﻿H. 
  L. 
  Smyth 
  — 
  Geology 
  of 
  Steep 
  Rock 
  Lake, 
  Ont. 
  321 
  

  

  All 
  these 
  granitic 
  rocks 
  are 
  traversed 
  by 
  an 
  immense 
  number 
  

   of 
  dikes 
  of 
  greenstone, 
  and 
  more 
  rarely 
  of 
  quartz 
  porphyry, 
  

   all 
  of 
  which 
  for 
  structural 
  reasons 
  are 
  conveniently 
  considered 
  

   with 
  the 
  basement 
  complex. 
  

  

  These 
  belong 
  to 
  three 
  eras 
  of 
  irruption. 
  (1) 
  Those 
  which 
  

   supplied 
  pebbles 
  to 
  the 
  conglomerate 
  at 
  the 
  base 
  of 
  the 
  Steep 
  

   Rock 
  series. 
  (2) 
  Those 
  which 
  are 
  seen 
  to 
  traverse 
  both 
  the 
  

   granitic 
  and 
  Steep 
  Rock 
  series, 
  and 
  to 
  have 
  participated 
  in 
  the 
  

   folding. 
  (3) 
  A 
  single 
  massive 
  dike 
  of 
  porphyrite 
  (?), 
  which 
  

   cuts 
  through 
  the 
  most 
  schistose 
  phase 
  of 
  the 
  granite 
  at 
  the 
  

   turn 
  of 
  the 
  sharp 
  fold 
  at 
  the 
  head 
  of 
  E".W. 
  Bay. 
  and 
  is 
  clearly 
  

   subsequent 
  to 
  the 
  latest 
  period 
  of 
  folding 
  of 
  the 
  region. 
  The 
  

   dikes 
  of 
  class 
  2 
  are 
  best 
  seen 
  along 
  the 
  ^s.E. 
  shore 
  of 
  East 
  

   Bay. 
  They 
  are 
  rudely 
  parallel, 
  the 
  walls 
  are 
  straight 
  and 
  

   nearly 
  vertical, 
  trending 
  from 
  X. 
  45° 
  to 
  N. 
  65° 
  E., 
  and 
  in 
  a 
  

   general 
  way 
  cutting 
  the 
  granites 
  and 
  the 
  lower 
  horizons 
  of 
  tne 
  

   S. 
  R. 
  series 
  in 
  a 
  direction 
  normal 
  to 
  the 
  contact 
  and 
  strike. 
  

   They 
  vary 
  in 
  width 
  from 
  one 
  to 
  two 
  feet 
  up 
  to 
  TO 
  feet, 
  and 
  

   clearly 
  were 
  the 
  chimneys 
  through 
  which 
  passed 
  up 
  the 
  mate- 
  

   rial 
  for 
  the 
  great 
  mass 
  of 
  interbedded 
  traps 
  on 
  the 
  south 
  side 
  

   of 
  the 
  same 
  arm. 
  

  

  The 
  contact 
  phenomena 
  with 
  the 
  country 
  rock 
  are 
  uniformly 
  

   as 
  follows 
  : 
  When 
  the 
  dike 
  is 
  less 
  than 
  6 
  or 
  8 
  feet 
  in 
  width 
  it 
  

   is 
  fine 
  grained, 
  without 
  crystalline 
  structure, 
  and 
  throughout 
  

   is 
  highly 
  schistose 
  in 
  the 
  general 
  regional, 
  direction. 
  The 
  

   wider 
  dikes 
  have 
  massive 
  and 
  crystalline 
  interiors, 
  but 
  are 
  fine 
  

   grained 
  and 
  schistose 
  in 
  a 
  direction 
  parallel 
  to 
  the 
  induced 
  

   regional 
  cleavage, 
  for 
  a 
  distance 
  of 
  2 
  J 
  or 
  3 
  feet 
  from 
  the 
  wall. 
  

   The 
  country 
  rock 
  also 
  is 
  schistose 
  next 
  to 
  the 
  wall 
  of 
  the 
  dike, 
  

   the 
  belt 
  affected 
  being 
  narrower 
  where 
  the 
  adjacent 
  rock 
  is 
  

   granite 
  than 
  where 
  it 
  is 
  limestone. 
  

  

  With 
  regard 
  to 
  distribution, 
  it 
  may 
  be 
  said 
  in 
  a 
  general 
  way 
  

   that 
  all 
  shore 
  lines 
  north 
  of 
  the 
  water, 
  from 
  Lake 
  Margaret 
  to 
  

   Xorthwest 
  Bay, 
  are. 
  with 
  few 
  exceptions, 
  made 
  up 
  of 
  the 
  

   rocks 
  of 
  the 
  basement 
  complex. 
  The 
  exceptions 
  are 
  the 
  head- 
  

   lands 
  in 
  East 
  Bay 
  and 
  at 
  the 
  Elbow 
  which 
  are 
  of 
  limestone. 
  

   the 
  great 
  mass 
  of 
  limestone 
  at 
  the 
  head 
  of 
  Falls 
  Bay, 
  and 
  the 
  

   limestone 
  between 
  Camp 
  Bay 
  and 
  Conglomerate 
  Bay, 
  and 
  the 
  

   Conglomerate 
  along 
  the 
  latter. 
  

  

  Steep 
  Bock 
  Series. 
  — 
  The 
  Steep 
  Rock 
  series 
  consist 
  of 
  9 
  

   well 
  marked 
  and 
  persistent 
  horizons 
  exposed 
  about 
  the 
  lake. 
  

   It 
  is 
  very 
  probable 
  that 
  other 
  higher 
  members 
  exist 
  in 
  the 
  land 
  

   area 
  southeast 
  of 
  the 
  shore 
  from 
  Jack 
  Pine 
  Pt. 
  to 
  Pine 
  Beach. 
  

   The 
  9 
  formations 
  are 
  given 
  in 
  the 
  table 
  below 
  which 
  reads 
  

   upward 
  in 
  ascending 
  order 
  : 
  

  

  