﻿GEOLOGIC 
  FORMATIONS 
  OF 
  NEW 
  YOKK 
  141 
  

  

  The 
  principal 
  group 
  of 
  mountains, 
  which 
  includes 
  Mt 
  Marcy, 
  is 
  

   of 
  massive 
  roicks 
  known 
  as 
  norite 
  and 
  anorthosite. 
  The 
  pre- 
  

   vailing 
  rocks 
  of 
  the 
  wilderness 
  are, 
  however, 
  gneisses 
  of 
  different 
  

   kinds. 
  In 
  these 
  are 
  many 
  local 
  intrusions 
  of 
  granite 
  and 
  other 
  

   eruptives. 
  Trap, 
  serpentine 
  and 
  many 
  other 
  rocks 
  of 
  igneous 
  

   origin 
  are 
  found 
  in 
  all 
  parts 
  of 
  the 
  district. 
  The 
  great 
  route 
  of 
  

   travel 
  through 
  Lakes 
  George 
  and 
  Champlain 
  is 
  bordered 
  by 
  

   mountains 
  and 
  cliffs, 
  in 
  which 
  these 
  rocks 
  are 
  seen 
  in 
  great 
  

   variety. 
  

  

  In 
  the 
  Mohawk 
  valley 
  are 
  small 
  exposures 
  of 
  pre-Cambrian, 
  at 
  

   Littlefalls 
  and 
  near 
  Spraker's. 
  These 
  are 
  important 
  localities 
  

   and 
  show 
  the 
  relations 
  of 
  the 
  over-lying 
  Palaeozoic 
  rocks. 
  

  

  Proterozoic 
  or 
  Agxotozoic 
  

  

  Eocks 
  of 
  this 
  age 
  are 
  not 
  definitely 
  known 
  in 
  New 
  York. 
  They 
  

   are 
  well 
  represented 
  in 
  the 
  Lake 
  Superior 
  region 
  by 
  those 
  forma- 
  

   tions 
  known 
  as 
  Huronian 
  and 
  the 
  copper 
  bearing 
  deposits 
  of 
  the 
  

   Keeweenaw 
  peninsula. 
  West 
  of 
  the 
  Eocky 
  mountains, 
  they 
  are 
  

   developed 
  extensively. 
  All 
  rocks 
  between 
  the 
  Archaean 
  and 
  the 
  

   Cambrian 
  are 
  included. 
  

  

  Palaeozoic 
  

  

  Upon 
  the 
  plutonic 
  and 
  metamorphic 
  rocks 
  of 
  the 
  Archaean 
  

   in 
  New 
  York 
  rest 
  directly 
  the 
  Palaeozoic 
  strata 
  which 
  are 
  all 
  

   fossil-bearing 
  rocks. 
  The 
  Palaeozoic 
  series 
  includes 
  all 
  strata 
  

   from 
  the 
  base 
  of 
  the 
  Cambrian 
  to 
  the 
  summit 
  of 
  the 
  Carbonif- 
  

   erous. 
  

  

  These 
  stratified 
  fossil-bearing 
  rocks 
  form 
  the 
  greater 
  part 
  of 
  

   the 
  state 
  of 
  New 
  York. 
  

  

  At 
  the 
  beginning 
  of 
  the 
  Palaeozoic, 
  all 
  life 
  was 
  marine, 
  prob- 
  

   ably 
  because 
  the 
  land 
  surfaces 
  were 
  at 
  first 
  too 
  small 
  to 
  materi- 
  

   ally 
  influence 
  the 
  evolution 
  of 
  living 
  forms. 
  In 
  the 
  Cambrian, 
  

   crustaceans 
  prevailed, 
  in 
  the 
  Lower 
  Silurian 
  the 
  Cephalopods 
  or 
  

   cuttle 
  fishes, 
  in 
  the 
  Devonian 
  the 
  soft 
  boned 
  fishes 
  were 
  the 
  

   dominant 
  type, 
  while 
  in 
  the 
  Carboniferous, 
  fishes 
  and 
  amphibians 
  

   divided 
  the 
  honors 
  of 
  the 
  sea 
  and 
  the 
  land. 
  

  

  