﻿110 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  In 
  the 
  following 
  pages 
  the 
  geneFal 
  arrangement 
  is 
  similar 
  to 
  

   that 
  adopted 
  in 
  moist 
  of 
  the 
  geologic 
  text 
  books. 
  The 
  introduc- 
  

   tory 
  matter 
  is 
  newly 
  written 
  and 
  also 
  the 
  larger 
  portion 
  of 
  the 
  

   chapters 
  on 
  the 
  Archaean 
  and 
  Cambrian 
  rocks. 
  The 
  Cambrian 
  

   below 
  the 
  Potsdam 
  was 
  not 
  known 
  as 
  such 
  in 
  Lincklaen's 
  time 
  

   and 
  was 
  not 
  discussed 
  by 
  him. 
  The 
  description 
  given 
  herewith 
  is 
  

   taken 
  chiefly 
  from 
  the 
  work 
  of 
  C. 
  D. 
  Walcott, 
  Bulletin 
  of 
  the 
  

   U. 
  S. 
  Geological 
  Survey 
  No. 
  81. 
  The 
  Palaeozoic 
  strata 
  of 
  New 
  

   York 
  from 
  the 
  Potsdam 
  to 
  the 
  Catskill 
  were 
  well 
  known 
  to 
  the 
  

   members 
  of 
  the 
  original 
  geological 
  corps, 
  Hall, 
  Mather, 
  Emmons^ 
  

   and 
  Vanuxem 
  and 
  Lincklaen's 
  interpretations 
  of 
  their 
  published 
  

   results 
  were 
  so 
  satisfactory 
  that 
  in 
  the 
  present 
  work 
  his 
  descrip- 
  

   tions 
  of 
  these 
  formations 
  have 
  been 
  used, 
  so 
  far 
  as 
  practicable,, 
  

   with 
  such 
  corrections 
  and 
  additions 
  as 
  were 
  necessary 
  to 
  express 
  

   our 
  present 
  knowledge. 
  

  

  In 
  making 
  these 
  corrections, 
  the 
  statements 
  of 
  the 
  original 
  

   corps 
  of 
  geologists 
  and 
  of 
  the 
  later 
  geologists 
  who 
  have 
  worked, 
  

   in 
  New 
  York 
  have 
  been 
  freely 
  quoted. 
  

  

  The 
  descriptions 
  of 
  the 
  Mesozoic 
  and 
  Cenozoic 
  ages 
  have 
  been 
  

   newly 
  written. 
  

  

  Lincklaen's 
  descriptions 
  of 
  the 
  fossils 
  of 
  New 
  York 
  are 
  not 
  

   wholly 
  accurate 
  in 
  the 
  light 
  of 
  modern 
  knowledge 
  and 
  in 
  order 
  

   to 
  save 
  time 
  in 
  revision 
  and 
  the 
  considerable 
  space 
  needed 
  for 
  a 
  

   proper 
  presentation 
  of 
  the 
  subject, 
  they 
  have 
  been 
  omitted. 
  Kef- 
  

   erences 
  are, 
  however, 
  given 
  to 
  the 
  proper 
  authorities 
  and 
  it 
  is 
  

   hoped 
  that 
  the 
  State 
  Palaeontologist 
  may 
  prepare 
  a 
  handbook 
  on 
  

   this 
  important 
  subject. 
  

  

  The 
  chapter 
  on 
  economic 
  geology 
  is 
  abridged 
  from 
  Bulletin 
  15 
  

   of 
  the 
  New 
  York 
  State 
  Museum, 
  with 
  some 
  additions. 
  

  

  The 
  illustrations 
  are, 
  to 
  a 
  large 
  extent, 
  new 
  and 
  it 
  is 
  believed 
  

   that 
  the 
  representation 
  of 
  typical 
  sections 
  and 
  exposures 
  by 
  

   photographs 
  is 
  more 
  satisfactory 
  than 
  by 
  the 
  more 
  common 
  dia- 
  

   grams. 
  

  

  It 
  is 
  to 
  be 
  regretted 
  that 
  it 
  was 
  not 
  possible 
  to 
  make 
  a 
  series 
  

   of 
  photographs 
  complete 
  in 
  each 
  geologic 
  series, 
  but 
  no 
  opportun- 
  

  

  