﻿396 
  Forty-seventh 
  Report 
  on 
  the 
  State 
  Museum. 
  

  

  which 
  lie 
  about 
  200 
  feet 
  below 
  and 
  extend 
  eastward 
  to 
  

   the 
  river. 
  This 
  esearpment 
  extends 
  for 
  many 
  miles 
  southward 
  at 
  

   the 
  eastern 
  edge 
  of 
  the 
  Helderberg 
  formation, 
  although 
  it 
  is 
  

   sometimes 
  buried 
  hj 
  overlapping 
  drift 
  hills 
  and 
  it 
  is 
  frequently 
  

   broken 
  through 
  by 
  streams. 
  

  

  In 
  \he 
  southern 
  part 
  of 
  Albany 
  county 
  the 
  rolling 
  area 
  above 
  

   referred 
  to 
  gives 
  place 
  to 
  the 
  ridges 
  of 
  Appalachian 
  type, 
  which 
  

   extend 
  southward 
  through 
  Greene 
  and 
  Ulster 
  counties 
  in 
  a 
  

   narrow 
  belt 
  between 
  the 
  high 
  hilis 
  of 
  Hamilton. 
  The 
  physiog- 
  

   raphy 
  of 
  this 
  belt 
  is 
  fully 
  illustrated 
  in 
  plates 
  3, 
  4 
  and 
  6, 
  except- 
  

   ing 
  for 
  short 
  distances 
  about 
  Catslrill 
  and 
  Rondout, 
  where 
  the 
  

   same 
  features 
  prevail. 
  

  

  South 
  of 
  Rosendale 
  the 
  ridges 
  merge 
  into 
  the 
  slopes 
  of 
  the 
  

   Shawangunk 
  mountain, 
  which 
  rises 
  rapidly 
  and 
  attains 
  great 
  

   prominence. 
  Its 
  characteristics 
  are 
  the 
  wide 
  corrugated 
  western 
  

   slope, 
  its 
  great, 
  precipices 
  facing 
  eastward, 
  its 
  partially 
  inclosed 
  

   high 
  hill 
  areas 
  of 
  slate 
  notably 
  southeast 
  of 
  Ellenville 
  and 
  north- 
  

   west 
  of 
  New 
  Paltz, 
  and 
  its 
  elevated 
  cliff-encircled 
  lakes, 
  of 
  which 
  

   Mohonk 
  and 
  Minnewaska 
  are 
  the 
  best 
  known. 
  

  

  Stratigraphy. 
  

  

  General 
  Relations. 
  — 
  In 
  the 
  reports 
  of 
  Hall, 
  Yanuxem 
  and 
  

   Mather, 
  the 
  agriculture 
  by 
  Emmons, 
  and 
  papers 
  by 
  W. 
  M. 
  Davis 
  

   and 
  others, 
  there 
  are 
  more 
  or 
  less 
  extended 
  descriptions 
  of 
  the 
  

   several 
  formations 
  to 
  which 
  this 
  report 
  relates, 
  and 
  in 
  greater 
  

   part 
  their 
  general 
  relations 
  have 
  been 
  well 
  known 
  for 
  over 
  half 
  

   a 
  century. 
  In 
  the 
  course 
  of 
  my 
  examination 
  of 
  the 
  region, 
  how- 
  

   ever, 
  many 
  local 
  details 
  of 
  character, 
  distribution, 
  overlap 
  and 
  

   thickness 
  not 
  heretofore 
  described 
  have 
  been 
  noted, 
  and 
  these 
  

   are 
  presented 
  in 
  this 
  chapter 
  as 
  part 
  of 
  a 
  systematized 
  resume 
  of 
  

   the 
  stratigraphy. 
  

  

  In 
  plate 
  1 
  I 
  have 
  given 
  a 
  series 
  of 
  columnar 
  sections 
  illustrat- 
  

   ing 
  the 
  general 
  stratigraphic 
  variations 
  of 
  the 
  formations 
  between 
  

   the 
  Hamilton 
  and 
  Hudson 
  River 
  shales 
  throughout 
  New 
  York 
  

   and 
  to 
  northwestern 
  New 
  Jersey. 
  The 
  first 
  three* 
  are 
  based 
  

   mainly 
  on 
  well 
  boring 
  records 
  described 
  by 
  Prosser* 
  and 
  Ash 
  - 
  

  

  * 
  The 
  thickness 
  of 
  the 
  Devonian 
  and 
  Silurian 
  rocks 
  of 
  western 
  central 
  New 
  York. 
  Am. 
  

   Geologist, 
  vol 
  6, 
  pp. 
  199-211. 
  1890. 
  The 
  thickness 
  of 
  the 
  Devonian 
  and 
  Silurian 
  rocks 
  of 
  central 
  

   New 
  York. 
  Geol. 
  Soc. 
  America, 
  Bull., 
  vol. 
  4, 
  pp. 
  91-119, 
  1898. 
  The 
  thickness 
  of 
  the 
  Devonian 
  

   and 
  Silurian 
  rocks 
  of 
  western 
  New 
  York 
  approximately 
  along 
  the 
  Genesee 
  river. 
  Rochester 
  

   Acad. 
  Sci., 
  Proa, 
  vol. 
  2, 
  pp. 
  49-104, 
  plates. 
  1892. 
  

  

  