiebelkorn, 
  Zeitschr. 
  f. 
  pr. 
  Geol., 
  Jahrg. 
  1895, 
  pp. 
  360, 
  403, 
  404. 
  

  

  