﻿Report 
  of 
  the 
  State 
  Geologist. 
  551 
  

  

  No 
  shales 
  were 
  observed 
  in 
  places 
  in 
  the 
  depression, 
  but 
  a 
  small 
  

   amount 
  of 
  shale 
  debris 
  was 
  noticed 
  at 
  one 
  point. 
  Everywhere 
  

   along 
  the 
  steep 
  slopes 
  there 
  are 
  clefts 
  in 
  the 
  grit, 
  so 
  Tie 
  of 
  which 
  

   appear 
  to 
  extend 
  down 
  to 
  the 
  shales. 
  One 
  of 
  these 
  is 
  the 
  "Ice 
  

   Cave," 
  a 
  locality 
  which 
  is 
  widely 
  famous 
  in 
  the 
  region. 
  It 
  is 
  high 
  

   in 
  the 
  slope 
  about 
  two 
  miles 
  east-northeast 
  of 
  Ellenville. 
  Ice 
  and 
  

   snow 
  remain 
  in 
  it 
  in 
  greater 
  or 
  less 
  amount 
  and 
  in 
  some 
  seasons 
  

   are 
  preserved 
  entirely 
  through 
  the 
  summer 
  and 
  autumn. 
  The 
  

   top 
  of 
  the 
  mountain 
  southwest 
  of 
  Wawarsing 
  is 
  a 
  wide 
  plateau 
  

   which 
  is 
  traversed 
  by 
  the 
  valley 
  of 
  Stony 
  creek. 
  Its 
  surface 
  is 
  

   very 
  irregular 
  and 
  consists 
  of 
  low 
  cliffs 
  of 
  the 
  base 
  grit. 
  

  

  The 
  relation 
  of 
  the 
  Shawangunk 
  grit 
  to 
  the 
  Hudson 
  river 
  shales 
  

   in 
  the 
  Shawangunk 
  mountain 
  region 
  is 
  one 
  of 
  slight 
  but 
  persist- 
  

   ent 
  unconformity. 
  The 
  coarse 
  grit 
  lies 
  directly 
  on 
  the 
  slate 
  and 
  

   there 
  is 
  an 
  intervening 
  eroded 
  surface. 
  This 
  erosion 
  has 
  

   truncated 
  low 
  arches 
  of 
  slate 
  bui 
  channeled 
  its 
  surface 
  only 
  

   slightly. 
  Exposures 
  of 
  the 
  relations 
  are 
  everywhere 
  abundant. 
  

   One 
  of 
  the 
  best 
  instances 
  is 
  along 
  the 
  road 
  from 
  Minnewaska 
  to 
  

   New 
  Paltz, 
  at 
  a 
  point 
  two 
  miles 
  south 
  of 
  Lake 
  Mohonk. 
  Here 
  

   along 
  the 
  mountain 
  slope 
  a 
  very 
  low 
  arch 
  of 
  the 
  grit 
  is 
  exposed 
  

   with 
  underlying 
  shales 
  in 
  an 
  arch 
  that 
  is 
  plainly 
  seen 
  to 
  be 
  

   materially 
  steeper. 
  There 
  is 
  divergence 
  of 
  dip 
  in 
  nearly 
  every 
  

   locality, 
  varying 
  from 
  very 
  slight 
  to 
  ten 
  degrees, 
  but 
  several 
  

   points 
  were 
  seen 
  where 
  it 
  w 
  r 
  as 
  hardly 
  perceptible. 
  

  

  The 
  origin 
  and 
  history 
  of 
  the 
  lakes 
  is 
  not 
  entirely 
  clear, 
  but 
  

   they 
  appear 
  to 
  be 
  due 
  to 
  glacial 
  agencies. 
  The 
  principal 
  feature 
  

   has 
  been 
  a 
  local 
  deepening 
  and 
  widening 
  of 
  a 
  pre-existing 
  valley, 
  

   aided, 
  in 
  the 
  case 
  of 
  Lake 
  Mohonk 
  at 
  least, 
  by 
  the 
  presence 
  of 
  

   s 
  hales 
  at 
  the 
  point 
  now 
  occupied 
  by 
  the 
  lake. 
  They 
  do 
  not 
  

   appear 
  to 
  be 
  due 
  in 
  great 
  measure 
  to 
  damming 
  by 
  glacial 
  or 
  other 
  

   debris, 
  or 
  to 
  dislocation. 
  

  

  Owing 
  to 
  its 
  prominence 
  the 
  mountain 
  has 
  been 
  long 
  exposed 
  

   to 
  erosion. 
  Originally 
  the 
  grit 
  was 
  overlaid 
  by 
  a 
  great 
  mass 
  of 
  

   limestones 
  and 
  shales 
  and 
  the 
  rocks 
  of 
  the 
  Catskill 
  mountain, 
  

   but 
  these 
  were 
  removed 
  far 
  down 
  into 
  the 
  Rondout 
  valley 
  at 
  an 
  

   early 
  period. 
  During 
  the 
  glacial 
  epoch 
  there 
  was 
  extensive 
  

   erosion 
  and 
  the 
  removal 
  of 
  great 
  masses 
  of 
  the 
  grit, 
  some 
  of 
  which 
  

   are 
  now 
  found 
  in 
  the 
  glacial 
  drift 
  far 
  to 
  the 
  southward. 
  The 
  sur- 
  

   face 
  of 
  the 
  rocks 
  was 
  scratched, 
  scored 
  and 
  polished 
  by 
  the 
  pebbles 
  

  

  