﻿440 
  J. 
  Barrett 
  — 
  Upper 
  Devonian 
  Delta 
  of 
  the 
  

  

  accumulation.* 
  They 
  may 
  of 
  course 
  be 
  of 
  terrestrial 
  origin 
  

   also 
  when 
  thinner 
  and 
  more 
  limited, 
  but 
  in 
  that 
  case 
  so 
  far 
  as 
  

   these 
  characters 
  determine 
  they 
  may 
  also 
  be 
  marine. 
  

  

  The 
  criteria 
  previously 
  discussed 
  seem 
  definitive. 
  There 
  

   are 
  other 
  features, 
  however, 
  which 
  may 
  be 
  regarded 
  as 
  supple- 
  

   mental 
  criteria. 
  For 
  example, 
  river 
  sands 
  are 
  deposited 
  from 
  

   flowing 
  waters 
  and 
  are 
  more 
  cross-bedded, 
  heterogeneous 
  and 
  

   current-marked. 
  Marine 
  sands 
  are 
  mostly 
  spread 
  by 
  the 
  oscil- 
  

   lations 
  of 
  waves. 
  They 
  tend 
  to 
  be 
  evenly 
  bedded, 
  more 
  cleanly 
  

   sorted, 
  ripple-marked, 
  and 
  often 
  exhibit 
  a 
  flagstone 
  character. 
  

   But 
  neither 
  kind 
  of 
  action 
  is 
  restricted 
  wholly 
  to 
  either 
  the 
  

   land 
  or 
  sea; 
  since 
  shallow 
  seas 
  may 
  be 
  swept 
  with 
  storm-driven 
  

   currents 
  and 
  marked 
  by 
  shifting 
  bars, 
  and 
  broad 
  river 
  plains 
  

   when 
  overspread 
  with 
  seasonal 
  floods 
  simulate, 
  for 
  the 
  time, 
  

   permanent 
  bodies 
  of 
  water. 
  It 
  should 
  be 
  noted 
  here, 
  however, 
  

   that 
  if 
  the 
  terrestrial 
  origin 
  of 
  the 
  Catskill 
  formation 
  be 
  

   accepted 
  on 
  the 
  basis 
  of 
  the 
  other 
  criteria, 
  as 
  discussed 
  in 
  the 
  

   following 
  pages, 
  it 
  tends 
  to 
  show 
  pervasive 
  cross 
  bedding 
  to 
  

   be 
  a 
  criterion 
  of 
  considerable 
  supplemental 
  value 
  ; 
  for 
  the 
  

   argillaceous 
  sandstones 
  of 
  the 
  Catskill 
  reveal 
  on 
  weathering 
  a 
  

   very 
  characteristic 
  oblique 
  bedding 
  which 
  the 
  evenly 
  bedded 
  

   Chemung 
  sandstones, 
  representing 
  the 
  synchronous 
  marine 
  

   deposits, 
  fail 
  to 
  show. 
  

  

  Distribution 
  and 
  Character 
  of 
  the 
  Significant 
  Formations. 
  

   Purpose 
  of 
  the 
  Descriptions. 
  

  

  The 
  fundamental 
  requirement 
  in 
  scientific 
  method 
  is 
  the 
  

   separation 
  of 
  facts, 
  principles, 
  hypotheses, 
  and 
  inferences. 
  In 
  

   the 
  problem 
  in 
  question 
  there 
  is 
  a 
  large 
  groundwork 
  of 
  well- 
  

   determined 
  information 
  and 
  a 
  presentation 
  of 
  this 
  is 
  needed 
  as 
  

   a 
  basis 
  for 
  further 
  discussion. 
  The 
  conclusions 
  to 
  which 
  these 
  

   facts 
  seem 
  to 
  lead 
  have 
  been 
  stated. 
  Consequently 
  their 
  sig- 
  

   nificance 
  will 
  appear 
  as 
  they 
  are 
  presented. 
  To 
  some 
  extent 
  

   the 
  descriptions 
  furnish 
  the 
  basis 
  for 
  drawing 
  conclusions, 
  but 
  

   to 
  an 
  even 
  larger 
  extent, 
  if 
  the 
  conclusions 
  be 
  accepted, 
  the 
  

   facts 
  show 
  what 
  are 
  the 
  accessory 
  characteristics 
  of 
  subaerial 
  

   and 
  subaqueous 
  delta 
  beds, 
  developed 
  under 
  certain 
  physio- 
  

   graphic 
  and 
  climatic 
  conditions. 
  

  

  The 
  delta 
  conditions 
  make 
  themselves 
  evident 
  near 
  the 
  

   beginning 
  of 
  the 
  Upper 
  Devonian, 
  and 
  the 
  formations, 
  which 
  

   when 
  pieced 
  together 
  make 
  the 
  ancient 
  delta, 
  are 
  as 
  follows 
  : 
  

   The 
  Oneonta 
  formation 
  consists 
  of 
  the 
  early 
  terrestrial 
  deposits 
  

   of 
  eastern 
  JSfew 
  York, 
  the 
  Portage 
  beds 
  being 
  the 
  correspond- 
  

   ing 
  marine 
  equivalents 
  ; 
  above 
  these 
  come 
  the 
  Catskill 
  on 
  the 
  

  

  * 
  Joseph 
  Barrell. 
  Some 
  distinctions 
  between 
  marine 
  and 
  terrestrial 
  con- 
  

   glomerates. 
  Abstract, 
  Geol. 
  Soc. 
  Am.,. 
  Bull., 
  xx, 
  p. 
  620, 
  1908. 
  

  

  