﻿GEOLOGY 
  OF 
  THOUSAND 
  ISLANDS 
  REGION 
  8 
  1 
  

  

  the 
  southern 
  branch 
  of 
  Horse 
  creek 
  on 
  the 
  Clayton 
  quadrangle 
  

   and 
  best 
  along 
  the 
  Black 
  river 
  just 
  east 
  of 
  the 
  boundary 
  of 
  the 
  

   map. 
  Such 
  beds 
  are 
  seen 
  in 
  the 
  lower 
  third 
  of 
  the 
  exposure 
  on 
  

   plate 
  19; 
  other 
  bunchy 
  surfaced 
  layers 
  also 
  appear, 
  with 
  the 
  

   depressions 
  filled 
  in 
  with 
  shaly 
  material, 
  which 
  seem 
  clearly 
  due 
  

   to 
  rill 
  action 
  on 
  tide 
  flats. 
  

  

  While 
  the 
  sand 
  grains 
  which 
  are 
  found 
  in 
  greater 
  or 
  smaller 
  

   number 
  floating 
  in 
  the 
  basal 
  limestones 
  indicate, 
  if 
  we 
  may 
  

   follow 
  recent 
  investigations, 
  the 
  conditions 
  of 
  quiet 
  embayments, 
  

   in 
  which 
  sands 
  washed 
  in 
  from 
  the 
  land, 
  drifted 
  out 
  into 
  the 
  bay 
  

   and 
  gradually 
  sank 
  to 
  the 
  bottom, 
  becoming 
  imbedded 
  in 
  the 
  

   limestone 
  mud, 
  the 
  following 
  beds 
  indicate 
  that 
  this 
  sea 
  became 
  

   gradually 
  deepened. 
  The 
  lower 
  division 
  still 
  exhibits 
  in 
  the 
  

   shaly 
  beds 
  the 
  sun 
  cracks 
  and 
  ripple-marks 
  and 
  numerous 
  mud 
  

   balls 
  characteristic 
  of 
  mud 
  flats 
  while 
  the 
  upper 
  beds 
  in 
  their 
  

   more 
  uniform, 
  massive 
  character 
  contain 
  the 
  criteria 
  of 
  deposi- 
  

   tion 
  farther 
  off 
  the 
  coast 
  line. 
  It 
  follows 
  thence 
  that 
  the 
  Low- 
  

   ville 
  sea 
  was 
  an 
  advancing 
  sea 
  in 
  the 
  area 
  here 
  mapped. 
  From 
  

   the 
  development 
  of 
  the 
  Lowville 
  in 
  the 
  ]^Iohawk 
  valley 
  and 
  north 
  

   of 
  the 
  Adirondacks, 
  it 
  can 
  be 
  inferred 
  that 
  this 
  transgression 
  took 
  

   place 
  from 
  the 
  southwest. 
  In 
  the 
  ]\Iohawk 
  valley 
  the 
  distribution 
  

   of 
  the 
  Lowville 
  is 
  very 
  erratic, 
  as 
  fully 
  discussed 
  by 
  Gushing 
  in 
  a 
  

   former 
  paper 
  [Geolog}^ 
  of 
  the 
  Northern 
  Adirondack 
  Region], 
  it 
  

   being 
  entirely 
  absent 
  in 
  some 
  localities 
  while 
  in 
  others 
  it 
  is 
  con- 
  

   nected 
  by 
  so 
  called 
  passage 
  beds 
  with 
  the 
  underlying 
  Beekmantown. 
  

   This 
  erratic 
  distribution 
  is 
  then 
  clearly 
  due 
  to 
  the 
  irregularity 
  of 
  

   the 
  surface 
  over 
  which 
  the 
  sea 
  advanced, 
  the 
  Mohawk 
  valley 
  inter- 
  

   secting 
  the 
  deeply 
  indented 
  coast 
  line 
  of 
  the 
  Adirondack 
  peninsula 
  

   in 
  Lowville 
  time. 
  In 
  the 
  Champlain 
  basin 
  at 
  the 
  base 
  of 
  the 
  Black 
  

   River 
  group 
  an 
  outcrop 
  of 
  typical 
  Lowville 
  rock 
  occurs 
  in 
  the 
  Crown 
  

   Point 
  section. 
  The 
  bed 
  referred 
  to 
  consists 
  of 
  5 
  feet 
  of 
  dove 
  lime- 
  

   stone 
  with 
  Ph}i:opsis 
  tubes 
  but 
  otherwise 
  apparently 
  unfossiliferous. 
  

   However, 
  12 
  feet 
  above 
  this 
  dove 
  limestone 
  the 
  writer 
  found 
  

   a 
  large 
  colony 
  of 
  Tetradium 
  cellulosum 
  together 
  with 
  

   Orthoceras 
  recticameratum, 
  another 
  typical 
  Low- 
  

   ville 
  fossil, 
  thereby 
  clearly 
  demonstrating 
  the 
  presence 
  of 
  the 
  Low- 
  

   ville 
  fauna 
  in 
  the 
  Champlain 
  basin. 
  

  

  Four 
  species 
  of 
  fossils 
  have 
  to 
  be 
  considered 
  as 
  highly 
  charac- 
  

   teristic 
  of 
  the 
  Lowville 
  formation 
  in 
  the 
  area 
  here 
  mapped, 
  viz 
  : 
  

  

  Tetradium 
  cellulosum 
  (Hall) 
  

  

  Orthoceras 
  multicameratum 
  (Emmons) 
  Hall 
  

  

  O. 
  recticameratum 
  Hall 
  

  

  Bathyurus 
  extans 
  (Hall) 
  

  

  