﻿396 
  H. 
  S. 
  Williams 
  — 
  Southern 
  Devonian 
  formations. 
  

  

  materials 
  themselves 
  ; 
  i. 
  e. 
  limestone, 
  carbonaceous 
  and 
  phos- 
  

   phatic 
  materials 
  are 
  of 
  organic 
  origin, 
  while 
  clastic 
  sediments 
  

   are 
  derived 
  from 
  the 
  decay, 
  fracture 
  and 
  grinding 
  up 
  of 
  pre- 
  

   existing, 
  generally, 
  crystalline 
  and, 
  therefore 
  chiefly, 
  Archaean 
  

   rocks. 
  (2) 
  The 
  differences 
  in 
  size 
  or 
  fineness 
  of 
  grain 
  of 
  the 
  

   materials 
  of 
  clastic 
  rocks 
  may 
  be 
  accounted 
  for 
  by 
  the 
  sorting 
  

   action 
  of 
  moving 
  waters 
  ; 
  and 
  thus 
  all 
  the 
  varieties 
  of 
  rocks 
  

   are 
  brought 
  into 
  a 
  general 
  relationship 
  to 
  the 
  distance 
  from 
  the 
  

   shore-line 
  oh* 
  which 
  they 
  were 
  finally 
  deposited. 
  By 
  the 
  appli- 
  

   cation 
  of 
  these 
  general 
  principles 
  it 
  was 
  found 
  possible 
  to 
  

   interpret 
  the 
  geographical 
  changes 
  in 
  the 
  stratigraphy 
  of 
  the 
  

   formations 
  across 
  New 
  York 
  state, 
  northern 
  Pennsylvania 
  and 
  

   Ohio 
  in 
  terms 
  of 
  distance 
  from 
  the 
  shore 
  line 
  and 
  of 
  oscillations 
  

   of 
  that 
  line 
  backward 
  and 
  forward 
  with 
  general 
  vertical 
  move- 
  

   ments 
  of 
  the 
  crust. 
  By 
  these 
  principles 
  the 
  Catskill 
  was 
  

   shown 
  to 
  be, 
  not 
  a 
  definite 
  chronological 
  formation 
  representing 
  

   the 
  time 
  following 
  the 
  period 
  of 
  the 
  Chemung 
  fauna, 
  but 
  an 
  

   along-shore 
  facies 
  of 
  the 
  Devonian 
  deposits 
  of 
  the 
  northeastern 
  

   bay 
  of 
  this 
  interior 
  sea 
  incident 
  to 
  a 
  gradual 
  rising 
  of 
  the 
  lands 
  

   at 
  that 
  part 
  of 
  the 
  region. 
  The 
  sediments 
  of 
  Catskill 
  facies, 
  

   therefore, 
  occurred 
  as 
  early 
  as 
  the 
  Hamilton 
  in 
  eastern 
  New 
  York, 
  

   while 
  they 
  did 
  not 
  occupy 
  the 
  area 
  of 
  western 
  New 
  York 
  till 
  

   after 
  the 
  end 
  of 
  the 
  Chemung 
  period.* 
  

  

  The 
  entrance 
  of 
  the 
  Cuboides 
  fauna 
  into 
  the 
  New 
  York 
  area 
  

   east 
  of 
  the 
  Cincinnati 
  plateau 
  was 
  also 
  thus 
  found 
  to 
  be 
  coinci- 
  

   dent 
  with 
  the 
  changes 
  of 
  level 
  which 
  were 
  recorded 
  in 
  central- 
  

   western 
  New 
  York 
  and 
  Pennsylvania, 
  by 
  the 
  presence 
  of 
  a 
  

   local 
  limestone 
  of 
  the 
  Tully 
  epoch 
  ; 
  this 
  depression 
  giving 
  

   access 
  to 
  the 
  faunas 
  which 
  had 
  already, 
  in 
  Hamilton 
  time, 
  

   reached 
  as 
  far 
  south 
  as 
  Iowa 
  from 
  the 
  Dakota 
  channel 
  at 
  the 
  

   north. 
  f 
  While 
  the 
  two 
  general 
  principles 
  named 
  were 
  suffi- 
  

   cient 
  to 
  account 
  for 
  these 
  and 
  other 
  differences, 
  I 
  have 
  been 
  

   unable 
  by 
  any 
  combination 
  or 
  commutation 
  of 
  these 
  alone 
  to 
  

   arrive 
  at 
  a 
  satisfactory 
  explanation 
  of 
  the 
  Black 
  shales, 
  so 
  con- 
  

   spicuous 
  to 
  the 
  south, 
  or 
  of 
  the 
  Oriskany 
  whose 
  center 
  of 
  dis- 
  

   tribution 
  seems 
  to 
  be 
  far 
  up 
  in 
  the 
  northeast 
  corner 
  of 
  the 
  sea. 
  

  

  On 
  the 
  supposition 
  that 
  the 
  black 
  shales 
  were 
  clastic 
  sedi- 
  

   ments, 
  derived 
  from 
  the 
  same 
  sources 
  with 
  the 
  other 
  clastic 
  

   sediments 
  of 
  the 
  Devonian 
  system, 
  they 
  should 
  appear 
  in 
  the 
  

   sections, 
  all 
  around 
  the 
  shores 
  of 
  Lauren 
  tia 
  and 
  Appalachia, 
  

   wherever 
  the 
  corresponding 
  fineness 
  of 
  division 
  was 
  reached 
  ; 
  

   but 
  this 
  does 
  not 
  agree 
  with 
  the 
  facts, 
  for 
  in 
  the 
  southern 
  sec- 
  

   tions 
  black 
  shale 
  sedimentation 
  prevails 
  throughout 
  the 
  whole 
  

  

  * 
  Dual 
  nomenclature 
  in 
  geological 
  classification. 
  Jour. 
  Geol., 
  vol. 
  ii. 
  pp. 
  145- 
  

   160, 
  1894. 
  

  

  f 
  The 
  Cuboides 
  zone 
  and 
  its 
  fauna, 
  Geol. 
  Soc. 
  Am. 
  Bull, 
  vol. 
  i, 
  pp. 
  481-500. 
  

   The 
  scope 
  of 
  Paleontology 
  and 
  its 
  value 
  to 
  geologists, 
  Proc. 
  A. 
  A. 
  A. 
  S., 
  vol. 
  

   xli, 
  pp. 
  149-170, 
  1893. 
  

  

  