﻿354 
  Spencer 
  — 
  Origin 
  and 
  Age 
  of 
  the 
  Ontario 
  Shore-Line. 
  

  

  Toronto 
  Island. 
  — 
  The 
  enormous 
  mass 
  of 
  sand 
  deposited 
  

   here 
  is 
  of 
  more 
  than 
  local 
  interest, 
  having 
  given 
  rise 
  to 
  fatal 
  

   chronological 
  speculations. 
  Its 
  origin 
  is 
  much 
  more 
  complex 
  

   than 
  that 
  of 
  wave-assorted 
  beach 
  materials 
  transported 
  by 
  cur- 
  

   rents 
  from 
  the 
  drift 
  bluffs 
  of 
  Scarboro 
  and 
  deposited 
  in 
  front 
  

   of 
  Toronto 
  Harbour. 
  Its 
  history 
  could 
  not 
  be 
  separated 
  from 
  

   that 
  of 
  the 
  whole 
  Ontario 
  shore, 
  nor 
  understood 
  without 
  the 
  

   study 
  of 
  the 
  invaluable 
  surveys 
  made 
  for 
  the 
  Toronto 
  Water 
  

   Supply. 
  

  

  The 
  floor 
  of 
  Lake 
  Ontario 
  is 
  generally 
  a 
  uniform 
  plain, 
  slop- 
  

   ing 
  outward 
  from 
  its 
  northern 
  shore, 
  at 
  about 
  50 
  feet 
  per 
  mile 
  

   to 
  a 
  depth 
  of 
  more 
  than 
  300 
  feet, 
  in 
  contrast 
  with 
  the 
  steps, 
  

   which 
  occur 
  beneath 
  the 
  southern 
  side 
  of 
  the 
  lake. 
  In 
  the 
  

   vicinity 
  of 
  Toronto, 
  the 
  map 
  of 
  Chipman 
  and 
  Powers 
  (fig. 
  1) 
  

   shows 
  the 
  lake 
  deepening 
  gradually 
  to 
  50 
  feet, 
  from 
  a 
  mile 
  to 
  

   a 
  mile 
  and 
  a 
  half 
  from 
  the 
  shore, 
  beyond 
  which 
  the 
  75-foot 
  con- 
  

   tour 
  is 
  irregular, 
  varying 
  from 
  2 
  to 
  3J 
  miles. 
  This 
  encircles 
  

   the 
  great 
  Humber 
  Embayment, 
  and 
  the 
  smaller 
  indentations 
  off 
  

   the 
  Woodbine 
  and 
  off 
  Victoria 
  Park. 
  A 
  steeper 
  slope, 
  begin- 
  

   ning 
  at 
  75-100 
  feet 
  and 
  reaching 
  to 
  a 
  depth 
  of 
  175 
  or 
  

   even 
  250 
  feet, 
  extends 
  along 
  the 
  coast 
  for 
  12 
  miles, 
  thus 
  

   producing 
  a 
  slight 
  shelf-like 
  form, 
  which 
  disappears 
  at 
  

   either 
  end 
  of 
  this 
  section. 
  The 
  shelf 
  sends 
  out 
  a 
  tongue 
  

   between 
  the 
  embayments 
  of 
  Woodbine 
  and 
  Victoria 
  Park, 
  

   (where 
  the 
  wave 
  action 
  is 
  of 
  little 
  consequence) 
  to 
  a 
  distance 
  

   of 
  3 
  miles 
  from 
  the 
  low 
  shore. 
  These 
  indentations, 
  as 
  well 
  as 
  

   the 
  Hum 
  bar 
  Embayment, 
  are 
  partly 
  re-filled 
  inter-Glacial 
  or 
  

   pre- 
  Ontario 
  land 
  valleys. 
  

  

  One 
  of 
  the 
  inter- 
  Glacial 
  valleys 
  in 
  the 
  floor 
  of 
  Lake 
  Ontario 
  

   is 
  brought 
  to 
  light 
  by 
  borings 
  in 
  front 
  of 
  Victoria 
  Park 
  (sec- 
  

   tion 
  B, 
  flg. 
  2). 
  An 
  older 
  inter-Glacial 
  valley 
  to 
  the 
  east 
  in 
  

   Scarboro 
  Bluffs 
  was 
  discovered 
  by 
  Dr. 
  G. 
  J. 
  Hinde, 
  and 
  re- 
  

   described 
  by 
  Prof. 
  A. 
  P. 
  Coleman, 
  but 
  its 
  natural 
  extension 
  to 
  

   the 
  lake 
  is 
  re-fllled, 
  concealing 
  its 
  corresponding 
  embayment. 
  

  

  The 
  line 
  of 
  borings 
  outward 
  from 
  Victoria 
  Park 
  shows 
  that 
  

   the 
  rocky 
  basement 
  beneath 
  the 
  lake 
  is 
  covered 
  by 
  only 
  about 
  

   30 
  feet 
  of 
  inter-Glacial 
  clays 
  and 
  sands. 
  Another 
  line 
  of 
  bor- 
  

   ings, 
  4ij 
  miles 
  to 
  the 
  east, 
  in 
  front 
  of 
  Scarboro 
  Bluffs, 
  also 
  

   shows 
  30 
  feet 
  of 
  sand 
  and 
  clay 
  covering 
  the 
  rocky 
  basement 
  of 
  

   the 
  lake 
  (section 
  C, 
  fig. 
  2). 
  The 
  lake 
  floor 
  here 
  slopes 
  uniformly 
  

   for 
  2 
  miles 
  to 
  a 
  depth 
  of 
  85 
  or 
  90 
  feet, 
  and 
  somewhat 
  more 
  

   rapidly 
  beyond. 
  On 
  either 
  side 
  of 
  this 
  point, 
  the 
  border 
  of 
  the 
  

   shelf 
  varies 
  from 
  1^-2^ 
  miles 
  from 
  the 
  shore. 
  Thus 
  a 
  uniform- 
  

   ity 
  of 
  the 
  lake 
  floor 
  is 
  shown 
  in 
  front 
  of 
  either 
  the 
  lower 
  or 
  the 
  

   higher 
  shore 
  and 
  where 
  there 
  is 
  both 
  little 
  or 
  rapid 
  encroach- 
  

   ment 
  of 
  the 
  lake. 
  

  

  In 
  contrast 
  with 
  these 
  features 
  are 
  those 
  of 
  Toronto 
  bay 
  and 
  

  

  