﻿FIFTH 
  REPORT 
  OF 
  THE 
  DIRECTOR 
  I908 
  II 
  5 
  

  

  ONE 
  HUNDRED 
  YEARS 
  OF 
  NEW 
  YORK 
  STATE 
  

   GEOLOGIC 
  MAPS 
  1809-1909 
  

  

  BY 
  HENRY 
  LEIGHTON 
  

  

  In 
  geology 
  as 
  in 
  other 
  sciences, 
  no 
  satisfactory 
  understanding 
  of 
  

   the 
  subject 
  can 
  be 
  acquired 
  without 
  a 
  knowledge 
  of 
  the 
  history 
  of 
  

   its 
  development. 
  As 
  Geikie 
  says 
  " 
  it 
  is 
  eminently 
  useful, 
  now 
  and 
  

   then, 
  to 
  pause 
  in 
  the 
  race, 
  and 
  to 
  look 
  backward 
  over 
  the 
  ground 
  

   that 
  has 
  been 
  traversed, 
  to 
  mark 
  the 
  errors 
  as 
  well 
  as 
  the 
  successes 
  

   of 
  the 
  journey." 
  

  

  We 
  have 
  thought 
  it 
  of 
  interest 
  to 
  review 
  briefly 
  the 
  development 
  

   of 
  geology 
  in 
  New 
  York 
  State 
  as 
  evidenced 
  by 
  the 
  published 
  maps, 
  

   and 
  to 
  publish 
  a 
  list 
  of 
  such 
  maps 
  arranged 
  in 
  chronological 
  order 
  

   and 
  indexed 
  ; 
  this 
  list 
  not 
  only 
  to 
  serve 
  as 
  a 
  reference 
  index 
  to 
  all 
  

   geological 
  maps 
  of 
  the 
  State 
  but, 
  as 
  well, 
  to 
  show 
  briefly 
  the 
  devel- 
  

   opment 
  of 
  the 
  science 
  of 
  geolog}^- 
  in 
  the 
  State. 
  

  

  For 
  the 
  clear 
  interpretation 
  of 
  the 
  geology 
  of 
  a 
  region, 
  both 
  in 
  

   the 
  distribution 
  and 
  structural 
  features 
  of 
  its 
  rocks, 
  geologic 
  maps 
  

   are 
  almost 
  indispensable 
  as 
  an 
  accompaniment 
  to 
  a 
  written 
  descrip- 
  

   tion. 
  This 
  fact 
  was 
  comprehended 
  by 
  the 
  very 
  early 
  observers, 
  and 
  

   even 
  before 
  geology 
  as 
  a 
  science 
  was. 
  recognized, 
  geologic 
  or, 
  more 
  

   correctly, 
  mineralogic 
  maps 
  were 
  drawn. 
  By 
  all 
  writers 
  the 
  credit 
  

   for 
  the 
  publication 
  of 
  the 
  first 
  map 
  showing 
  geological 
  features 
  has 
  

   been 
  given 
  to 
  Jean 
  Etienne 
  Guettard 
  who 
  in 
  1751^ 
  issued 
  a 
  map 
  

   of 
  Paris 
  and 
  its 
  environs. 
  This 
  was 
  more 
  of 
  a 
  mineralogic 
  than 
  a 
  

   geologic 
  map, 
  its 
  author 
  seemingly 
  having 
  no 
  conception 
  of 
  geologi- 
  

   cal 
  structure 
  or 
  sequence 
  of 
  formations. 
  Guettard, 
  unlike 
  many 
  

   scientists 
  of 
  his 
  time 
  and 
  many 
  more 
  following 
  him, 
  was 
  not 
  of 
  a 
  

   speculative 
  turn 
  of 
  mind, 
  but 
  believed 
  strongly 
  in 
  observation 
  as 
  

   the 
  best 
  means 
  of 
  deriving 
  important 
  scientific 
  truths. 
  Originally 
  

   a 
  botanist, 
  in 
  his 
  botanical 
  excursions 
  he 
  became 
  interested 
  in 
  the 
  

   minerals 
  and 
  fossils 
  he 
  came 
  across, 
  and 
  soon 
  became 
  convinced 
  of 
  

   the 
  fact 
  that 
  minerals 
  and 
  fossils 
  were 
  not 
  promiscuously 
  distributed 
  

   over 
  and 
  through 
  the 
  rocks 
  but 
  were 
  arranged 
  in 
  definite 
  bands. 
  

  

  He 
  then 
  conceived 
  the 
  idea- 
  of 
  fixing 
  his 
  observations 
  by 
  the 
  use 
  

   of 
  a 
  map 
  showing 
  the 
  mineral 
  and 
  fossil 
  localities, 
  which 
  were 
  indi- 
  

  

  ^ 
  Mem. 
  Acad. 
  Roy. 
  Sciences, 
  France. 
  1751. 
  

  

  ^ 
  A 
  similar 
  plan, 
  although 
  probably 
  unknown 
  to 
  Guettard, 
  was 
  proposed 
  

   in 
  a 
  paper 
  presented 
  before 
  the 
  Royal 
  Society 
  of 
  London 
  in 
  1683. 
  

  

  