﻿GEOLOGY 
  OF 
  THOUSAND 
  ISLANDS 
  REGION 
  85 
  

  

  and 
  are 
  a 
  unity 
  with 
  them 
  also 
  in 
  that, 
  as 
  a 
  rule, 
  they 
  together 
  form 
  

   a 
  distinct 
  escarpment 
  above 
  the 
  Lowville 
  plateau. 
  In 
  some 
  cases, 
  

   however, 
  the 
  lowest 
  2 
  or 
  3 
  feet 
  of 
  the 
  chert 
  beds 
  have 
  remained 
  

   clinging 
  in 
  ver}' 
  irregular 
  patches 
  to 
  the 
  underlying 
  Lowville, 
  thus 
  

   forming 
  the 
  serpentine 
  shaped 
  outliers 
  seen 
  in 
  the 
  southern 
  portion 
  

   of 
  the 
  map. 
  

  

  The 
  authors, 
  under 
  the 
  necessity 
  of 
  drawing 
  a 
  definite 
  boundary 
  

   line 
  between 
  the 
  " 
  Black 
  River 
  " 
  and 
  Lowville 
  limestones, 
  which 
  

   would 
  meet 
  the 
  requirements 
  of 
  being 
  lithologically 
  and 
  faunistic- 
  

   ally 
  so 
  well 
  marked 
  that 
  it 
  could 
  be 
  mapped 
  with 
  sufficient 
  ease 
  and 
  

   precision, 
  decided 
  on 
  uniting 
  the 
  cherty 
  beds 
  with 
  the 
  Seven 
  foot 
  

   tier, 
  the 
  two 
  forming 
  a 
  physiographic 
  and 
  economical 
  unit, 
  as 
  demon- 
  

   strated 
  by 
  their 
  being 
  quarried 
  together 
  at 
  Chaumont 
  and 
  other 
  

   places. 
  Dr 
  Llrich's 
  investigations 
  had 
  shown 
  him 
  a 
  more 
  com- 
  

   plete 
  section 
  in 
  Kentucky 
  from 
  which 
  it 
  became 
  apparent 
  that 
  the 
  

   cherty 
  beds 
  are 
  intimately 
  connected 
  there 
  with 
  the 
  rest 
  of 
  the 
  

   Lowville 
  and 
  that 
  the 
  unconformity 
  observed 
  in 
  the 
  Waterto^vn 
  

   region 
  between 
  the 
  cherty 
  beds 
  and 
  the 
  other 
  Lowville 
  represents 
  

   the 
  hiatus 
  which 
  is 
  filled 
  in 
  Kentucky 
  and 
  elsewhere 
  by 
  beds 
  of 
  

   transitional 
  character, 
  while 
  on 
  the 
  other 
  hand 
  the 
  cherty 
  beds 
  

   were 
  found 
  to 
  be 
  also 
  separated 
  by 
  an 
  unconformity 
  from 
  the 
  over- 
  

   lying 
  beds. 
  Since, 
  moreover, 
  the 
  " 
  Seven 
  foot 
  tier 
  " 
  or 
  Hall's 
  

   " 
  Black 
  River 
  limestone 
  " 
  is 
  of 
  but 
  local 
  importance, 
  while 
  the 
  Low- 
  

   ville, 
  including 
  the 
  cherty 
  beds, 
  is 
  a 
  most 
  persistent 
  unit 
  over 
  a 
  very 
  

   large 
  area, 
  it 
  has 
  been 
  finally 
  deemed 
  preferable 
  by 
  the 
  authors 
  to 
  

   disregard 
  the 
  local 
  conditions 
  of 
  the 
  Waterto\vn 
  region, 
  and 
  to 
  re- 
  

   tain 
  the 
  '' 
  cherty 
  beds 
  " 
  limestone 
  as 
  a 
  sublivision 
  of 
  the 
  Lowville 
  

   limestone, 
  under 
  the 
  term 
  "' 
  Leray^ 
  limestone," 
  on 
  account 
  of 
  the 
  

   typical 
  exposures 
  in 
  the 
  town 
  of 
  Leray. 
  

  

  The 
  following 
  diagram 
  indicates 
  the 
  relations 
  of 
  the 
  beds 
  as 
  now 
  

   understood 
  by 
  us 
  : 
  

  

  ' 
  Watertown 
  limestone 
  

   Black 
  River 
  r 
  Leray 
  limestone 
  member 
  

  

  group 
  " 
  Lowville 
  formation 
  J 
  

  

  1^ 
  Lowville 
  limestone 
  s. 
  str. 
  

  

  Since 
  a 
  very 
  irregular 
  surface 
  is 
  observable 
  beween 
  the 
  upper- 
  

   most 
  tier 
  of 
  cherty 
  beds, 
  about 
  6 
  feet 
  thick, 
  and 
  the 
  underlying 
  beds 
  

   \see 
  section 
  of 
  Klock's 
  quarry, 
  posfca 
  p. 
  90], 
  and 
  this 
  bed 
  contains 
  

   the 
  cephalopods 
  more 
  frequently 
  than 
  the 
  other 
  cherty 
  beds, 
  Dr 
  

  

  1 
  Owing 
  to 
  an 
  error 
  of 
  the 
  printer 
  this 
  word 
  was 
  made 
  to 
  read 
  Leroy 
  

   on 
  page 
  72 
  of 
  Museum 
  Bulletin 
  138. 
  

  

  