﻿148 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  chapter 
  in 
  connection 
  with 
  the 
  stratigraphy 
  [p. 
  129]. 
  The 
  valley 
  

   and 
  scarp 
  topography 
  is 
  certainly 
  older, 
  at 
  least 
  in 
  great 
  part, 
  than 
  

   the 
  latest 
  glaciation. 
  

  

  Plains 
  of 
  deposition. 
  Flat 
  stretches 
  of 
  detrital 
  deposits 
  occupy 
  

   the 
  valleys 
  and 
  basins 
  in 
  the 
  northern 
  part 
  of 
  our 
  area 
  and 
  the 
  low- 
  

   lands 
  in 
  the 
  southern 
  part. 
  They 
  are 
  broadly 
  developed 
  over 
  the 
  

   southwestern 
  part 
  of 
  the 
  area, 
  covering 
  nearly 
  all 
  of 
  the 
  Cape 
  Mn- 
  

   cent 
  sheet 
  and 
  a 
  large 
  part 
  of 
  the 
  inferior 
  levels 
  of 
  the 
  Clayton 
  sheet. 
  

   Doubtless 
  the 
  more 
  elevated 
  of 
  these 
  detrital 
  plains 
  have 
  rock 
  floors, 
  ' 
  

   those 
  about 
  Lafargeville 
  and 
  Clayton 
  for 
  instance, 
  but 
  the 
  rock 
  is 
  

   masked; 
  while 
  the 
  valley 
  and 
  basin 
  fillings 
  are 
  deep 
  clay. 
  

  

  These 
  plains 
  are 
  chiefly 
  clay, 
  though 
  sometimes 
  sandy 
  silt 
  and 
  

   occasionally 
  sand. 
  They 
  represent 
  the 
  distributing 
  and 
  leveling 
  

   work 
  of 
  standing 
  waters. 
  Lake 
  Iroquois 
  and 
  Gilbert 
  gulf, 
  and 
  are 
  de- 
  

   scribed 
  with 
  reference 
  to 
  origin 
  in 
  a 
  later 
  chapter, 
  page 
  156. 
  The 
  

   best 
  example 
  of 
  the 
  sand 
  plains 
  may 
  be 
  seen 
  3 
  miles 
  southwest 
  of 
  

   Theresa, 
  crossed 
  by 
  the 
  Clayton 
  branch 
  of 
  the 
  New 
  York 
  Central 
  

   Railroad 
  between 
  Theresa 
  Junction 
  and 
  Strough. 
  Beyond 
  this, 
  both 
  

   east 
  and 
  west 
  of 
  Lafargeville, 
  the 
  plains 
  are 
  clay. 
  From 
  the 
  trains 
  

   on 
  the 
  Cape 
  Vincent 
  branch 
  of 
  the 
  railroad 
  the 
  clay 
  plains 
  may 
  be 
  

   seen 
  spread 
  far 
  and 
  wide, 
  as 
  flat 
  as 
  a 
  prairie, 
  all 
  the 
  way 
  from 
  

   Limerick 
  to 
  Cape 
  Vincent, 
  with 
  a 
  few 
  interruptions 
  of 
  rock 
  or 
  of 
  

   till 
  ridges. 
  

  

  The 
  more 
  extensive, 
  upland 
  clay 
  plains 
  shade 
  ofl:' 
  into 
  till, 
  while 
  

   some 
  of 
  the 
  valley 
  clays 
  are 
  conspicuously 
  pitted, 
  as 
  if 
  deposited 
  

   over 
  ice 
  [p. 
  158,. 
  pi. 
  47]. 
  

  

  Lake 
  basins. 
  Perhaps 
  the 
  most 
  puzzling 
  of 
  the 
  physiographic 
  

   features 
  are 
  the 
  basins 
  or 
  basinlike 
  valleys 
  with 
  steep 
  rock 
  w^alls. 
  

   These 
  are 
  more 
  striking 
  in 
  the 
  district 
  of 
  Potsdam 
  and 
  Precambric 
  

   rocks 
  of 
  the 
  Alexandria 
  quadrangle, 
  where 
  they 
  hold 
  an 
  interesting 
  

   group 
  of 
  lakes, 
  the 
  only 
  lakes 
  in 
  our 
  area, 
  excepting 
  Hyde 
  and 
  

   Perch 
  lakes 
  on 
  the 
  Theresa 
  quadrangle. 
  The 
  five 
  lakes 
  of 
  our 
  

   area, 
  near 
  Redwood, 
  shown 
  in 
  plate 
  47, 
  are 
  only 
  the 
  western 
  mem- 
  

   bers 
  of 
  a 
  large 
  group. 
  Some 
  basins 
  without 
  lakes 
  and 
  some 
  steep- 
  

   walled 
  valleys 
  in 
  limestones 
  on 
  the 
  Theresa 
  and 
  Clayton 
  sheets 
  are 
  

   probably 
  of 
  similar 
  genesis. 
  

  

  Two 
  facts 
  in 
  connection 
  with 
  these 
  basins 
  are 
  specially 
  to 
  be 
  

   noted, 
  the 
  steep, 
  scarplike 
  rock 
  walls 
  and 
  the 
  very 
  small 
  amount 
  

   of 
  glacial 
  drift. 
  These 
  features 
  seem 
  abnormal 
  in 
  a 
  district 
  that 
  

   has 
  been 
  subjected 
  to 
  probably 
  repeated 
  glaciation. 
  While 
  these 
  de- 
  

   pressions 
  are 
  mostly 
  oriented 
  in 
  general 
  harmony 
  with 
  the 
  physio- 
  

   graphic 
  alinement 
  of 
  the 
  region, 
  having 
  a 
  northeast-southwest 
  atti- 
  

  

  