﻿GEOLOGY 
  OF 
  THE 
  PORT 
  LEYDEN 
  QUADIL\NGLE 
  

  

  29 
  

  

  within 
  the 
  quadrangle. 
  In 
  a 
  general 
  way 
  the 
  Trenton 
  here 
  shows 
  

   most 
  of 
  the 
  features 
  of 
  the 
  type 
  locality. 
  At 
  Trenton 
  Falls 
  the 
  

   formation 
  is 
  about 
  300 
  feet 
  thick 
  and 
  the 
  rocks 
  are 
  mostly 
  thin 
  

   bedded, 
  impure, 
  dark 
  limestones 
  with 
  pronounced 
  shale 
  partings, 
  

   except 
  the 
  upper 
  30 
  feet 
  which 
  are 
  thicker 
  bedded, 
  gray, 
  crystalline 
  

   limestones. 
  The 
  following 
  section 
  shows 
  that 
  a 
  marked 
  lithologic 
  

   change 
  has 
  taken 
  place 
  in 
  passing 
  from 
  Trenton 
  Falls 
  to 
  Port 
  

   Leyden. 
  

  

  ■L'» 
  I 
  

  

  i— 
  i 
  

  

  Thick 
  bedded, 
  coarse 
  crystalline, 
  gray 
  limestone 
  

  

  Fairly 
  thick 
  bedded, 
  gray, 
  crystalline 
  limestone 
  

  

  Very 
  thin 
  bedded, 
  dark 
  limestone 
  with 
  thin 
  shale 
  

   partings 
  

  

  Thick 
  bedded, 
  coarse 
  crystalline, 
  gray 
  limestone 
  

   Fairly 
  thick 
  bedded 
  crystalline, 
  gray 
  limestone 
  

  

  Thin 
  bedded, 
  dark 
  limestone 
  with 
  thin 
  shale 
  partings 
  

  

  Thick, 
  gray, 
  crystalline 
  limestone 
  beds 
  

  

  Alternating, 
  thin 
  bedded, 
  black 
  limestone 
  and 
  shale 
  

  

  Fig. 
  I 
  Columnar 
  section 
  from 
  base 
  to 
  summit 
  of 
  the 
  Trenton 
  limestone 
  formation 
  along 
  

   Sugar 
  river 
  and 
  Moose 
  creek. 
  The 
  section 
  is 
  350 
  feet 
  thick. 
  

  

  More 
  than 
  half 
  of 
  the 
  section 
  is 
  here 
  made 
  up 
  of 
  the 
  gray, 
  

   crystalline, 
  heavy 
  beds 
  as 
  opposed 
  to 
  only 
  about 
  30 
  feet 
  of 
  such 
  

   beds 
  at 
  Trenton 
  Falls. 
  Within 
  the 
  Little 
  Falls 
  quadrangle 
  the 
  

   heavy, 
  crystalline 
  beds 
  are 
  absent 
  altogether, 
  the 
  upper 
  Trenton 
  

   being 
  represented 
  by 
  the 
  Dolgeville 
  shales 
  which 
  are 
  in 
  reality 
  

   alternating 
  thin 
  beds 
  of 
  impure 
  limestone 
  and 
  shales. 
  These 
  and 
  

  

  