﻿Report 
  of 
  the 
  State 
  Geologist. 
  489 
  

  

  The 
  Wallkill 
  valley 
  region 
  comprises 
  broad 
  belts 
  of 
  level 
  or 
  

   gently-rolling' 
  lands 
  along 
  the 
  Wallkill, 
  Swartzkill 
  and 
  Platte- 
  

   kill 
  and 
  rounded 
  hills 
  of 
  moderate 
  elevation 
  on 
  the 
  adjacent 
  

   slopes. 
  Along 
  the 
  base 
  of 
  the 
  Shawangunk 
  mountain 
  these 
  hills 
  

   increase 
  considerably 
  in 
  altitude, 
  but 
  their 
  rounded 
  form 
  is 
  

   unchanged. 
  

  

  East 
  of 
  the 
  Wallkill 
  valley 
  there 
  rises 
  the 
  series 
  of 
  high 
  ridges 
  

   which 
  constitute 
  Marlborough 
  mountain 
  and 
  its 
  northern 
  con- 
  

   tinuation 
  to 
  Hussy 
  hill 
  south 
  of 
  Kondout. 
  They 
  present 
  con- 
  

   siderable 
  diversity 
  in 
  topography, 
  but 
  are 
  mainly 
  rocky 
  and 
  very 
  

   steep 
  sided. 
  The 
  higher 
  ridges 
  average 
  about 
  1000 
  feet 
  in 
  

   altitude, 
  but 
  there 
  are 
  many 
  irregularities 
  in 
  their 
  course 
  as 
  

   shown 
  in 
  the 
  stereogram. 
  The 
  deepest 
  depressions 
  across 
  the 
  

   range 
  are 
  west 
  of 
  Highland 
  and 
  Ulster 
  Park 
  stations. 
  

  

  General 
  Structure. 
  

  

  The 
  general 
  structural 
  relations 
  of 
  Ulster 
  county 
  are 
  repre- 
  

   sented 
  in 
  sections 
  of 
  figure 
  1. 
  

  

  The 
  rocks 
  are 
  a 
  series 
  of 
  widely 
  extended 
  sheets 
  of 
  sandstone, 
  

   shales, 
  limestone 
  and 
  conglomerates. 
  The 
  uppermost 
  or 
  youngest 
  

   member 
  is 
  on 
  the 
  higher 
  summits 
  of 
  the 
  Catskill 
  mountains, 
  and 
  

   the 
  lowest 
  or 
  oldest 
  which 
  appears 
  on 
  the 
  surface, 
  is 
  a 
  limestone 
  

   which 
  occupies 
  a 
  very 
  small 
  area 
  in 
  the 
  southeastern 
  corner 
  of 
  

   the 
  county. 
  

  

  In 
  the 
  Catskill 
  mountains 
  and 
  their 
  foothills 
  there 
  are 
  several 
  

   thousand 
  feet 
  of 
  sandstones 
  and 
  shales 
  which 
  are 
  overlaid 
  in 
  the 
  

   higher 
  regions 
  by 
  conglomeratic 
  sandstones. 
  These 
  beds 
  all 
  dip 
  

   gently 
  to 
  the 
  west-southwest, 
  possibly 
  with 
  slight 
  undulations. 
  

   In 
  the 
  lower 
  lands 
  and 
  ridges 
  east 
  of 
  the 
  Catskill 
  mountains 
  

   there 
  is 
  a 
  succession 
  of 
  limestones 
  and 
  shales 
  which 
  to 
  the 
  south- 
  

   ward 
  are 
  underlaid 
  by 
  a 
  sheet 
  of 
  hard 
  conglomerate 
  which 
  gives 
  

   rise 
  to 
  Shawangunk 
  mountain. 
  In 
  this 
  belt 
  the 
  gentle 
  westerly 
  

   dip 
  gradually 
  gives 
  place 
  to 
  flexures, 
  some 
  of 
  which 
  are 
  of 
  con- 
  

   siderable 
  steepness. 
  The 
  limestone 
  series 
  and 
  Shawangunk 
  con- 
  

   glomerate 
  are 
  underlaid 
  unconformably 
  by 
  the 
  shales 
  and 
  sand- 
  

   stones 
  of 
  the 
  Hudson 
  river 
  formations 
  which 
  extend 
  to 
  the 
  

   Hudson 
  river. 
  In 
  the 
  southeastern 
  portion 
  of 
  the 
  county 
  the 
  

   beds 
  are 
  steeply 
  overturned 
  and 
  inclined 
  mainly 
  to 
  the 
  eastward. 
  

   62 
  

  

  