﻿290 
  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1927 
  

  

  are 
  unusual, 
  exceptional, 
  and 
  transitory. 
  Excepting 
  the 
  peculiar 
  

   ones 
  in 
  Florida 
  and 
  on 
  the 
  Mississippi 
  delta 
  there 
  are 
  few 
  lakes 
  

   to-day 
  in 
  America, 
  out,side 
  of 
  glaciated 
  territory. 
  The 
  oxbows 
  in 
  the 
  

   flood 
  plains 
  of 
  rivers 
  are 
  not 
  counted. 
  

  

  Most 
  lakes 
  may 
  be 
  defined 
  as 
  expansions 
  of 
  streams. 
  But 
  the 
  

   basins 
  or 
  reservoirs 
  are 
  not 
  made 
  by 
  the 
  streams 
  in 
  normal 
  flow. 
  

   Some 
  external 
  interference 
  or 
  damming 
  effect 
  is 
  necessary. 
  Streams 
  

   can 
  not 
  permanently 
  dam 
  themselves. 
  Ice 
  jams, 
  log 
  jams, 
  and 
  land- 
  

   slides 
  make 
  temporary 
  reservoirs. 
  The 
  singular 
  and 
  beautiful 
  lake- 
  

   lets 
  near 
  Syracuse, 
  one 
  in 
  a 
  State 
  park, 
  occupy 
  cataract 
  plunge- 
  

   basins 
  and 
  are 
  of 
  very 
  exceptional 
  and 
  interesting 
  character. 
  With 
  

   their 
  bounding 
  cliffs 
  they 
  are 
  fossil 
  Niagaras. 
  To-day 
  Niagara 
  Falls 
  

   is 
  drilling 
  a 
  similar 
  bowl. 
  The 
  Syracuse 
  Basin,s 
  were 
  carved 
  by 
  

   rivers 
  which 
  in 
  function 
  were 
  true 
  predecessors 
  of 
  Niagara. 
  They 
  

   were 
  held 
  up 
  in 
  forced 
  flow 
  by 
  the 
  front 
  of 
  the 
  waning 
  glacier. 
  

   Perhaps 
  they 
  are 
  the 
  best 
  example 
  of 
  streams 
  making 
  basins. 
  But 
  

   these 
  lakelets 
  did 
  not 
  exist 
  while 
  the 
  rivers 
  were 
  flowing. 
  

  

  In 
  regions 
  of 
  land 
  movement, 
  a,s 
  mountain 
  districts, 
  basins 
  are 
  

   sometimes 
  produced 
  by 
  the 
  bending 
  and 
  the 
  breaking 
  of 
  the 
  earth's 
  

   crust. 
  The 
  Jordan 
  Valley 
  and 
  Dead 
  Sea 
  are 
  examples 
  of 
  the 
  latter. 
  

   The 
  basin 
  of 
  Lake 
  Superior 
  is 
  thought 
  to 
  be 
  due 
  in 
  part 
  to 
  crustal 
  

   warping. 
  But 
  the 
  basins 
  of 
  the 
  Finger 
  Lakes 
  are 
  in 
  practically 
  hori- 
  

   zontal 
  strata, 
  lifted 
  out 
  of 
  the 
  sea 
  and 
  without 
  serious 
  deformation. 
  

  

  A,s 
  reckoned 
  in 
  geologic 
  time, 
  lakes 
  are 
  short-lived. 
  They 
  dis- 
  

   appear 
  either 
  by 
  the 
  downcutting 
  of 
  their 
  outlets 
  or 
  by 
  the 
  filling 
  of 
  

   their 
  basins. 
  Sand 
  and 
  silt 
  are 
  swept 
  in 
  by 
  streams 
  and 
  by 
  winds 
  in 
  

   arid 
  regions, 
  and 
  vegetable 
  growth 
  assists 
  the 
  filling 
  process. 
  Shal- 
  

   low 
  lakes 
  which 
  recently 
  existed 
  in 
  some 
  of 
  the 
  New 
  York 
  valleys 
  

   have 
  already 
  become 
  plain,s 
  or 
  swamps. 
  The 
  extensive 
  plains 
  at 
  the 
  

   heads 
  of 
  the 
  Finger 
  Lakes, 
  Seneca 
  and 
  Cayuga, 
  for 
  example, 
  show 
  

   the 
  rapid 
  filling 
  by 
  the 
  detritus 
  swept 
  in 
  by 
  the 
  inlet 
  streams. 
  

  

  The 
  scores 
  of 
  thousaiKls 
  of 
  lakes 
  and 
  lakelets 
  in 
  our 
  Northern 
  States 
  

   and 
  Canada 
  came 
  into 
  very 
  recent 
  existence 
  with 
  the 
  melting 
  away 
  of 
  

   the 
  Canadian 
  ice 
  sheets. 
  Previous 
  to 
  the 
  glacial 
  invasions 
  there 
  were 
  

   few, 
  if 
  any, 
  lakes 
  in 
  eastern 
  America. 
  This 
  implies 
  that 
  the 
  Finger 
  

   Lakes 
  are 
  not 
  old. 
  Indeed, 
  they 
  are 
  very 
  j^oung, 
  speaking 
  in 
  geologic 
  

   lingo. 
  Their 
  life 
  is 
  reckoned 
  only 
  in 
  tens, 
  or 
  at 
  most, 
  in 
  scores 
  of 
  

   thousands 
  of 
  years. 
  But 
  the 
  valleys 
  in 
  which 
  they 
  lie 
  have 
  been 
  in 
  

   tlie 
  making 
  for 
  uncounted 
  millions 
  of 
  years. 
  The 
  Finger 
  Lakes 
  are 
  

   about 
  the 
  latest 
  geologic 
  features 
  in 
  the 
  State. 
  The 
  cataracts 
  and 
  

   canyons 
  are 
  younger. 
  Lake 
  Ontario 
  is 
  the 
  youngest 
  great 
  physio- 
  

   graphic 
  feature 
  in 
  America. 
  

  

  The 
  origin 
  of 
  the 
  parallel 
  valleys 
  must 
  first 
  be 
  learned, 
  and 
  then 
  

   how 
  they 
  came 
  to 
  be 
  dammed. 
  This 
  series 
  of 
  parallel 
  valleys 
  is 
  

  

  