﻿HYDROLOGY 
  OF 
  NEW 
  YORK 
  103 
  

  

  within 
  a 
  short 
  distance 
  of 
  the 
  Hudson 
  river, 
  this 
  being 
  the 
  area 
  

   classified 
  by 
  the 
  State 
  Weather 
  Bureau 
  under 
  the 
  names 
  of 
  the 
  

   Eastern 
  and 
  Western 
  plateaus. 
  The 
  streams 
  from 
  the 
  northern 
  

   crystalline 
  area 
  undoubtedly 
  furnish 
  the 
  best 
  water 
  supply 
  of 
  the 
  

   State. 
  This 
  is 
  probably 
  not 
  due 
  wholly 
  to 
  the 
  character 
  of 
  the 
  

   rocks, 
  as 
  many 
  other 
  factors 
  contribute 
  to 
  this 
  result. 
  

  

  The 
  sandstones 
  of 
  the 
  Upper 
  Devonian 
  along 
  the 
  northern 
  

   boundary 
  of 
  Pennsylvania 
  are 
  bounded 
  on 
  the 
  north 
  by 
  the 
  long 
  

   narrow 
  belts 
  of 
  outcrop 
  of 
  the 
  underlying 
  rocks 
  stretching 
  in 
  a 
  

   genera] 
  easterly 
  and 
  westerly 
  direction. 
  The 
  streams 
  pursuing 
  a 
  

   general 
  northerly 
  course 
  pass 
  in 
  succession 
  across 
  these. 
  As 
  a 
  

   rule, 
  the 
  soils 
  of 
  the 
  region 
  are 
  heavy, 
  with 
  considerable 
  clay, 
  and 
  

   the 
  rainfall 
  being 
  absorbed 
  somewhat 
  slowly, 
  a 
  considerable 
  por- 
  

   tion 
  of 
  it 
  flows 
  directly 
  into 
  the 
  watercourses. 
  The 
  primeval 
  

   forest 
  has 
  for 
  the 
  most 
  part 
  been 
  cut 
  away 
  and 
  heavy 
  floods 
  are 
  

   common, 
  such 
  as 
  those 
  of 
  the 
  Genesee 
  and 
  Chemung 
  rivers, 
  

   described 
  more 
  fully 
  on 
  a 
  later 
  page. 
  

  

  The 
  only 
  streams 
  of 
  this 
  region 
  on 
  which 
  extensive 
  discharge 
  

   measurements 
  have 
  been 
  made 
  are 
  the 
  Genesee 
  river 
  and 
  its 
  tribu- 
  

   tary, 
  Oatka 
  creek. 
  Streams 
  of 
  similar 
  character 
  in 
  western 
  Penn- 
  

   sylvania, 
  however, 
  have 
  been 
  measured 
  for 
  a 
  number 
  of 
  years 
  by 
  

   the 
  Philadelphia 
  Water 
  Department, 
  and 
  the 
  results 
  of 
  these 
  meas- 
  

   urements 
  are 
  available 
  for 
  comparison 
  and 
  discussion. 
  The 
  

   results 
  obtained 
  on 
  the 
  Pennsylvania 
  streams, 
  the 
  Neshaminy, 
  

   Tohickon 
  and 
  Perkiomen, 
  are 
  applicable 
  particularly 
  in 
  estimates 
  

   of 
  the 
  flow 
  of 
  the 
  tributaries 
  of 
  Delaware 
  river, 
  rising 
  in 
  New 
  

   York 
  State, 
  and 
  to 
  the 
  more 
  easterly 
  streams 
  which 
  form 
  the 
  

   Susquehanna. 
  

  

  The 
  catchment 
  basins 
  of 
  the 
  Oswego, 
  Mohawk 
  and 
  Hudson 
  

   rivers 
  are 
  so 
  highly 
  composite 
  as 
  regards 
  geologic 
  formations 
  and 
  

   embrace 
  such 
  a 
  wide 
  variation 
  in 
  topography 
  and 
  surface 
  geology 
  

   that 
  no 
  definite 
  deductions 
  concerning 
  the 
  effect 
  of 
  the 
  formations 
  

   on 
  water 
  flow 
  have 
  been 
  drawn. 
  The 
  streams 
  of 
  Long 
  Island, 
  

   rising 
  among 
  the 
  sands, 
  tills 
  and 
  gravels 
  of 
  comparatively 
  recent, 
  

   unconsolidated 
  formations, 
  offer 
  peculiar 
  conditions, 
  which 
  are 
  

   discussed 
  on 
  a 
  later 
  page. 
  

  

  