﻿GEOLOGY 
  OF 
  THOUSAND 
  ISLANDS 
  REGION 
  6/ 
  

  

  Ells 
  the 
  Theresa 
  formation 
  outcrops 
  on 
  Howe 
  island, 
  and 
  on 
  the 
  

   Canadian 
  mainland 
  to 
  a 
  point 
  midway 
  between 
  Gananoque 
  and 
  

   Kingston.^ 
  In 
  the 
  district 
  about 
  Kingston, 
  as 
  seen 
  by 
  us 
  in 
  

   1908 
  under 
  Dr 
  Ami's 
  guidance, 
  the 
  Potsdam 
  is 
  certainly 
  present, 
  

   though 
  no 
  Theresa 
  was 
  seen. 
  The 
  Potsdam 
  is 
  in 
  patchy 
  distri- 
  

   bution, 
  in 
  depressions 
  of 
  the 
  old 
  Precambric 
  surface, 
  and 
  is 
  still 
  

   thinner 
  than 
  it 
  is 
  at 
  Clayton. 
  The 
  Theresa 
  may 
  never 
  have 
  

   been 
  deposited 
  here, 
  or 
  it 
  may 
  have 
  been 
  thinly 
  laid 
  down 
  and 
  

   then 
  eroded, 
  prior 
  to 
  Pamelia 
  deposition. 
  But 
  it 
  certainly 
  seems 
  

   as 
  if, 
  here 
  at 
  Kingston, 
  we 
  are 
  very 
  near 
  the 
  westerly 
  end 
  of 
  this 
  

   old, 
  St 
  Lawrence, 
  Upper 
  Cambric 
  trough. 
  

  

  On 
  the 
  basis 
  of 
  its 
  fauna 
  and 
  position 
  the 
  Potsdam 
  sandstone 
  

   of 
  northern 
  New 
  York 
  was 
  classified 
  as 
  of 
  Upper 
  Cambric 
  age 
  by 
  

   Walcott, 
  and 
  in 
  this 
  he 
  has 
  been 
  followed 
  by 
  practically 
  all 
  

   geologists. 
  One 
  can 
  start 
  on 
  the 
  formation 
  at 
  Lake 
  Champlain 
  

   and 
  follow 
  it 
  without 
  a 
  break 
  to 
  Clayton, 
  as 
  a 
  single 
  continuous 
  

   sandstone 
  formation. 
  Unquestionably 
  its 
  deposition 
  commenced 
  

   first 
  at 
  the 
  east, 
  and 
  gradually 
  extended 
  westward; 
  unquestion- 
  

   ably 
  the 
  basal 
  portion 
  in 
  the 
  western 
  sections 
  is 
  younger 
  than 
  the 
  

   base 
  in 
  the 
  east. 
  But, 
  so 
  far 
  as 
  known 
  to 
  us, 
  there 
  is 
  not 
  a 
  scrap 
  

   of 
  evidence 
  to 
  show 
  that 
  the 
  deposition 
  of 
  sand 
  had 
  ceased, 
  and 
  

   that 
  of 
  dolomite 
  begun 
  on 
  the 
  east, 
  before 
  sand 
  deposit 
  had 
  

   even 
  commenced 
  on 
  the 
  west. 
  And 
  even 
  were 
  this 
  true, 
  as 
  is 
  

   quite 
  possible, 
  there 
  is 
  certainly 
  no 
  evidence 
  of 
  such 
  considerable 
  

   age 
  difference 
  between 
  the 
  eastern 
  and 
  western 
  ends 
  of 
  the 
  

   formation, 
  as 
  to 
  warrant 
  their 
  classification 
  in 
  two 
  entirely 
  dif- 
  

   ferent 
  geologic 
  periods, 
  the 
  one 
  end 
  Cambric, 
  the 
  other 
  Ordovicic, 
  

   as 
  has 
  been 
  recently 
  done 
  by 
  Professor 
  Grabau, 
  who 
  classes 
  the 
  

   Potsdam 
  here 
  as 
  of 
  Beekmantown 
  age.^ 
  That 
  seems 
  to 
  us 
  a 
  

   stretching 
  of 
  facts 
  to 
  fit 
  theory 
  that 
  is 
  certainly 
  not 
  permissible. 
  

   It 
  is 
  quite 
  possibly 
  true 
  that 
  the 
  sandstone 
  deposition 
  slowly 
  

   worked 
  its 
  way 
  westward 
  by 
  progressive 
  overlap, 
  as 
  the 
  trough 
  

   continued 
  to 
  subside 
  ; 
  but 
  the 
  evidence 
  seems 
  to 
  us 
  to 
  indicate 
  

   c'learly 
  that 
  the 
  length 
  of 
  time 
  consumed 
  in 
  the 
  process 
  is 
  far 
  less 
  

   than 
  Grabau 
  would 
  have 
  us 
  believe. 
  We 
  have 
  now 
  gathered 
  

   evidence 
  from 
  many 
  points 
  in 
  New 
  York 
  indicating 
  that 
  every- 
  

   where 
  the 
  Beekmantown 
  formation 
  is 
  unconformable 
  on 
  what 
  

   lies 
  beneath. 
  Detailed 
  study 
  of 
  section 
  after 
  section 
  has 
  shown 
  

   the 
  presence 
  of 
  the 
  unconformity 
  in 
  every 
  case 
  ; 
  and 
  though 
  the 
  

  

  ^Ray. 
  Soc. 
  Can. 
  Trans., 
  ser. 
  2, 
  v. 
  9, 
  § 
  4, 
  p. 
  97-108. 
  

   2 
  Science, 
  n. 
  s. 
  29 
  :356-58. 
  

  

  