﻿H. 
  L. 
  Smyth 
  — 
  Geology 
  of 
  Steep 
  Rock 
  Zake, 
  Ont. 
  331 
  

  

  the 
  thickness 
  of 
  the 
  series 
  measured 
  in 
  section 
  has 
  been 
  largely 
  

   but 
  indeterminately 
  increased. 
  In 
  the 
  stretch 
  from 
  the 
  Elbow- 
  

   north 
  to 
  the 
  head 
  of 
  Falls 
  Bay, 
  west 
  of 
  the 
  axial 
  plane, 
  the 
  

   series 
  is 
  much 
  thinner, 
  probably 
  as 
  the 
  result 
  of 
  three 
  causes 
  : 
  

   (1) 
  A 
  general 
  stretching 
  in 
  this 
  direction. 
  (2) 
  A 
  possible 
  

   faulting 
  along 
  the 
  axis. 
  This 
  has 
  not 
  been 
  observed, 
  however. 
  

   (3) 
  A 
  probable 
  thinning 
  out 
  of 
  the 
  trap 
  horizon 
  in 
  going 
  west. 
  

  

  For 
  these 
  reasons 
  a 
  measurement 
  across 
  the 
  series 
  there 
  

   would 
  probably 
  be 
  at 
  least 
  as 
  much 
  less 
  than 
  the 
  true 
  thick- 
  

   ness 
  as 
  the 
  East 
  Bay 
  section 
  is 
  greater. 
  A 
  mean 
  between 
  them, 
  

   or 
  4500 
  feet, 
  may 
  be 
  taken 
  as 
  an 
  approximation 
  to 
  the 
  true 
  

   thickness. 
  

  

  General 
  Considerations. 
  — 
  The 
  study 
  of 
  the 
  Steep 
  Rock 
  

   series 
  shows 
  some 
  results 
  both 
  positive 
  and 
  negative 
  which 
  

   have 
  a 
  general 
  interest 
  in 
  connection 
  w 
  T 
  ith 
  the 
  geology 
  of 
  the 
  

   region 
  Sf.W. 
  of 
  Lake 
  Superior. 
  

  

  1st. 
  The 
  contact 
  of 
  Formation 
  I 
  with 
  the 
  basement 
  complex 
  is 
  

   one 
  of 
  erosion. 
  

  

  2d. 
  The 
  complex 
  at 
  the 
  time 
  of 
  the 
  deposition 
  of 
  the 
  Steep 
  

   Rock 
  series 
  was 
  made 
  up 
  of 
  consolidated 
  crystalline 
  rocks, 
  and 
  

   there 
  is 
  no 
  evidence 
  whatever 
  that 
  it 
  has 
  since 
  undergone 
  

   fusion, 
  or 
  recurred 
  to 
  the 
  condition 
  of 
  a 
  magma. 
  

  

  3d. 
  The 
  rocks 
  of 
  the 
  Steep 
  Rock 
  series 
  have 
  been 
  subjected 
  

   at 
  two 
  periods, 
  more 
  or 
  less 
  distant, 
  from 
  one 
  another, 
  to 
  the 
  

   action 
  of 
  great 
  orotechnic 
  forces, 
  which 
  acted 
  — 
  the 
  first 
  in 
  a 
  

   N.E. 
  and 
  S.W. 
  direction, 
  and 
  the 
  second 
  in 
  a 
  N.W. 
  and 
  S.E. 
  

  

  4th. 
  The 
  latter 
  force 
  has 
  imposed 
  upon 
  all 
  the 
  rocks 
  of 
  the 
  

   region 
  a 
  N.E. 
  structure, 
  which 
  has 
  largely, 
  but 
  not 
  entirely, 
  

   obliterated 
  preexisting 
  lamination 
  in 
  the 
  sediments 
  and 
  schists 
  

   of 
  the 
  Steep 
  Rock 
  series. 
  

  

  5th. 
  The 
  two 
  orotechnic 
  actions 
  have 
  produced 
  great 
  devel- 
  

   opments 
  of 
  autoclastic* 
  schists, 
  both 
  in 
  the 
  granites 
  and 
  in 
  the 
  

   rocks 
  of 
  the 
  Steep 
  Rock 
  series 
  ; 
  the 
  present 
  structure 
  in 
  which 
  

   was 
  induced 
  and 
  determined 
  in 
  direction 
  by 
  the 
  last 
  force. 
  

  

  The 
  consideration 
  of 
  the 
  Aticokan 
  series, 
  with 
  a 
  more 
  

   general 
  discussion 
  of 
  the 
  mutual 
  relations 
  of 
  the 
  three 
  series 
  of 
  

   rocks, 
  and 
  an 
  attempt 
  at 
  correlation, 
  must 
  be 
  deferred 
  to 
  

   another 
  paper. 
  

  

  The 
  author 
  wishes 
  to 
  express 
  his 
  great 
  obligations 
  to 
  Prof. 
  

   Raphael 
  Pumpelly 
  for 
  many 
  valuable 
  suggestions. 
  Mr. 
  C. 
  

   Livy 
  Whittle, 
  of 
  Cambridge, 
  Mass., 
  has 
  kindly 
  examined 
  a 
  

   number 
  of 
  thin 
  sections 
  from 
  the 
  Steep 
  Rock 
  series, 
  and 
  the 
  

   results 
  of 
  his 
  study 
  are 
  incorporated 
  in 
  the 
  above 
  description 
  

   of 
  formations. 
  

  

  Port 
  Arthur, 
  Ontario, 
  June, 
  1891. 
  

  

  * 
  That 
  is, 
  schists 
  formed 
  iD 
  place 
  from 
  massive 
  rocks 
  by 
  crushing 
  and 
  squeez- 
  

   ing, 
  without 
  intervening 
  processes 
  of 
  disintegration 
  or 
  erosion, 
  removal 
  and 
  depo- 
  

   sition. 
  

  

  