﻿218 
  J. 
  J. 
  Stevenson 
  — 
  Origin 
  of 
  Formkohle. 
  

  

  the 
  continuity 
  is 
  as 
  positive 
  as 
  that 
  in 
  a 
  vari-colored 
  sheet 
  of 
  

   paper. 
  The 
  coal 
  throughout 
  shows 
  little 
  more 
  than 
  ordinary 
  

   differences 
  in 
  composition, 
  except 
  that 
  the 
  moisture 
  of 
  Form- 
  

   kohle 
  is 
  apt 
  to 
  be 
  greater 
  owing 
  to 
  the 
  greater 
  porosity 
  ; 
  the 
  

   only 
  positive 
  distinction 
  is 
  in 
  degree 
  of 
  coherence. 
  The 
  pro- 
  

   files 
  by 
  Raefier 
  and 
  the 
  earlier 
  observations 
  by 
  Stohr 
  and 
  Russ- 
  

   wurra* 
  confirm 
  these 
  statements. 
  

  

  When 
  one 
  considers 
  the 
  hypothesis 
  of 
  origin 
  by 
  transport, 
  

   he 
  finds 
  serious 
  difficulties 
  at 
  once. 
  Allusion 
  has 
  been 
  made 
  to 
  

   relations 
  of 
  the 
  types 
  in 
  a 
  single 
  bench 
  ; 
  but 
  a 
  more 
  perplexing 
  

   condition 
  is 
  the 
  immense 
  mass 
  of 
  the 
  material 
  ; 
  Davisf 
  gives 
  

   a 
  measurement 
  of 
  328 
  feet 
  near 
  Cologne 
  ; 
  PlettnerJ 
  has 
  shown 
  

   the 
  great 
  abundance 
  of 
  Formkohle 
  in 
  parts 
  of 
  Brandenburg, 
  

   while 
  Raefler, 
  Russwurm, 
  Stohr, 
  Lasoevres 
  and 
  others 
  have 
  

   made 
  certain 
  its 
  prevalence 
  in 
  much 
  of 
  Sachsen 
  and 
  the 
  adjoin- 
  

   ing 
  region 
  ; 
  v. 
  Ammon§ 
  found 
  it 
  the 
  prevailing 
  type 
  in 
  south- 
  

   ern 
  Bavaria 
  ; 
  and 
  closely 
  allied 
  coal 
  is 
  present 
  in 
  much 
  of 
  the 
  

   Texas 
  region. 
  The 
  physical 
  character 
  varies; 
  sometimes 
  the 
  

   mass 
  is 
  a 
  confused 
  intermingling 
  of 
  large 
  and 
  small 
  pieces 
  in 
  a 
  

   matrix 
  of 
  incoherent, 
  more 
  or 
  less 
  dustlike 
  or 
  crumblike 
  coal 
  ; 
  

   but 
  at 
  others, 
  as 
  at 
  Yoss 
  according 
  to 
  Potonie, 
  coarse 
  frag- 
  

   ments 
  are 
  absent. 
  Stems 
  of 
  trees, 
  occasionally 
  very 
  large 
  and 
  

   often 
  very 
  numerous, 
  are 
  found 
  in 
  the 
  Formkohle. 
  The 
  

   Knorpel- 
  and 
  the 
  Formkohle 
  of 
  a 
  given 
  bed 
  or 
  bench 
  are 
  of 
  the 
  

   same 
  age 
  throughout, 
  Oligocene 
  or 
  Eocene 
  as 
  the 
  case 
  may 
  be, 
  

   for 
  the 
  plant 
  remains 
  are 
  the 
  same 
  in 
  both. 
  The 
  important 
  

   deposits 
  of 
  Sachsen, 
  Brandenburg 
  and 
  the 
  Cologne 
  region 
  are 
  

   Oligocene 
  and 
  there 
  is 
  no 
  Eocene 
  coal 
  in 
  those 
  areas. 
  The 
  

   brown 
  coal 
  basins 
  are 
  small 
  and 
  many 
  of 
  them 
  appear 
  to 
  have 
  

   been 
  wholly 
  independent 
  from 
  their 
  beginning. 
  

  

  The 
  hypothesis 
  of 
  secondarily-allochthonous 
  origin 
  appears 
  

   to 
  require 
  as 
  a 
  basal 
  postulate 
  that 
  the 
  coal 
  had 
  become 
  hard 
  

   prior 
  to 
  removal. 
  One 
  is 
  told 
  that 
  the 
  large 
  fragments 
  are 
  all 
  

   angular, 
  as 
  they 
  ought 
  to 
  be, 
  because 
  rounded 
  pebbles 
  are 
  not 
  to 
  

   be 
  expected, 
  for 
  coal 
  is 
  brittle. 
  But 
  the 
  cutting 
  and 
  transpor- 
  

   tation 
  must 
  have 
  been 
  done 
  while 
  the 
  Knorpelkohle 
  was 
  still 
  

   exposed,' 
  for 
  the 
  statement 
  is 
  made 
  that 
  channels 
  in 
  the 
  coal 
  

   bed 
  were 
  filled 
  with 
  transported 
  coal. 
  This 
  certainly 
  involves 
  

   the 
  conception 
  that 
  the 
  coal 
  was 
  already 
  hard 
  before 
  it 
  had 
  

   received 
  a 
  cover 
  of 
  inorganic 
  material, 
  since 
  there 
  is 
  no 
  coal 
  of 
  

   earlier 
  age 
  in 
  the 
  districts. 
  The 
  question 
  respecting 
  the 
  time 
  

  

  *E. 
  Stohr, 
  " 
  Das 
  Pyropissit 
  Vorkommen 
  in 
  den 
  Braunkohle 
  bei 
  Weissen- 
  

   fels 
  und 
  Zeitz." 
  Neues 
  Jahrb., 
  Jahrg. 
  1867, 
  pp. 
  407-409 
  : 
  P. 
  Russwurm, 
  

   Zeitschr. 
  f. 
  prakt. 
  Geologie, 
  Jahrg. 
  17, 
  1909. 
  pp. 
  93. 
  94. 
  

  

  fC. 
  A. 
  Davis, 
  U. 
  S. 
  Bureau 
  of 
  Mines, 
  Tecbn. 
  Paper 
  55, 
  1913, 
  pp. 
  5, 
  6. 
  

  

  JPlettner, 
  Zeitschr. 
  d, 
  d. 
  geol. 
  Gesfill., 
  IV 
  Band. 
  1852, 
  pp. 
  249-483. 
  

  

  § 
  L. 
  v. 
  Amnion, 
  " 
  Baverische 
  Braunkohlen 
  und 
  ihre 
  Verwertung," 
  Miin- 
  

   chen, 
  1911. 
  

  

  