﻿IC'8 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  one 
  passes 
  in 
  the 
  Hudson 
  River 
  plain 
  over 
  Snake 
  Hill 
  shales, 
  fre- 
  

   quently 
  covered 
  by 
  quaternary 
  clays, 
  until 
  near 
  the 
  foot 
  of 
  the 
  

   hills 
  marking 
  the 
  edge 
  of 
  the 
  Greenwich 
  plateau. 
  Here 
  there 
  is 
  

   a 
  belt 
  of 
  much 
  broken 
  and 
  distorted 
  Beekmantown 
  limestone 
  (Bald 
  

   Mountain 
  limestone) 
  and 
  coarse 
  conglomerate 
  (Rysedorph 
  Hill 
  

   conglomerate), 
  and 
  the 
  hills 
  themselves 
  and 
  the 
  plateau 
  behind 
  

   them 
  consist 
  of 
  the 
  Georgian 
  rocks. 
  The 
  latter, 
  although 
  im- 
  

   mensely 
  older, 
  hold 
  a 
  higher 
  level 
  than 
  the 
  shales 
  west 
  of 
  them. 
  

   The 
  explanation 
  of 
  this 
  remarkable 
  fact 
  is 
  that 
  the 
  Georgian 
  

   has 
  been 
  overthrust 
  upon 
  the 
  Ordovicic 
  rocks. 
  This 
  is 
  most 
  

   clearly 
  shown 
  at 
  Bald 
  mountain 
  where 
  the 
  former 
  quarrying 
  of 
  

   the 
  limestone 
  at 
  the 
  foot 
  of 
  the 
  mountain 
  has 
  opened 
  a 
  splendid 
  

   section 
  (see 
  plate 
  of 
  sections). 
  

  

  Bald 
  mountain 
  is, 
  geologically 
  speaking, 
  an 
  historical 
  mountain. 
  

   It 
  has 
  played 
  a 
  conspicuous 
  role 
  in 
  the 
  Taconic 
  controversy 
  and 
  

   it 
  is 
  therefore 
  proper 
  in 
  this 
  place 
  briefly 
  to 
  review 
  its 
  history. 
  

   Emmons 
  was 
  the 
  first 
  to 
  direct 
  attention 
  to 
  the 
  Bald 
  Mountain 
  

   section 
  as 
  being 
  an 
  interesting 
  example 
  in 
  the 
  relative 
  position 
  of 
  

   the 
  "Taconic" 
  and 
  " 
  Champlainic 
  " 
  (Ordovicic) 
  rocks, 
  that 
  is, 
  as 
  

   showing 
  the 
  Champlainic 
  rocks 
  as 
  resting 
  unconformably 
  on 
  the 
  

   Taconic 
  rocks. 
  He 
  gave 
  (1846, 
  page 
  89) 
  a 
  section 
  through 
  Bald 
  

   mountain 
  showing 
  the 
  " 
  calcif 
  erous 
  sandstone 
  " 
  extending 
  from 
  

   the 
  top 
  of 
  the 
  mountain 
  to 
  the 
  western 
  foot 
  where 
  it 
  is 
  underlain 
  

   by 
  the 
  " 
  Taconic 
  " 
  black 
  slates, 
  which 
  also 
  appear 
  on 
  the 
  eastern 
  

   foot 
  of 
  the 
  mountain. 
  The 
  two 
  trilobites 
  At 
  ops 
  trilineatus 
  

   and 
  Elliptocephala 
  asaphoides, 
  which 
  demonstrated 
  

   the 
  actual 
  presence 
  of 
  rocks 
  older 
  than 
  Potsdam 
  in 
  the 
  slate 
  belt, 
  

   were 
  also 
  cited 
  as 
  coming 
  from 
  the 
  strata 
  " 
  near 
  Bald 
  mountain 
  " 
  1 
  

   (op. 
  cit., 
  page 
  63). 
  

  

  Walcott 
  (op. 
  cit., 
  page 
  317) 
  has 
  shown 
  that 
  the 
  complex 
  struc- 
  

   tural 
  relations 
  of 
  Bald 
  mountain 
  are 
  entirely 
  different 
  from 
  what 
  

   Emmons 
  supposed 
  them 
  to 
  be. 
  He 
  found 
  Georgian 
  fossils 
  in 
  the 
  

   limestones, 
  forming 
  the 
  summit 
  of 
  the 
  mountain, 
  and 
  states 
  : 
  

   " 
  Doctor 
  Emmons 
  identified 
  this 
  mass 
  of 
  strata, 
  d, 
  with 
  the 
  cal- 
  

   ciferous 
  sandrock 
  on 
  lithologic 
  characters, 
  overlooking 
  the 
  fact 
  

   that 
  a 
  similar 
  rock 
  might 
  occur 
  in 
  his 
  Taconic 
  series." 
  Walcott 
  

   also 
  recognized 
  the 
  overthrust 
  at 
  Bald 
  mountain. 
  He 
  says 
  : 
  " 
  The 
  

   section 
  of 
  Bald 
  mountain 
  proves 
  that 
  the 
  strata 
  of 
  the 
  ' 
  Upper 
  

  

  1 
  Walcott 
  {op. 
  cit., 
  p. 
  326) 
  cites 
  them 
  as 
  coming 
  from 
  the 
  black 
  slate 
  2 
  miles 
  

   north 
  of 
  Bald 
  mountain, 
  where 
  Doctor 
  Fitch 
  found 
  them. 
  

  

  