﻿448 
  Forty-seventh 
  Report 
  on 
  the 
  State 
  Museum. 
  

  

  west 
  to 
  east, 
  as 
  it 
  extends 
  southward, 
  along 
  axes 
  striking 
  south 
  

   ten 
  degrees 
  west, 
  approximately, 
  and 
  pitching 
  slightly 
  in 
  the 
  

   same 
  direction, 
  which 
  is 
  diagonal 
  to 
  the 
  general 
  inclination 
  of 
  

   the 
  monocline. 
  In 
  figures 
  4 
  and 
  5 
  I 
  have 
  attempted 
  to 
  illustrate 
  

   the 
  nature 
  of 
  these 
  features 
  in 
  the 
  limestone 
  area, 
  for 
  they 
  are 
  

   an 
  interesting 
  example 
  of 
  the 
  beginning 
  of 
  the 
  series 
  of 
  flexures, 
  

   and 
  they 
  explain 
  the 
  singular 
  distribution 
  of 
  the 
  Helderberg 
  

   rocks 
  in 
  this 
  portion 
  of 
  Albany 
  county. 
  

  

  

  

  1 
  — 
  \ 
  o 
  

   E3^ 
  ft 
  

  

  

  o 
  

  

  &s*_ 
  

  

  

  

  

  T 
  

   ft 
  

  

  

  

  

  " 
  

  

  -»-Si 
  

  

  

  

  SZ2 
  

  

  

  Piq.5 
  

  

  Fig. 
  5.— 
  Cross 
  section 
  oa 
  Hue 
  A.- 
  A 
  in 
  figure 
  4. 
  From 
  north 
  of 
  South 
  Bethlehem 
  through 
  

   Copeland 
  hill. 
  Vertical 
  scale, 
  two 
  and 
  one-half 
  times 
  the 
  horizontal 
  scale. 
  H., 
  Hamilton; 
  

   On., 
  Onondaga 
  limestone; 
  CO., 
  Esopus 
  shales; 
  O., 
  Oriskaiiy: 
  S.. 
  Becraft 
  limestone; 
  SI 
  , 
  Shaly 
  

   limestone; 
  P., 
  Pentamerus 
  limestone; 
  T 
  , 
  Tentaculite 
  beds 
  and 
  Salina 
  waterlime; 
  SL., 
  Position 
  

   of 
  sea 
  level. 
  Looking 
  north. 
  

  

  It 
  will 
  be 
  seen 
  in 
  these 
  figures 
  that 
  the 
  undulations 
  increase 
  in 
  

   steepness 
  to 
  the 
  eastward 
  and 
  finally 
  become 
  a 
  succession 
  of 
  

   steep 
  parallel 
  folds 
  which 
  are 
  of 
  true 
  Appalachian 
  type. 
  

  

  In 
  plate 
  5 
  there 
  is 
  shown 
  the 
  structure 
  of 
  the 
  flexed 
  region 
  in 
  

   the 
  southeastern 
  corner 
  of 
  the 
  county 
  and 
  for 
  a 
  couple 
  of 
  miles 
  

   southward. 
  

  

  In 
  this 
  plate 
  there 
  should 
  be 
  noticed 
  the 
  distinct 
  topographical 
  

   characteristics 
  of 
  the 
  several 
  formations 
  of 
  the 
  Helderberg 
  and 
  

   overlying 
  formations. 
  The 
  steep 
  slope 
  or 
  scarp 
  of 
  the 
  Pentam- 
  

   erus 
  bed 
  is 
  sharply 
  defined 
  except 
  at 
  the 
  Hannacrois 
  creek, 
  

   where 
  it 
  is 
  broken 
  across 
  ; 
  but 
  it 
  gives 
  rise 
  to 
  falls 
  of 
  consider- 
  

   able 
  amount 
  in 
  the 
  creek, 
  with 
  a 
  deep 
  gorge 
  for 
  some 
  distance 
  

   below. 
  The 
  Esopus 
  shales 
  constitute 
  sharp 
  ridges 
  and 
  the 
  Onon- 
  

   daga 
  limestone 
  is 
  marked 
  by 
  a 
  well-defined 
  shelf, 
  which 
  expands 
  

   to 
  great 
  width 
  in 
  the 
  Hannacrois 
  valley. 
  The 
  Hamilton 
  shales 
  

   rise 
  abruptly 
  into 
  high, 
  irregular 
  hills 
  of 
  typical 
  character. 
  In 
  

   the 
  northern 
  section 
  on 
  plate 
  5 
  the 
  flexures 
  are 
  steep 
  and 
  involve 
  

   the 
  Helderberg 
  and 
  overlying 
  rocks 
  over 
  a 
  belt 
  of 
  considerable 
  

   width. 
  The 
  steepness 
  of 
  the 
  cliffs 
  decreases 
  southward 
  for 
  some 
  

   distance, 
  and 
  near 
  the 
  second 
  section 
  there 
  is 
  a 
  succession 
  of 
  

  

  