﻿H. 
  L. 
  Smyth 
  — 
  Geology 
  of 
  Steep 
  jRock 
  Lake, 
  Ont. 
  325 
  

  

  greenish- 
  gray 
  rock, 
  made 
  up 
  of 
  plagioclase 
  and 
  hornblende, 
  

   and 
  is 
  probably 
  a 
  diorite. 
  Locally 
  it 
  includes 
  layers 
  of 
  green 
  

   schist 
  which 
  are 
  to 
  be 
  regarded 
  as 
  mechanical 
  derivatives, 
  

   analogous 
  to 
  the 
  chloritic 
  gneissic 
  phases 
  of 
  the 
  basement 
  

   granite. 
  The 
  formation 
  is 
  best 
  seen 
  south 
  of 
  the 
  eastern 
  arm, 
  

   where 
  it 
  forms 
  a 
  long 
  ridge 
  running 
  from 
  Lake 
  Margaret 
  por- 
  

   tage 
  N.W. 
  to 
  Falls 
  Bay, 
  and 
  in 
  the 
  two 
  natural 
  sections 
  made 
  

   by 
  the 
  shore 
  line 
  at 
  both 
  the 
  northern 
  and 
  southern 
  ends. 
  

   Small 
  patches 
  are 
  exposed 
  at 
  a 
  number 
  of 
  localities 
  about 
  the 
  

   lake. 
  It 
  is 
  uncertain 
  whether 
  this 
  is 
  an 
  intrusive 
  sheet 
  or 
  a 
  

   flow. 
  

  

  Formation 
  V 
  is 
  a 
  very 
  calcareous 
  green 
  schist 
  containing 
  

   thin 
  seams 
  of 
  limestone. 
  The 
  included 
  layers 
  are 
  quite 
  pure 
  

   finely 
  crystalline 
  limestone. 
  Thin 
  sections 
  of 
  the 
  less 
  cal- 
  

   careous 
  portion 
  show 
  that 
  the 
  rock 
  consists 
  of 
  50 
  to 
  60 
  per 
  

   cent 
  of 
  calcite, 
  and 
  for 
  the 
  rest, 
  of 
  argillaceous 
  material 
  and 
  

   secondary 
  quartz. 
  Originally 
  it 
  was 
  probably 
  in 
  the 
  main 
  a 
  

   very 
  calcareous 
  shale, 
  with 
  thin 
  beds 
  of 
  limestone. 
  The 
  thick- 
  

   ness 
  is 
  about 
  600 
  feet. 
  

  

  Immediately 
  above 
  the 
  limestone 
  comes 
  Formation 
  VI, 
  a 
  

   conglomerate, 
  having 
  a 
  maximum 
  thickness 
  of 
  about 
  100 
  feet. 
  

   It 
  varies 
  in 
  habit, 
  from 
  a 
  hydromica 
  schist, 
  carrying 
  many 
  

   grains 
  of 
  quartz, 
  the 
  clastic 
  character 
  of 
  which 
  is 
  evident 
  in 
  

   thin 
  section, 
  to 
  a 
  rather 
  coarse 
  conglomerate, 
  the 
  pebbles 
  in 
  

   which 
  seem 
  to 
  be 
  entirely 
  of 
  quartz 
  and 
  granite. 
  The 
  locality 
  

   in 
  which 
  it 
  may 
  be 
  best 
  seen 
  is 
  on 
  Falls 
  Bay, 
  on 
  the 
  shore 
  east 
  

   of 
  Jack 
  Pine 
  Point. 
  

  

  Formation 
  VII. 
  The 
  type 
  rock 
  of 
  this 
  horizon 
  is 
  a 
  light 
  

   greenish 
  gray, 
  massive, 
  close 
  textured 
  rock, 
  which 
  weathers 
  a 
  

   light 
  brown. 
  In 
  thin 
  section 
  it 
  appears 
  to 
  be 
  of 
  eruptive 
  

   origin, 
  but 
  owing 
  to 
  the 
  complete 
  alteration 
  of 
  the 
  bisilicate 
  it 
  

   is 
  uncertain 
  whether 
  it 
  was 
  originally 
  a 
  diabase 
  or 
  a 
  diorite. 
  

   Departing 
  from 
  this 
  as 
  a 
  type, 
  on 
  the 
  one 
  hand 
  are 
  found 
  

   members 
  which 
  show 
  crystalline 
  structure 
  macroscopically, 
  

   and 
  on 
  the 
  other 
  banded 
  green 
  schists 
  which 
  to 
  the 
  eye 
  have 
  

   every 
  appearance 
  of 
  being 
  altered 
  sediments. 
  Under 
  the 
  

   microscope 
  however 
  they 
  show 
  no 
  trace 
  of 
  sedimentary 
  origin. 
  

   This 
  banding 
  is 
  of 
  two 
  kinds. 
  (1), 
  a 
  fine 
  banding 
  due 
  to 
  an 
  

   alternation 
  of 
  thin 
  seams 
  differing 
  slightly 
  from 
  one 
  another 
  

   in 
  color 
  and 
  in 
  texture. 
  (2), 
  a 
  coarser, 
  due 
  to 
  the 
  interbedding 
  

   of 
  layers 
  of 
  the 
  massive 
  varieties 
  with 
  the 
  schistose. 
  These 
  

   layers 
  are 
  of 
  all 
  thicknesses, 
  from 
  a 
  few 
  inches 
  up 
  to 
  several 
  

   feet. 
  . 
  The 
  structure, 
  of 
  both 
  varieties, 
  appears 
  to 
  be 
  antece- 
  

   dent 
  to 
  the 
  last 
  folding 
  of 
  the 
  series, 
  since 
  it 
  is 
  often 
  greatly 
  

   contorted, 
  and 
  frequently 
  intersected 
  by 
  the 
  regional 
  cleavage, 
  

   and 
  in 
  general 
  is 
  parallel 
  to 
  the 
  true 
  strike. 
  A 
  graphitic 
  schist, 
  

   twenty 
  feet 
  or 
  more 
  in 
  thickness, 
  is 
  also 
  included. 
  There 
  is 
  an 
  

  

  