﻿H. 
  L. 
  Smyth 
  — 
  Geooogy 
  of 
  Steep 
  Rock 
  Lake, 
  Out. 
  319 
  

  

  From 
  the 
  southern 
  point 
  of 
  Pine 
  Beach 
  the 
  shore 
  again 
  

   follows 
  the 
  strike 
  of 
  the 
  rocks, 
  as 
  it 
  sweeps 
  round 
  the 
  south 
  

   pitching 
  axis 
  of 
  the 
  middle 
  anticlinal 
  ; 
  and 
  in 
  the 
  stretch 
  from 
  

   Bowlder 
  Point 
  to 
  the 
  Upper 
  Narrows, 
  in 
  which 
  the 
  strike 
  

   locally 
  varies 
  between 
  N. 
  2° 
  W. 
  and 
  N. 
  18° 
  E. 
  the 
  water 
  line 
  

   minutely 
  corresponds 
  to 
  the 
  minor 
  deflections. 
  This 
  shore 
  

   shows 
  continuous 
  rock 
  exposure, 
  and 
  the 
  cliffs 
  reach 
  a 
  height 
  

   in 
  places 
  of 
  40 
  or 
  50 
  feet 
  above 
  the 
  water, 
  having 
  perpendicu- 
  

   lar 
  faces 
  along 
  cleavage 
  surfaces. 
  

  

  The 
  highest 
  land 
  about 
  the 
  lake 
  is 
  north 
  and 
  west 
  of 
  Con- 
  

   glomerate 
  Bay, 
  and 
  in 
  the 
  peninsula 
  between 
  it 
  and 
  Northwest 
  

   Bay. 
  Except 
  for 
  a 
  fringe 
  of 
  the 
  Conglomerate 
  and 
  lower 
  

   limestone 
  (Formations 
  I 
  and 
  II) 
  along 
  Northwest 
  Bay, 
  and 
  of 
  

   the 
  upper 
  horizons 
  of 
  the 
  series 
  east 
  of 
  the 
  fault 
  line 
  that 
  

   crosses 
  the 
  southeast 
  extremity, 
  the 
  peninsula 
  is 
  composed 
  

   entirely 
  of 
  the 
  basement 
  gneisses 
  and 
  granites, 
  which 
  rise 
  from 
  

   the 
  water 
  west 
  of 
  Conglomerate 
  Bay 
  in 
  a 
  steep 
  cliff 
  (along 
  a 
  

   surface 
  of 
  faulting) 
  100 
  feet 
  or 
  more 
  high. 
  The 
  hills 
  in 
  the 
  

   northern 
  part 
  of 
  the 
  peninsula 
  may 
  reach 
  a 
  height 
  of 
  over 
  300 
  

   feet, 
  but 
  this 
  as 
  well 
  as 
  other 
  figures 
  concerning 
  elevations 
  is 
  

   an 
  eye-estimate 
  only, 
  and 
  not 
  a 
  measurement. 
  

  

  Geology. 
  

  

  The 
  rocks 
  exposed 
  around 
  the 
  shores 
  of 
  Steep 
  Rock 
  Lake 
  and 
  

   of 
  Lake 
  Margaret, 
  are 
  divisible 
  into 
  three 
  principal 
  groups. 
  

   The 
  lower 
  division 
  consists 
  of 
  granites 
  and 
  gneisses, 
  which 
  

   typically 
  are 
  medium 
  grained, 
  hornblendic, 
  and 
  granitoid, 
  with 
  

   faint 
  foliation. 
  Locally 
  they 
  present 
  considerable 
  variations 
  in 
  

   composition 
  and 
  very 
  great 
  variations 
  in 
  structure. 
  

  

  Resting 
  upon 
  these 
  basement 
  rocks 
  is 
  a 
  series 
  of 
  rocks 
  show- 
  

   ing 
  a 
  thickness 
  of 
  about 
  5000 
  feet 
  in 
  exposure 
  along 
  the 
  

   shores 
  of 
  the 
  lake. 
  Upper 
  members 
  that 
  are 
  not 
  seen 
  upon 
  

   the 
  lake 
  probably 
  exist 
  in 
  the 
  trough 
  of 
  the 
  eastern 
  synclinal, 
  

   southeast 
  of 
  Jack 
  Pine 
  Pt. 
  The 
  series 
  is 
  divisable 
  into 
  nine 
  

   formation 
  which 
  as 
  far 
  as 
  known 
  are 
  perfectly 
  persistent 
  along 
  

   the 
  strike 
  throughout 
  the 
  area 
  studied. 
  It 
  offers 
  many 
  impor- 
  

   tant 
  points 
  of 
  difference, 
  lithologically, 
  in 
  structure, 
  and 
  in 
  its 
  

   relations 
  to 
  the 
  underlying 
  granites, 
  from 
  any 
  series 
  of 
  rocks 
  

   previously 
  described 
  in 
  western 
  Ontario. 
  Leaving 
  the 
  ques- 
  

   tion 
  of 
  correlation 
  to 
  be 
  discussed 
  after 
  the 
  series 
  has 
  been 
  

   described 
  it 
  will 
  be 
  called 
  for 
  purposes 
  of 
  description 
  in 
  this 
  

   paper, 
  the 
  Steep 
  Rock 
  Series. 
  

  

  At 
  the 
  southeastern 
  extremity 
  of 
  the 
  eastern 
  arm, 
  at 
  the 
  

   north 
  end 
  of 
  the 
  portage 
  into 
  Lake 
  Margaret, 
  lying 
  across 
  the 
  

   edges 
  of 
  the 
  Steep 
  Rock 
  Series, 
  begins 
  a 
  succession 
  of 
  later 
  

   granite 
  porphyries, 
  and 
  massive 
  hornblende 
  rocks, 
  striking 
  

  

  