﻿28 
  Forty-seventh 
  Report 
  on 
  the 
  

  

  courses, 
  proportionate 
  to 
  its 
  relative 
  thickness 
  in 
  New 
  York. 
  The 
  

   courses 
  are 
  lettered 
  as 
  follows 
  : 
  

  

  No. 
  of 
  

   Cap 
  and 
  Top 
  Course, 
  Trap 
  and 
  Triassic 
  Sandstone. 
  courses. 
  

  

  Y. 
  Olean 
  Conglomerate 
  (Carboniferous) 
  1 
  

  

  Catskill 
  2 
  

  

  Portage 
  5 
  

  

  U. 
  Chemung 
  5 
  

  

  Genesee 
  , 
  1 
  

  

  Tully 
  1 
  

  

  T. 
  Hamilton 
  4 
  

  

  S. 
  Marcellus 
  1 
  

  

  R. 
  Upper 
  Helderberg, 
  or 
  Corniferous 
  2 
  

  

  P. 
  Schoharie 
  1 
  

  

  0. 
  Caudagalli 
  1 
  

  

  N. 
  Oriskany 
  < 
  ....... 
  . 
  1 
  

  

  M. 
  Lower 
  Helderberg. 
  , 
  2 
  

  

  L. 
  Salina 
  ' 
  4 
  

  

  K. 
  Niagara 
  2 
  

  

  J. 
  Clinton 
  1 
  

  

  1. 
  Medina 
  4 
  

  

  II. 
  Oneida 
  .... 
  1 
  

  

  G. 
  Hudson 
  River. 
  .• 
  5 
  

  

  F. 
  Trenton 
  1 
  

  

  E. 
  Chazy 
  1 
  

  

  D. 
  Calcif 
  erous 
  1 
  

  

  C. 
  Potsdam 
  1 
  

  

  B. 
  Acadian 
  . 
  * 
  2 
  

  

  A. 
  Georgia 
  6 
  

  

  Base, 
  Archaean 
  Granites 
  and 
  Gneisses. 
  

  

  Thanks 
  are 
  due 
  to 
  Prof. 
  William 
  B. 
  Dwight, 
  of 
  Yassar 
  College, 
  

   for 
  his 
  laborious 
  efforts 
  to 
  secure, 
  at 
  a 
  time 
  when 
  the 
  winter 
  

   weather 
  made 
  it 
  a 
  matter 
  of 
  great 
  difficulty, 
  stones 
  from 
  the 
  

   Cambrian 
  formation 
  of 
  Washington 
  county. 
  

  

  Several 
  propositions 
  were 
  made 
  to 
  secure 
  the 
  obelisk 
  for 
  edu- 
  

   cational 
  institutions, 
  but 
  the 
  board 
  of 
  managers 
  reserve 
  it 
  for 
  

   he 
  State. 
  

  

  Through 
  the 
  liberality 
  of 
  the 
  board 
  of 
  general 
  managers 
  of 
  

   the 
  State 
  of 
  New 
  York, 
  it 
  was 
  possible 
  to 
  install 
  and 
  arrange 
  this 
  

   ex] 
  libit 
  in 
  such 
  a 
  manner 
  that 
  it 
  received 
  high 
  praise 
  from 
  all 
  the 
  

   judges 
  detailed 
  to 
  examine 
  it. 
  

  

  