﻿318 
  H. 
  L. 
  Smyth 
  — 
  Geology 
  of 
  Steep 
  Rook, 
  Lake, 
  Ont. 
  

  

  exit 
  there 
  is 
  no 
  current 
  observable 
  by 
  the 
  eye 
  and 
  the 
  differ- 
  

   ence 
  in 
  level 
  must 
  be 
  exceedingly 
  small. 
  

  

  As 
  regards 
  dimensions: 
  — 
  from 
  the 
  southern 
  extremity 
  of 
  

   the 
  eastern 
  arm 
  to 
  the 
  mouth 
  of 
  the 
  river 
  near 
  the 
  Falls 
  is 
  

   about 
  3-J 
  miles 
  ; 
  from 
  the 
  Falls 
  to 
  the 
  Elbow, 
  3 
  miles 
  ; 
  from 
  

   the 
  Elbow 
  to 
  the 
  Upper 
  Narrows, 
  \\ 
  miles 
  ; 
  and 
  from 
  the 
  

   Upper 
  Narrows 
  south 
  to 
  the 
  Aticokan 
  River 
  3^ 
  miles. 
  The 
  

   entire 
  lake 
  including 
  the 
  portion 
  of 
  Lake 
  Margaret 
  shown 
  on 
  

   the 
  map 
  could 
  be 
  inscribed 
  within 
  a 
  rectangle 
  6 
  miles 
  from 
  

   east 
  to 
  west, 
  and 
  5-J- 
  miles 
  from 
  north 
  to 
  south, 
  or 
  within 
  an 
  

   area 
  of 
  33 
  square 
  miles. 
  As 
  the 
  name 
  implies 
  the 
  lake 
  has 
  

   bold 
  rocky 
  shores, 
  which, 
  in 
  places 
  rise 
  150 
  feet 
  from 
  the 
  

   water 
  in 
  nearly 
  perpendicular 
  cliffs. 
  The 
  total 
  length 
  of 
  shore 
  

   line 
  is 
  approximately 
  28 
  miles 
  not 
  counting 
  the 
  smaller 
  bays 
  

   and 
  indentations. 
  Not 
  less 
  than 
  £■ 
  of 
  this 
  length 
  shows 
  rock 
  

   in 
  place 
  either 
  at 
  the 
  water's 
  edge 
  or 
  within 
  a 
  few 
  hundred 
  

   feet 
  of 
  it, 
  and 
  of 
  this 
  perhaps 
  \ 
  may 
  be 
  studied 
  without 
  leav- 
  

   ing 
  the 
  boat. 
  

  

  The 
  contour 
  of 
  the 
  water 
  line 
  shows 
  a 
  very 
  beautiful 
  depen- 
  

   dence 
  upon 
  structural 
  conditions. 
  The 
  eastern 
  arm 
  follows 
  

   the 
  general 
  strike 
  of 
  the 
  rocks 
  from 
  the 
  bay 
  north 
  of 
  Lake 
  

   Margaret 
  portage 
  northwest 
  to 
  Falls 
  Bay. 
  On 
  the 
  northeast- 
  

   ern 
  shore 
  of 
  this 
  arm 
  the 
  lower 
  limestone 
  makes 
  several 
  bold 
  

   headlands 
  that 
  rise 
  abruptly 
  from 
  60 
  to 
  100 
  feet 
  above 
  the 
  

   water. 
  In 
  the 
  bays 
  between 
  these 
  headlands 
  the 
  basement 
  

   granites 
  intersected 
  by 
  a 
  large 
  number 
  of 
  greenstone 
  dikes 
  

   form 
  the 
  shore, 
  and 
  rise 
  more 
  gently 
  into 
  the 
  broken 
  hum- 
  

   mocky 
  hills 
  that 
  generally 
  characterize 
  the 
  granitic 
  areas 
  of 
  the 
  

   region. 
  A 
  few 
  hundred 
  feet 
  back 
  from 
  the 
  southwestern 
  

   shore 
  the 
  great 
  trap 
  intrusions 
  or 
  flows 
  of 
  Horizon 
  IV 
  make 
  

   a 
  continuous 
  ridge, 
  which 
  is 
  estimated 
  to 
  reach 
  a 
  height 
  of 
  250 
  

   feet 
  above 
  the 
  water. 
  This 
  ridge 
  runs, 
  without 
  interruption, 
  

   the 
  top 
  showing 
  only 
  a 
  few 
  minor 
  sags, 
  from 
  the 
  shore 
  west 
  of 
  

   the 
  portage 
  into 
  Lake 
  Margaret, 
  for 
  3 
  miles 
  along 
  the 
  strike 
  in 
  

   a 
  northwest 
  direction 
  as 
  far 
  as 
  the 
  wide 
  expansion 
  of 
  Falls 
  

   Bay. 
  

  

  The 
  gneissic 
  phases 
  of 
  the 
  granites, 
  and 
  associated 
  irruptives 
  

   compose 
  the 
  west 
  shore 
  of 
  Falls 
  Bay, 
  from 
  the 
  great 
  limestone 
  

   exposure 
  at 
  the 
  head, 
  south 
  to 
  the 
  Elbow. 
  As 
  far 
  south 
  as 
  

   Wiegand's 
  Point, 
  the 
  granite 
  cliffs 
  are 
  high 
  and 
  very 
  steep 
  and 
  

   are 
  broken 
  across 
  only 
  in 
  two 
  or 
  three 
  places. 
  On 
  the 
  south 
  

   shore 
  of 
  Falls 
  Bay 
  from 
  Trap 
  Point 
  to 
  Jack 
  Pine 
  Pt. 
  the 
  shore 
  

   line 
  cuts 
  the 
  strike 
  of 
  the 
  rocks 
  nearly 
  at 
  right 
  angles, 
  and 
  

   from 
  Jack 
  Pine 
  Pt. 
  south 
  to 
  Pine 
  Beach 
  obliquely 
  at 
  a 
  less 
  

   angle. 
  The 
  ridges 
  descend 
  rather 
  gradually 
  to 
  the 
  lake 
  along 
  

   this 
  shore, 
  the 
  harder 
  rocks 
  making 
  little 
  headlands 
  separated 
  

   by 
  sand 
  and 
  shingle 
  beaches. 
  

  

  

  