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  Scientific 
  Intelligence. 
  

  

  out 
  superfluous 
  names 
  and 
  select 
  our 
  comprehensive 
  terms, 
  such 
  

   as 
  would 
  embrace 
  all 
  the 
  elastics 
  of 
  any 
  part 
  of 
  the 
  Archean, 
  after 
  

   a 
  few 
  move 
  final 
  reports 
  have 
  been 
  written. 
  When 
  the 
  history 
  

   of 
  the 
  Archean 
  has 
  been 
  worked 
  out 
  as 
  fully 
  as 
  may 
  be, 
  the 
  names 
  

   of 
  all 
  the 
  clastic 
  formations 
  comprised 
  in 
  it 
  will 
  be 
  too 
  numerous 
  

   to 
  refer 
  to 
  except 
  by 
  comprehensive 
  designations 
  and 
  groupings, 
  

   but 
  to 
  say 
  that 
  " 
  under 
  the 
  term 
  Keewatin 
  are 
  included 
  all 
  the 
  

   elastics 
  of 
  the 
  Archean 
  " 
  is 
  simply 
  to 
  set 
  up 
  Keewatin 
  as 
  a 
  

   synonym 
  for 
  Archean, 
  which 
  of 
  course 
  is 
  not 
  Mr. 
  Winchell's 
  

   intention. 
  

  

  Another 
  point 
  of 
  prime 
  importance 
  for 
  Archean 
  geology 
  is 
  the 
  

   segregation 
  of 
  the 
  upper 
  from 
  the 
  lower 
  Keewatin, 
  by 
  the 
  recog- 
  

   nition 
  of 
  the 
  significance 
  of 
  the 
  conglomerate 
  at 
  the 
  base 
  of 
  the 
  

   upper 
  series. 
  The 
  true 
  position 
  of 
  this 
  conglomerate 
  as 
  marking 
  

   an 
  unconformity 
  within 
  the 
  Archean 
  was 
  pointed 
  out 
  by 
  the 
  writer 
  

   several 
  years 
  ago 
  and 
  the 
  work 
  of 
  the 
  Minnesota 
  Survey 
  sustains 
  

   this 
  view. 
  Upper 
  and 
  lower 
  Keewatin 
  certainly 
  both 
  antedate 
  

   the 
  great 
  hiatus 
  which 
  separates 
  the 
  Archean 
  from 
  the 
  Animikie. 
  

   In 
  this 
  two-fold 
  subdivision 
  of 
  the 
  Keewatin 
  we 
  very 
  probably 
  

   have 
  the 
  correlatives 
  of 
  the 
  upper 
  and 
  lower 
  Huronian 
  of 
  Lake 
  

   Huron, 
  especially 
  in 
  the 
  light 
  of 
  Coleman's 
  more 
  recent 
  observa- 
  

   tions. 
  This 
  correlation 
  if 
  well 
  founded 
  would 
  greatly 
  simplify 
  

   the 
  present 
  tangled 
  condition 
  of 
  Lake 
  Superior 
  geology. 
  If 
  

   the 
  upper 
  Keewatin 
  be 
  the 
  correlative 
  of 
  the 
  upper 
  Huronian, 
  

   as 
  seems 
  to 
  the 
  writer 
  extremely 
  probable, 
  we 
  must 
  relegate 
  to 
  

   limbo 
  that 
  far-fetched 
  correlation 
  of 
  the 
  Animikie 
  and 
  upper 
  

   Huronian, 
  which 
  has 
  become 
  intrenched, 
  as 
  only 
  error 
  can, 
  in 
  the 
  

   literature 
  of 
  pre-Cambrian 
  geology 
  of 
  the 
  past 
  decade. 
  It 
  is 
  this 
  

   supposed 
  equivalence 
  of 
  the 
  Animikie 
  and 
  upper 
  Huronian 
  which 
  

   has 
  led 
  to 
  the 
  remarkable 
  attempt 
  to 
  pull 
  the 
  Huronian 
  out 
  of 
  the 
  

   Archean 
  and 
  make 
  it 
  a 
  subdivision 
  ol 
  the 
  Algonkian. 
  This 
  idea 
  

   once 
  happily 
  demolished 
  it 
  is 
  to 
  be 
  hoped 
  that 
  the 
  Algonkian 
  will 
  

   fall 
  into 
  its 
  proper 
  place 
  in 
  taxonomy 
  as 
  a 
  designation 
  for 
  an 
  

   assemblage 
  of 
  rocks 
  between 
  the 
  Archean 
  and 
  the 
  Cambrian, 
  and 
  

   that 
  it 
  will 
  no 
  longer 
  like 
  Pharaoh's 
  lean 
  kine 
  attempt 
  to 
  fatten 
  

   itself 
  by 
  devouring 
  the 
  plump 
  and 
  well-favored 
  formations 
  of 
  the 
  

   Archean. 
  

  

  Upon 
  the 
  worn 
  surface 
  of 
  this 
  Archean 
  complex 
  rests 
  the 
  

   Animikie 
  in 
  little 
  disturbed 
  attitudes, 
  a 
  purely 
  clastic 
  series, 
  near 
  

   the 
  base 
  of 
  which 
  occur 
  the 
  ore 
  bodies 
  of 
  the 
  now 
  famous 
  Mesabi 
  

   iron 
  range, 
  the 
  origin 
  of 
  which 
  has 
  been 
  so 
  ably 
  discussed 
  by 
  

   Spun* 
  in 
  an 
  earlier 
  publication 
  of 
  the 
  Survey. 
  The 
  Animikie 
  

   embraces 
  the 
  following 
  four 
  subdivisions 
  in 
  ascending 
  order: 
  

   1. 
  Quartzite 
  formation. 
  2. 
  Taconite 
  or 
  iron-bearing 
  formation, 
  

   varying 
  in 
  character 
  from 
  hematite 
  to 
  a 
  rock 
  which 
  has 
  been 
  

   identified 
  as 
  an 
  altered 
  greensand. 
  3. 
  Black 
  slate 
  formation. 
  

   4. 
  Graywacke 
  slate 
  formation. 
  The 
  trap 
  sheets 
  so 
  common 
  in 
  

   the 
  Animikie 
  as 
  intercalations 
  in 
  the 
  formations 
  above 
  enumer- 
  

   ated, 
  which 
  a 
  few 
  years 
  ago 
  were 
  commonly 
  supposed 
  to 
  be 
  con- 
  

   temporaneous 
  lava 
  flows, 
  are 
  recognized 
  in 
  their 
  true 
  character 
  as 
  

   intrusive 
  sills. 
  The 
  faulting 
  which 
  characterizes 
  the 
  Animikie 
  in 
  

  

  