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  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  show, 
  distinctly 
  recognizes 
  the 
  chief 
  physical 
  oscillation 
  of 
  the 
  

   region. 
  

  

  It 
  would, 
  therefore, 
  appear 
  that 
  some 
  marked 
  but 
  well 
  defined 
  

   change 
  of 
  level 
  occurred 
  in 
  the 
  area 
  south 
  of 
  the 
  Kingston-Brock- 
  

   ville 
  Archaean 
  axis 
  at 
  the 
  close 
  of 
  the 
  Potsdam, 
  which 
  was 
  also 
  

   materially 
  reduced 
  in 
  thickness. 
  This 
  is 
  in 
  marked 
  contrast 
  to 
  the 
  

   conditions 
  which 
  prevailed 
  north 
  of 
  that 
  axis 
  throughout 
  the 
  Ottawa 
  

   basin 
  ; 
  and 
  it 
  may 
  be 
  supposed 
  that, 
  at 
  a 
  certain 
  stage 
  in 
  the 
  de- 
  

   position 
  of 
  the 
  sandstone 
  formation, 
  the 
  surface 
  was 
  raised 
  above 
  

   the 
  level 
  of 
  the 
  sea, 
  and 
  so 
  remained 
  till 
  the 
  beginning 
  of 
  Black 
  

   River 
  time 
  throughout 
  the 
  whole 
  extent 
  of 
  Lake 
  Ontario;^ 
  

  

  Age 
  of 
  the 
  Pamelia 
  formation. 
  Our 
  section 
  here 
  shows 
  the 
  

   Pamelia 
  formation 
  to 
  lie 
  between 
  the 
  Theresa 
  and 
  Lowville 
  forma- 
  

   tions, 
  separated 
  from 
  each 
  by 
  an 
  unconformity, 
  the 
  lower 
  of 
  which 
  

   is 
  much 
  more 
  important 
  than 
  the 
  upper. 
  In 
  the 
  Champlain 
  valley 
  

   two 
  great 
  formations, 
  the 
  Beekmantown 
  and 
  the 
  Chazy, 
  with 
  a 
  

   combined 
  thickness 
  of 
  2000 
  feet, 
  occupy 
  this 
  same 
  interval, 
  yet 
  the 
  

   Pamelia 
  formation 
  is 
  unlike 
  either. 
  On 
  the 
  basis 
  of 
  its 
  position 
  

   and 
  fauna, 
  Ulrich 
  correlates 
  it 
  with 
  the 
  upper 
  part 
  of 
  the 
  Stones 
  

   River 
  formation, 
  a 
  formation 
  of 
  Chazy 
  age, 
  but 
  laid 
  down 
  in 
  a 
  

   separate 
  basin 
  from 
  the 
  Chazy, 
  so 
  that 
  faunally 
  and 
  lithologically 
  

   the 
  two 
  are 
  quite 
  distmct. 
  The 
  Stones 
  River 
  basin 
  lay 
  to 
  the 
  west 
  

   and 
  southwest 
  of 
  the 
  Chazy 
  trough, 
  and 
  was 
  much 
  larger. 
  The 
  

   barrier 
  between 
  the 
  two 
  in 
  New 
  York 
  comprised 
  the 
  Mohawk 
  val- 
  

   ley 
  region, 
  much 
  of 
  the 
  Adirondack 
  district, 
  and 
  at 
  least 
  the 
  west- 
  

   erly 
  portion 
  of 
  the 
  St 
  Lawrence 
  trough. 
  ^ 
  

  

  Curiously 
  too, 
  although 
  much 
  sedimentation 
  occurred 
  in 
  the 
  

   Champlain 
  trough 
  during 
  Beekmantown-Chazy 
  time, 
  and 
  only 
  

   Pamelia 
  deposit 
  in 
  our 
  district 
  here, 
  yet 
  this 
  is 
  practically 
  un- 
  

  

  1 
  Roy. 
  Soc. 
  Can. 
  Trans, 
  ser. 
  2, 
  v. 
  9, 
  § 
  iv, 
  p. 
  106. 
  

  

  It 
  is 
  to 
  be 
  noted 
  that 
  Black 
  River 
  is 
  here 
  used 
  in 
  a 
  general 
  sense 
  as 
  

   including 
  the 
  whole 
  body 
  of 
  limestone. 
  

  

  2 
  Since 
  the 
  above 
  was 
  written 
  another 
  paper 
  by 
  Professor 
  Grabau 
  has 
  

   appeared 
  which 
  presents 
  more 
  definitely 
  his 
  interpretation 
  of 
  the 
  rock 
  suc- 
  

   cession 
  and 
  age 
  in 
  this 
  district 
  [Jour. 
  Geol. 
  17:211-26]. 
  The 
  fundamental 
  

   difiference 
  between 
  us 
  seems 
  to 
  be 
  that 
  he 
  regards 
  the 
  break 
  between 
  the 
  

   Theresa 
  and 
  Pamelia 
  formations 
  as 
  representing 
  the 
  somewhat 
  expanded 
  

   westward 
  continuation 
  of 
  the 
  break 
  in 
  the 
  Champlain 
  valley 
  between 
  the 
  

   Beekmantown 
  and 
  Chazy, 
  and 
  recognizes 
  no 
  break 
  there 
  between 
  the 
  Cam- 
  

   bric 
  and 
  Beekmantown. 
  We 
  regard 
  it 
  as 
  representing 
  most 
  of 
  Beekman- 
  

   town 
  and 
  all 
  of 
  lower 
  and 
  middle 
  Chazy 
  time 
  and 
  think 
  that, 
  to 
  the 
  east 
  

   in 
  the 
  St 
  Lawrence 
  valley, 
  it 
  splits 
  into 
  two 
  breaks 
  with 
  a 
  wedge 
  of 
  later 
  

   Beekmantown 
  inserted 
  between. 
  He 
  thinks 
  there 
  is 
  no 
  Cambric 
  here, 
  and 
  

   that 
  the 
  Potsdam 
  and 
  Theresa 
  are 
  of 
  Beekmantown 
  age; 
  and 
  he 
  recog- 
  

   nizes 
  no 
  break 
  between 
  the 
  Cambric 
  and 
  Ordovicic. 
  We 
  find 
  evidence 
  of 
  

   a 
  considerable 
  series 
  of 
  oscillations 
  of 
  level 
  in 
  the 
  general 
  region, 
  while 
  he 
  

   argues, 
  if 
  we 
  correctly 
  understand 
  him, 
  for 
  a 
  slow, 
  progressive 
  subsidence 
  

   of 
  the 
  region 
  during 
  Potsdam 
  and 
  Beekmantown 
  time. 
  

  

  