﻿94 
  ^'EW 
  YORK 
  STATE 
  MUSEUM 
  

  

  in 
  respect 
  to 
  these 
  conditions 
  seems 
  now 
  quite 
  well 
  substantiated. 
  

   Our 
  immediate 
  district 
  in 
  late 
  Cambric 
  (Ozarkic) 
  time 
  sloped 
  to 
  the 
  

   east 
  and 
  received 
  the 
  thin 
  deposit 
  of 
  Potsdam 
  and 
  Theresa 
  beds 
  laid 
  

   down 
  in 
  the 
  western 
  end 
  of 
  the 
  St 
  Lawrence 
  trough. 
  Uplift 
  fol- 
  

   lowed 
  throughout 
  Xew 
  York, 
  produc'ng 
  unconformit}^ 
  between 
  these 
  

   beds 
  and 
  those 
  of 
  the 
  Beekmantown 
  which 
  follow. 
  Beekmantown 
  

   subsidence 
  seems 
  to 
  have 
  commenced 
  simultaneously 
  on 
  the 
  east, 
  

   west 
  and 
  south 
  sides 
  of 
  the 
  Adirondacks, 
  with 
  a 
  tilting 
  of 
  the 
  

   surface 
  in 
  our 
  district 
  here, 
  so 
  that 
  its 
  slope 
  was 
  to 
  the 
  south- 
  

   west, 
  instead 
  of 
  to 
  the 
  east. 
  This 
  was 
  quickly 
  followed 
  by 
  tilt- 
  

   ing 
  of 
  the 
  whole 
  region 
  to 
  the 
  east, 
  stopping 
  Beekmantown 
  de- 
  

   posit 
  on 
  the 
  west 
  and 
  south 
  sides 
  of 
  the 
  Adirondacks 
  and 
  confining 
  

   it 
  to 
  the 
  eastern 
  trough. 
  From 
  this 
  trough 
  a 
  bay 
  seems 
  to 
  have 
  de- 
  

   veloped 
  westward 
  up 
  the 
  St 
  Lawrence 
  trough, 
  during 
  Beekmantown 
  

   time. 
  The 
  Beekmantow^n 
  ^vas 
  brought 
  to 
  a 
  close 
  by 
  another 
  uplift 
  

   of 
  the 
  entire 
  northern 
  New" 
  York 
  region. 
  In 
  the 
  Theresa 
  district 
  

   this 
  time 
  gap 
  -was 
  a 
  long 
  one 
  during 
  which 
  icxx) 
  feet 
  or 
  more 
  of 
  

   Beekmantown 
  rocks 
  were 
  deposited 
  in 
  the 
  Champlain 
  trough, 
  and 
  a 
  

   much 
  greater 
  thickness 
  in 
  other 
  regions. 
  

  

  Through 
  these 
  early 
  times 
  then 
  our 
  district 
  had 
  a 
  general 
  slope 
  of 
  

   its 
  surface 
  toward 
  the 
  east, 
  though 
  with 
  an 
  inter^^ening 
  time 
  of 
  short 
  

   duration 
  during 
  which 
  the 
  slope 
  was 
  to 
  the 
  southwest. 
  There 
  were 
  

   three 
  depressions, 
  alternating 
  with 
  three 
  elevations 
  of 
  the 
  surface, 
  

   though 
  apparently 
  the 
  deposits 
  of 
  the 
  third 
  depression 
  just 
  failed 
  to 
  

   reach 
  the 
  district. 
  

  

  In 
  the 
  Champlain 
  valley 
  the 
  Beekmantown 
  is 
  succeeded 
  by 
  the 
  

   Chazy 
  limestone 
  formation, 
  the 
  two 
  being 
  separated 
  by 
  a 
  slight 
  un- 
  

   conformity, 
  indicating 
  that 
  the 
  Beekmantown 
  was 
  followed, 
  as 
  it 
  had 
  

   been 
  preceded, 
  by 
  general 
  uplift 
  of 
  the 
  whole 
  area. 
  Depression 
  was 
  

   then 
  renewed 
  in 
  that 
  trough 
  for 
  the 
  third 
  time, 
  and 
  for 
  the 
  third 
  

   time 
  a 
  ba}^ 
  was 
  developed 
  westward 
  from 
  it. 
  This 
  Chazy 
  bay, 
  how- 
  

   ever, 
  seems 
  not 
  to 
  have 
  reached 
  as 
  far 
  westw^ard 
  as 
  the 
  preceding 
  

   BeekmantOAvn 
  bay. 
  and 
  certainly 
  fell 
  many 
  miles 
  short 
  of 
  reaching 
  

   our 
  district 
  here. 
  

  

  The 
  Champlain 
  Chazy 
  is 
  divided 
  into 
  lower, 
  middle 
  and 
  upper 
  sub- 
  

   divisions. 
  The 
  typical 
  Chazy 
  rocks 
  are 
  limited 
  to 
  the 
  Champlain 
  

   trough 
  and 
  its 
  prolongation 
  north 
  and 
  south. 
  This 
  trough 
  was 
  

   separated 
  from 
  a 
  much 
  larger 
  depressed 
  area 
  to 
  the 
  westward, 
  by 
  a 
  

   land 
  barrier, 
  which 
  prevented 
  the 
  passage 
  of 
  organisms 
  from 
  the 
  one 
  

   basin 
  to 
  the 
  other. 
  At 
  the 
  same 
  time 
  therefore 
  in 
  which 
  the 
  Chazy 
  

   rocks 
  were 
  being 
  deposited 
  in 
  the 
  Champlain 
  trough, 
  other 
  deposits, 
  

   characterized 
  by 
  a 
  different 
  fauna, 
  were 
  forming 
  to 
  the 
  west 
  of 
  them, 
  

  

  