﻿76 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  Hill 
  conglomerate, 
  described 
  by 
  the 
  writer 
  from 
  the 
  neighborhood 
  

   of 
  Albany 
  (see 
  page 
  80). 
  

  

  This 
  belt 
  was 
  probably 
  first 
  noted 
  by 
  Emmons 
  who 
  indicated 
  

   it 
  on 
  his 
  map 
  accompanying 
  his 
  Agricultural 
  Report 
  1 
  and 
  gave 
  

   a 
  section 
  through 
  Bald 
  mountain 
  in 
  his 
  paper 
  on 
  the 
  Taconic 
  

   series 
  in 
  the 
  same 
  report. 
  He 
  identified 
  it 
  with 
  the 
  " 
  Calciferous 
  

   sandstone 
  " 
  (Beekmantown), 
  distinguishing 
  a 
  blue 
  portion 
  of 
  purer 
  

   limestone 
  and 
  a 
  lighter 
  one. 
  He 
  included, 
  however, 
  the 
  thin-bedded 
  

   limestone 
  on 
  top 
  of 
  the 
  mountain 
  in 
  the 
  " 
  Calciferous 
  sandrock." 
  

   This 
  latter 
  has 
  been 
  shown 
  by 
  Walcott 
  (op. 
  cit., 
  page 
  317) 
  to 
  be 
  of 
  

   Cambric 
  (Georgian) 
  age, 
  a 
  fault 
  separating 
  the 
  Georgian 
  rocks 
  from 
  

   the 
  limestone 
  belt 
  (see 
  chapter 
  on 
  structure 
  of 
  Bald 
  mountain, 
  page 
  

   108). 
  Walcott, 
  who 
  first 
  correctly 
  separated 
  on 
  a 
  map 
  the 
  Or- 
  

   dovicic 
  and 
  Lower 
  Cambric 
  areas 
  of 
  the 
  slate 
  belt 
  (op. 
  cit., 
  plate 
  3), 
  

   also 
  indicated 
  the 
  extension 
  of 
  the 
  limestone 
  belt 
  and 
  gave 
  a 
  section 
  

   of 
  Bald 
  mountain 
  in 
  which 
  he 
  distinguished 
  " 
  Calciferous 
  sand- 
  

   rock 
  " 
  (the 
  lower 
  darker 
  rock) 
  separated 
  by 
  dark 
  shales 
  from 
  

   " 
  Chazy 
  limestone." 
  From 
  a 
  locality 
  (op. 
  cit., 
  page 
  317) 
  about 
  2 
  

   miles 
  north 
  of 
  Bald 
  mountain, 
  Trenton 
  fossils 
  (Dalmanella 
  

   t 
  e 
  s 
  tud 
  i 
  n 
  a 
  r 
  i 
  a 
  , 
  Rafinesquina 
  alternata, 
  Mac- 
  

   lure 
  a 
  and 
  other 
  gastropods, 
  Calymmene 
  senaria 
  and 
  

   fragments 
  of 
  Asaphus 
  platycephalus) 
  are 
  cited. 
  It 
  is 
  

   thus 
  seen 
  that 
  Walcott 
  held 
  the 
  view 
  that 
  the 
  limestone 
  belt 
  contains 
  

   Calciferous, 
  Chazy 
  and 
  Trenton 
  rocks, 
  a 
  view 
  also 
  expressed 
  on 
  

   plate 
  3. 
  Dale 
  has 
  on 
  his 
  map 
  of 
  the 
  slate 
  belt 
  (1899, 
  plate 
  13) 
  dis- 
  

   tinguished 
  the 
  limestones 
  simply 
  as 
  lower 
  Siluric 
  (Ordovicic) 
  lime- 
  

   stone 
  from 
  the 
  Lower 
  Siluric 
  shale, 
  etc., 
  stating 
  (page 
  190) 
  : 
  " 
  The 
  

   Trenton 
  limestone 
  occurs 
  sporadically 
  within 
  the 
  Ordovician 
  areas 
  

   of 
  the 
  slate 
  belt; 
  also 
  on 
  its 
  western 
  edge 
  in 
  Argyle 
  and 
  in 
  Hart- 
  

   ford. 
  In 
  some 
  places 
  it 
  was 
  probably 
  deposited 
  contemporaneously 
  

   with 
  the 
  Hudson 
  grit 
  and 
  shales, 
  or 
  it 
  may 
  underlie 
  a 
  portion 
  of 
  

   them. 
  In 
  others 
  it 
  may 
  represent 
  the 
  entire 
  Lower 
  Silurian 
  series 
  

   and 
  should 
  then 
  be 
  regarded 
  as 
  Trenton, 
  Chazy 
  and 
  Calciferous." 
  

  

  We 
  see 
  from 
  this 
  quotation 
  that 
  the 
  determinations 
  of 
  the 
  age 
  of 
  

   the 
  Ordovicic 
  limestone 
  in 
  the 
  slate 
  belt 
  are 
  rather 
  insecure, 
  a 
  fact 
  

   that 
  can 
  be 
  readily 
  explained 
  by 
  the 
  scarcity 
  and 
  poor 
  preservation 
  

   of 
  the 
  fossils 
  usually 
  obtained 
  there. 
  

  

  On 
  the 
  Geologic 
  Map 
  of 
  New 
  York, 
  published 
  by 
  F. 
  J. 
  H. 
  Mer- 
  

   rill 
  (1901), 
  the 
  limestone 
  belt 
  on 
  the 
  west 
  edge 
  of 
  the 
  Georgian 
  is 
  

   entered 
  simply 
  as 
  Trenton. 
  

  

  1 
  Emmons, 
  Ebenezer. 
  Agriculture 
  of 
  New 
  York, 
  v. 
  1, 
  1846. 
  

  

  