﻿22 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  Geologic 
  map 
  

  

  A 
  few 
  words, 
  descriptive 
  of 
  the 
  accompanying 
  geologic 
  map 
  may 
  

   be 
  added. 
  

  

  The 
  topography 
  is 
  indicated 
  chiefly 
  by 
  contour 
  Hnes. 
  These 
  

   lines 
  are 
  20 
  feet 
  apart, 
  and 
  each 
  connects 
  the 
  points 
  which 
  have 
  the 
  

   same 
  elevation 
  above 
  sealevel. 
  Thus 
  wherever 
  the 
  300 
  foot 
  con- 
  

   tour 
  line 
  occurs, 
  every 
  point 
  along 
  that 
  line 
  is 
  supposed 
  to 
  be 
  300 
  

   feet 
  above 
  sealevel. 
  The 
  level 
  of 
  Lake 
  Ontario 
  is 
  247 
  feet 
  above 
  

   the 
  sea; 
  therefore 
  the 
  hight 
  of 
  any 
  point 
  above 
  Lake 
  Ontario 
  can 
  be 
  

   calculated 
  from 
  the 
  contours. 
  Where 
  the 
  contours 
  are 
  close 
  

   together, 
  the 
  slope 
  of 
  the 
  country 
  is 
  steep; 
  where 
  far 
  apart, 
  it 
  is 
  

   gentle. 
  

  

  The 
  various 
  color 
  patterns 
  indicate 
  what 
  geologic 
  formations 
  

   would 
  be 
  shown 
  on 
  the 
  surface 
  of 
  any 
  given 
  area, 
  if 
  the 
  drift 
  cover- 
  

   ing 
  were 
  removed. 
  The 
  beds 
  of 
  this 
  region 
  all 
  dip 
  gently 
  south- 
  

   ward; 
  and, 
  as 
  we 
  proceed 
  northward, 
  the 
  lower 
  beds 
  rise 
  from 
  

   beneath 
  the 
  covering 
  of 
  the 
  higher. 
  Where 
  steep 
  clififs 
  occur, 
  as 
  

   in 
  the 
  gorge 
  of 
  the 
  river 
  or 
  at 
  Lewiston 
  or 
  Queenston, 
  the 
  lower 
  

   beds 
  crop 
  out 
  beneath 
  the 
  upper 
  ones 
  for 
  only 
  a 
  very 
  short 
  space; 
  

   hence 
  they 
  appear 
  on 
  the 
  map 
  as 
  narrow 
  color 
  bands 
  only. 
  The 
  

   'Character 
  of 
  the 
  outcrops 
  in 
  the 
  buried 
  St 
  Davids 
  channel 
  is 
  only 
  

   approximately 
  delineated, 
  to 
  the 
  extent 
  indicated 
  by 
  well 
  borings. 
  

   It 
  is 
  probably 
  much 
  more 
  irregular 
  than 
  is 
  shown. 
  

  

  The 
  outlines 
  of 
  the 
  edges 
  of 
  the 
  various 
  beds 
  from 
  Lewiston 
  east- 
  

   ward 
  are 
  taken 
  from 
  a 
  map 
  by 
  G. 
  K. 
  Gilbert, 
  the 
  man 
  who 
  more 
  

   than 
  any 
  other 
  is 
  identified 
  with 
  geologic 
  studies 
  at 
  Niagara. 
  The 
  

   outcrops 
  of 
  the 
  Onondaga 
  and 
  waterlime 
  beds 
  are 
  taken 
  from 
  a 
  map 
  

   by 
  Prof. 
  L 
  P. 
  Bishop. 
  For 
  the 
  other 
  outlines 
  the 
  author 
  is 
  responsi- 
  

   ble. 
  

  

  A 
  few 
  statistics'^ 
  

  

  Hight 
  of 
  American 
  falls, 
  Oct. 
  4, 
  1842 
  167.7 
  feet 
  

  

  " 
  Horseshoe 
  falls, 
  " 
  • 
  ^158.5 
  

  

  Mean 
  total 
  recession 
  of 
  American 
  falls 
  between 
  1842 
  

  

  and 
  1890 
  30-75 
  " 
  

  

  Xhiefiy 
  from 
  the 
  annual 
  reports 
  of 
  the 
  commissioners 
  of 
  the 
  state 
  

   reservation. 
  

  

  ^The 
  hights 
  vary 
  from 
  4 
  to 
  20 
  feet 
  with 
  the 
  elevation 
  of 
  the 
  water 
  in 
  

   the 
  river 
  below 
  the 
  falls. 
  

  

  