﻿FOURTH 
  REPORT 
  OF 
  THE 
  DIRECTOR 
  I907 
  29 
  

  

  northeastward 
  from 
  Fort 
  Hunter 
  and 
  they 
  are 
  found 
  conspicuously 
  

   developed 
  as 
  appears 
  by 
  the 
  map, 
  from 
  Hoffmans 
  Ferry 
  toward 
  

   Schenectady. 
  Doubtless 
  these 
  deposits 
  were 
  much 
  more 
  extensive 
  

   than 
  they 
  are 
  at 
  present, 
  having 
  been 
  largely 
  swept 
  away 
  by 
  the 
  

   waters 
  of 
  the 
  river 
  after 
  Lake 
  Albany 
  subsided. 
  Reference 
  has 
  

   been 
  made 
  to 
  the 
  heavy 
  tills 
  of 
  the 
  Mohawk 
  valley. 
  These 
  are 
  

   basal 
  and 
  massive 
  on 
  both 
  sides 
  of 
  the 
  river. 
  At 
  certain 
  points 
  as 
  

   already 
  described, 
  they 
  are 
  capped 
  by 
  the 
  lacustrine 
  silts 
  and 
  sands 
  

   of 
  the 
  higher 
  level, 
  but 
  in 
  many 
  cases 
  these 
  sands, 
  which 
  must 
  have 
  

   sloped 
  down 
  to 
  the 
  flood 
  plain 
  level 
  originally, 
  and 
  amassed 
  tills, 
  

   have 
  been 
  swept 
  away 
  along 
  the 
  lower 
  slopes 
  so 
  that 
  in 
  cross-section 
  

   we 
  should 
  have 
  massive 
  tills 
  sloping 
  from 
  the 
  upland 
  down 
  to 
  the 
  

   river. 
  At 
  certain 
  points, 
  as 
  east 
  of 
  Fultonville 
  and 
  along 
  all 
  the 
  

   lower 
  parts 
  of 
  the 
  city 
  of 
  Amsterdam, 
  are 
  belts 
  of 
  water-swept 
  till. 
  

   Along 
  these 
  lower 
  grounds 
  of 
  the 
  city 
  of 
  Amsterdam 
  till 
  is 
  very 
  

   thin, 
  bed 
  rock 
  near 
  at 
  hand, 
  and 
  east 
  of 
  the 
  city 
  are 
  fields 
  

   of 
  boulders 
  which 
  apparently 
  are 
  remnants 
  of 
  tills 
  of 
  which 
  

   great 
  Iroquois 
  currents 
  have 
  removed 
  finer 
  materials. 
  For 
  many 
  

   miles 
  along 
  the 
  Mohawk 
  river 
  the 
  deposits 
  of 
  the 
  drift 
  are 
  exceed- 
  

   ingly 
  steep. 
  They 
  are 
  almost 
  cliffs 
  and 
  there 
  is 
  an 
  entire 
  absence 
  of 
  

   morainic 
  contours. 
  These 
  forms 
  could 
  not 
  have 
  been 
  constructional 
  

   in 
  the 
  glacial 
  sense. 
  When 
  these 
  tills 
  were 
  dumped 
  into 
  the 
  Mo- 
  

   hawk 
  valley 
  they 
  must 
  have 
  been 
  purely 
  morainic 
  forms 
  resulting 
  

   from 
  a 
  melting 
  down 
  of 
  the 
  ice 
  tongues 
  which 
  occupied 
  the 
  valley. 
  

   It 
  would 
  seem 
  that 
  these 
  slopes 
  of 
  till 
  with 
  their 
  occasional 
  covers 
  

   of 
  the 
  customary 
  silts 
  have 
  been 
  powerfully 
  undercut 
  by 
  Iroquois 
  

   waters, 
  giving 
  the 
  steep 
  slopes 
  of 
  the 
  present, 
  but 
  it 
  must 
  also 
  be 
  

   recognized 
  that 
  that 
  undercutting 
  could 
  not 
  effectively 
  take 
  place 
  

   until 
  there 
  was 
  some 
  subsidence 
  of 
  Lake 
  Albany 
  waters 
  allowing 
  

   effective 
  current 
  action 
  by 
  the 
  grade 
  stream 
  carrying 
  the 
  drainage 
  

   of 
  the 
  glacial 
  Great 
  Lakes. 
  These 
  facts 
  and 
  suppositions 
  involve 
  a 
  

   problem 
  concerning 
  the 
  Iroquois 
  drainage 
  and 
  the 
  waters 
  of 
  Lake 
  

   Albany 
  which 
  deserves 
  further 
  and 
  more 
  final 
  investigation. 
  An 
  

   interesting 
  remnant 
  of 
  the 
  Lake 
  Albany 
  silts 
  is 
  found 
  near 
  South 
  

   Schenectady 
  along 
  the 
  'waters 
  of 
  the 
  Normans 
  kill. 
  Here, 
  near 
  the 
  

   region 
  of 
  the 
  Amsterdam 
  quadrangle 
  is 
  a 
  small 
  embayment 
  of 
  Lake 
  

   Albany 
  waters 
  and 
  therefore 
  a 
  reentrant 
  area 
  of 
  sands 
  which 
  joined 
  

   with 
  the 
  greater 
  area 
  that 
  appears 
  in 
  the 
  Schenectady 
  quadrangle. 
  

   Schoharie 
  lake. 
  An 
  interesting 
  development 
  of 
  lacustrine 
  sands 
  

   and 
  clays 
  is 
  found 
  along 
  the 
  Schoharie 
  river 
  from 
  Esperance 
  up 
  

   stream 
  for 
  some 
  miles. 
  In 
  looking 
  for 
  a 
  cause 
  of 
  these 
  lacustrine 
  

  

  