﻿HYDROLOGY 
  OF 
  NEW 
  YORK 
  481. 
  

  

  was 
  rather 
  low 
  August 
  23. 
  Hence, 
  Mohawk 
  flats 
  were 
  in 
  shape 
  

   to 
  absorb 
  a 
  considerable 
  portion 
  of 
  the 
  water 
  delivered 
  upon 
  them 
  

   into 
  the 
  interstices 
  below 
  the 
  surface. 
  Assuming, 
  as 
  already 
  

   stated, 
  30 
  square 
  miles 
  to 
  be 
  more 
  or 
  less 
  effected 
  by 
  such 
  an 
  in- 
  

   flow, 
  and 
  further 
  assuming 
  the 
  interstices 
  of 
  the 
  soil 
  of 
  this 
  30 
  

   square 
  miles 
  to 
  be 
  for 
  the 
  first 
  8 
  or 
  10 
  feet 
  of 
  depth 
  about 
  30 
  per 
  

   cent 
  to 
  40 
  per 
  cent 
  of 
  the 
  whole 
  volume, 
  we 
  reach 
  the 
  conclusion 
  

   that 
  the 
  temporary 
  storage 
  of 
  the 
  flats 
  may 
  have 
  been 
  as 
  much 
  

   as 
  3,000,000,000 
  to 
  4,000,000,000 
  cubic 
  feet, 
  which 
  sufficiently 
  ex- 
  

   plains 
  why 
  the 
  outgo 
  at 
  Little 
  Falls 
  did 
  not 
  exceed 
  12,000 
  to 
  

   14,000 
  cubic 
  feet 
  per 
  second. 
  

  

  The 
  foregoing 
  figures 
  do 
  not 
  take 
  into 
  account 
  the 
  extreme 
  maxi- 
  

   mums 
  which 
  may 
  be 
  expected 
  on 
  this 
  stream. 
  So 
  far 
  as 
  can 
  be 
  

   now 
  seen, 
  from 
  40,000 
  to 
  50,000 
  cubic 
  feet 
  per 
  second 
  delivery 
  

   into 
  the 
  flats 
  above 
  Little 
  Falls 
  is 
  rather 
  common. 
  The 
  extreme 
  

   maximum 
  must 
  be 
  considerably 
  greater 
  than 
  this. 
  Without 
  

   being 
  able 
  to 
  cite 
  specific 
  floods 
  proving 
  the 
  statement, 
  the 
  

   writer 
  is 
  nevertheless 
  disposed 
  to 
  say, 
  taking 
  into 
  account 
  the 
  

   known 
  maximum 
  floods 
  of 
  other 
  streams 
  of 
  the 
  State 
  — 
  Chemung, 
  

   Genesee 
  and 
  Croton 
  rivers 
  — 
  that 
  at 
  some 
  time 
  the 
  Mohawk 
  river 
  

   above 
  Little 
  Falls 
  may 
  yield 
  something 
  like 
  60,000 
  to 
  70,000 
  cubic 
  

   feet 
  per 
  second, 
  or 
  at 
  the 
  rate 
  of 
  perhaps 
  46 
  to 
  54 
  cubic 
  feet 
  per 
  

   second 
  per 
  square 
  mile. 
  

  

  A 
  study 
  of 
  the 
  flood-flows 
  of 
  the 
  Mohawk 
  river 
  would 
  be 
  incom- 
  

   plete 
  without 
  some 
  reference 
  to 
  the 
  surface 
  geology 
  of 
  the 
  catch- 
  

   ment 
  area. 
  The 
  main 
  trough 
  of 
  the 
  valley 
  lies 
  entirely 
  within 
  the 
  

   horizon 
  of 
  the 
  Hudson 
  river 
  and 
  Utica 
  shales, 
  where 
  the 
  soils, 
  aside 
  

   from 
  immediately 
  in 
  the 
  flat, 
  level 
  valley, 
  are 
  heavy 
  and 
  compact. 
  

   On 
  the 
  north 
  side, 
  beyond 
  the 
  horizon 
  of 
  the 
  shales, 
  Trenton 
  lime- 
  

   stone 
  and 
  calciferous 
  and 
  sand-rock 
  appear. 
  At 
  Little 
  Falls, 
  St 
  

   Johnsville 
  and 
  Amsterdam 
  these 
  formations 
  extend 
  down 
  into 
  the 
  

   valley 
  to 
  the 
  thread 
  of 
  the 
  stream. 
  To 
  the 
  north 
  of 
  the 
  Trenton 
  

   limestone 
  and 
  calciferous 
  sand-rock 
  the 
  Laurentian 
  granite 
  ap- 
  

   pears, 
  the 
  headwaters 
  of 
  West 
  and 
  East 
  Canada 
  creeks 
  lying 
  in 
  this 
  

   formation, 
  while 
  the 
  less 
  extended 
  streams 
  on 
  the 
  north 
  side 
  ter- 
  

   minate 
  either 
  in 
  the 
  shale 
  or 
  limestone 
  and 
  sand-rock 
  horizons. 
  

   In 
  the 
  vicinity 
  of 
  Fonda, 
  Johnstown, 
  Gloversville 
  and 
  Mayfield 
  

   the 
  shale 
  formations 
  extend 
  for 
  some 
  distance 
  to 
  the 
  north 
  of 
  the 
  

   trough 
  of 
  the 
  valley, 
  as 
  also 
  they 
  do 
  farther 
  east, 
  to 
  the 
  north 
  of 
  

   Schenectady. 
  

  

  