﻿42 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  proves 
  that 
  the 
  Potsdam 
  sea 
  occupied 
  all 
  these 
  regions. 
  Along 
  the 
  

   southwestern 
  border 
  of 
  the 
  Adirondacks 
  the 
  Potsdam 
  is 
  absent 
  and 
  

   there 
  is 
  not 
  the 
  slightest 
  evidence 
  that 
  it 
  ever 
  was 
  present, 
  so 
  that 
  

   region 
  must 
  have 
  been 
  dry 
  land 
  in 
  Potsdam 
  time. 
  In 
  the 
  south- 
  

   eastern 
  Adirondacks 
  the 
  Potsdam 
  sea 
  certainly 
  extended 
  in 
  as 
  far 
  

   as 
  Wells 
  (southern 
  Hamilton 
  county) 
  and 
  North 
  River 
  (north- 
  

   western 
  Warren 
  county), 
  because 
  small 
  outlying 
  masses 
  of 
  Pots- 
  

   dam 
  sandstone 
  occur 
  at 
  those 
  places. 
  These 
  outlying 
  masses 
  were 
  

   formerly 
  connected 
  with 
  the 
  larger 
  areas 
  but 
  have 
  become 
  com- 
  

   pletely 
  separated 
  from 
  them 
  by 
  extensive 
  (Postpaleozoic) 
  erosion 
  

   and 
  downfaulting. 
  There 
  is 
  no 
  evidence 
  whatever 
  that 
  the 
  sea 
  

   covered 
  the 
  heart 
  of 
  the 
  Adirondacks. 
  To 
  summarize 
  for 
  northern 
  

   New 
  York, 
  we 
  may 
  say 
  that 
  the 
  Potsdam 
  (Upper 
  Cambric) 
  sea 
  

   covered 
  the 
  whole 
  region 
  except 
  the 
  central 
  and 
  southwestern 
  

   Adirondacks 
  which 
  stood 
  out 
  as 
  a 
  great 
  island 
  in 
  the 
  midst 
  of 
  that 
  

   ocean. 
  Southeastern 
  New 
  York 
  certainly, 
  and 
  the 
  middle 
  eastern 
  

   border 
  of 
  the 
  State 
  probably, 
  were 
  covered 
  by 
  the 
  Upper 
  Cambric 
  

   sea, 
  but 
  whether 
  that 
  sea 
  extended 
  over 
  the 
  rest 
  of 
  the 
  State 
  has 
  

   not 
  been 
  determined 
  because 
  all 
  early 
  Paleozoic 
  strata, 
  if 
  present, 
  

   are 
  now 
  deeply 
  buried. 
  

  

  What 
  do 
  we 
  know 
  about 
  the 
  character 
  of- 
  the 
  topography 
  of 
  the 
  

   land 
  over 
  which 
  that 
  ancient 
  Potsdam 
  sea 
  spread? 
  As 
  a 
  result 
  of 
  

   the 
  very 
  long 
  erosion 
  during 
  late 
  Precambric 
  and 
  early 
  Paleozoic, 
  

   thousands 
  of 
  feet 
  of 
  material 
  had 
  been 
  removed 
  so 
  that 
  rocks 
  which 
  

   had 
  been 
  so 
  deeply 
  buried 
  were 
  exposed 
  at 
  the 
  surface, 
  and 
  the 
  

   whole 
  country 
  must 
  have 
  been 
  well 
  worn 
  down. 
  Was 
  the 
  region 
  

   worn 
  down 
  to 
  the 
  condition 
  of 
  a 
  peneplain 
  ? 
  Recent 
  detailed 
  studies 
  

   on 
  all 
  sides 
  of 
  the 
  Adirondacks 
  furnish 
  a 
  very 
  satisfactory 
  answer 
  

   to 
  this 
  question. 
  In 
  many 
  places 
  the 
  Potsdam 
  has 
  been 
  seen 
  in 
  

   actual 
  contact 
  with 
  the 
  Precambric 
  rock 
  whose 
  surface 
  oftentimes 
  

   clearly 
  proves 
  that 
  the 
  whole 
  region 
  had 
  reached 
  a 
  peneplain 
  con- 
  

   dition. 
  Along 
  the 
  northeastern 
  Adirondacks 
  this 
  peneplain 
  was 
  

   considerably 
  rougher 
  than 
  along 
  the 
  northwestern 
  and 
  southwestern 
  

   portions. 
  This 
  is 
  explained 
  by 
  the 
  fact 
  that 
  the 
  northeastern 
  area 
  

   subsided 
  first 
  and 
  consequently 
  was 
  not 
  subject 
  to 
  wear 
  quite 
  so 
  

   long 
  as 
  the 
  latter 
  named 
  areas. 
  

  

  The 
  accompanying 
  figure 
  (no. 
  15) 
  affords 
  an 
  interesting 
  example 
  

   of 
  the 
  kind 
  of 
  peneplain 
  topography 
  here 
  considered. 
  It 
  demon- 
  

   strates 
  that 
  occasional 
  low 
  knobs 
  of 
  more 
  resistant 
  rock 
  (for 
  ex- 
  

   ample, 
  Grenville 
  quartzite) 
  protruded 
  above 
  the 
  otherwise 
  nearly 
  

   featureless 
  plain, 
  because 
  when 
  the 
  Potsdam 
  sea 
  overspread 
  the 
  

  

  