﻿GEOLOGY 
  OF 
  THOUSAND 
  ISLANDS 
  REGION 
  II 
  5 
  

  

  in 
  the 
  case 
  of 
  the 
  other 
  formations 
  the 
  great 
  majority 
  of 
  the 
  out- 
  

   Hers 
  are 
  owing 
  to 
  wear 
  on 
  rocks 
  of 
  this 
  folded 
  type. 
  The 
  numerous 
  

   outhers 
  of 
  Leray 
  Hmestone 
  on 
  the 
  Theresa 
  and 
  Clayton 
  sheets 
  

   chiefly 
  mark 
  the 
  positions 
  of 
  basins 
  (points 
  of 
  intersection 
  of 
  

   synclines 
  of 
  both 
  series 
  of 
  folds), 
  the 
  dips 
  being 
  everywhere 
  in 
  

   toward 
  the 
  center. 
  Similarly 
  the 
  Lowville 
  inliers 
  which 
  Ruedemann 
  

   has 
  mapped 
  on 
  the 
  Clayton 
  sheet, 
  north 
  of 
  Threemile 
  and 
  Guffin 
  

   bays, 
  mark 
  the 
  summit 
  of 
  domes 
  (intersections 
  of 
  anticlines) 
  with 
  

   dip 
  outwardly 
  from 
  the 
  center. 
  In 
  the 
  case 
  of 
  some 
  of 
  the 
  outliers 
  

   however, 
  those 
  of 
  the 
  Theresa 
  formation 
  on 
  the 
  Potsdam 
  west 
  of 
  

   Theresa 
  for 
  example, 
  the 
  dome 
  structure 
  instead 
  of 
  the 
  basin 
  struc- 
  

   ture 
  is 
  exhibited, 
  the 
  outlier 
  showing 
  no 
  prominent 
  inface, 
  and 
  with 
  

   dip 
  outward 
  from 
  the 
  center. 
  The 
  domed 
  structure 
  often 
  shows 
  

   excellently 
  elsewhere, 
  as 
  for 
  example 
  in 
  the 
  Theresa 
  formation 
  at 
  

   Orleans 
  Four 
  Corners 
  (Theresa 
  sheet) 
  where 
  the 
  upper 
  surface 
  of 
  

   a 
  single 
  massive 
  layer 
  of 
  the 
  formation 
  protudes 
  above 
  the 
  soil 
  as 
  a 
  

   low, 
  shallow 
  dome, 
  dipping 
  outwardly 
  in 
  all 
  directions. 
  Many 
  other 
  

   examples 
  might 
  be 
  cited 
  and, 
  owing 
  to 
  the 
  abundance 
  of 
  rock 
  ex- 
  

   posures 
  in 
  the 
  district 
  the 
  evidence 
  of 
  these 
  structures 
  is 
  unusually 
  

   clear, 
  and 
  it 
  is 
  quite 
  certain 
  that 
  these 
  two 
  sets 
  of 
  low, 
  cross 
  folds 
  

   occur. 
  

  

  Postglacial 
  folds. 
  There 
  are 
  in 
  the 
  district 
  at 
  least 
  a 
  half 
  

   dozen 
  examples 
  of 
  low 
  folds, 
  or 
  buckles, 
  of 
  the 
  surface 
  rocks, 
  wdiich 
  

   are 
  of 
  very 
  recent 
  origin. 
  Though 
  they 
  form 
  only 
  a 
  minor 
  struc- 
  

   tural 
  and 
  topographic 
  feature, 
  they 
  are 
  rather 
  unusual 
  and 
  the 
  in- 
  

   terest 
  attaching 
  to 
  them 
  is 
  out 
  of 
  all 
  proportion 
  to 
  their 
  size 
  and 
  

   frequency. 
  The 
  writer 
  has 
  noted 
  three 
  of 
  them 
  in 
  the 
  limestones, 
  

   Lowville 
  and 
  Pamelia, 
  and 
  Professor 
  Fairchild 
  has 
  called 
  his 
  atten- 
  

   tion 
  to 
  two 
  others. 
  In 
  addition 
  at 
  least 
  one 
  occurs 
  in 
  the 
  Potsdam 
  

   sandstone. 
  The 
  limestone 
  folds 
  seem 
  all 
  to 
  conform 
  to 
  a 
  common 
  

   type 
  so 
  that 
  a 
  description 
  of 
  one 
  of 
  them, 
  and 
  of 
  the 
  one 
  in 
  the 
  

   Potsdam, 
  will 
  answer 
  every 
  purpose. 
  

  

  The 
  Potsdam 
  fold 
  occurs 
  2 
  miles 
  south 
  of 
  Chippewa 
  Bay, 
  in 
  the 
  

   northeastern 
  portion 
  of 
  the 
  Alexandria 
  sheet, 
  is 
  near 
  the 
  roadside 
  

   and 
  easily 
  visible 
  from 
  it. 
  It 
  is 
  40 
  yards 
  long, 
  trends 
  n. 
  28° 
  w., 
  and 
  

   a 
  view 
  of 
  it, 
  taken 
  at 
  the 
  south 
  end, 
  appears 
  in 
  plate 
  29. 
  It 
  rises 
  

   sharply 
  from 
  the 
  surface 
  of 
  an 
  extensive 
  plain, 
  underlaid 
  by 
  nearly 
  

   horizontal 
  sandstone, 
  with 
  but 
  a 
  scanty 
  soil 
  covering 
  and 
  much 
  bare 
  

   rock 
  exposed. 
  The 
  fold 
  is 
  of 
  bared 
  rock 
  with 
  beautifully 
  glaciated 
  

   surface, 
  whose 
  striatioiis 
  demonstrate 
  that 
  the 
  buckling 
  has 
  Occurred 
  

   since 
  the 
  glaciation. 
  The 
  central 
  portion 
  is 
  buckled 
  up 
  about 
  12 
  feet. 
  

   The 
  photograph 
  clearly 
  shows 
  that, 
  owing 
  to 
  compression, 
  the 
  rocks 
  

  

  