﻿GEOLOGY 
  OF 
  THE 
  PORT 
  LEYDEN 
  QUADRANGLE 
  2'J 
  

  

  A 
  section 
  measured 
  by 
  the 
  writer 
  i^ 
  miles 
  north-northwest 
  of 
  

   Lyons 
  Falls, 
  and 
  along 
  Mill 
  creek, 
  shows 
  about 
  54 
  feet 
  of 
  Lowville. 
  

   This 
  section 
  is 
  continuous 
  with 
  that 
  of 
  the 
  Pamelia 
  already 
  referred 
  

   to. 
  Near 
  Denley 
  the 
  section 
  contains 
  about 
  57 
  feet 
  of 
  the 
  Lowville. 
  

  

  A 
  comparison 
  of 
  the 
  sections 
  at 
  these 
  widely 
  separated 
  localities 
  

   brings 
  out 
  some 
  interesting 
  facts, 
  the 
  chief 
  one 
  probably 
  being 
  that 
  

   the 
  formation 
  shows 
  almost 
  exactly 
  the 
  same 
  thickness 
  throughout 
  

   the 
  whole 
  distance. 
  This 
  is 
  especially 
  significant 
  in 
  view 
  of 
  the 
  

   rapid 
  thinning 
  of 
  the 
  underlying 
  Pamelia. 
  Another 
  fact 
  is 
  the 
  

   great 
  similarity 
  of 
  the 
  beds 
  in 
  the 
  different 
  sections. 
  Thus 
  the 
  basal 
  

   conglomerate 
  always 
  lies 
  from 
  54 
  to 
  57 
  feet 
  below 
  the 
  summit, 
  

   while 
  another 
  conglomerate 
  apparently 
  always 
  lies 
  about 
  26 
  or 
  28 
  

   feet 
  below 
  the 
  summit 
  and 
  is 
  associated 
  with 
  a 
  heavy 
  bed 
  of 
  pure 
  

   dove 
  limestone 
  full 
  of 
  gastropods. 
  

  

  Near 
  the 
  west 
  edge 
  of 
  the 
  Remsen 
  quadrangle, 
  along 
  Black 
  river, 
  

   there 
  is 
  no 
  complete 
  section, 
  but 
  the 
  Lowville 
  is 
  probably 
  not 
  over 
  

   40 
  feet 
  thick. 
  On 
  the 
  Little 
  Falls 
  sheet 
  the 
  Lowville 
  varies 
  in 
  

   thickness 
  from 
  5 
  to 
  21 
  feet, 
  while 
  at 
  Canajoharie 
  it 
  is 
  absent 
  

   altogether. 
  Thus 
  the 
  outcropping 
  Lowville 
  along 
  the 
  southwestern 
  

   Adirondacks 
  shows 
  a 
  steady 
  increase 
  in 
  thickness 
  in 
  passing 
  from 
  

   Canajoharie 
  to 
  Port 
  Leyden. 
  

  

  Black 
  River 
  limestone 
  

  

  The 
  Black 
  River 
  limestone 
  is 
  so 
  named 
  because 
  of 
  its 
  typical 
  

   occurrence 
  along 
  Black 
  river. 
  It 
  is 
  a 
  hard, 
  fine 
  grained, 
  dark- 
  

   colored 
  to 
  almost 
  black, 
  limestone 
  which 
  breaks 
  with 
  a 
  smooth 
  frac- 
  

   ture. 
  Interspersed 
  through 
  the 
  limestone, 
  in 
  a 
  very 
  irregular 
  man- 
  

   ner, 
  are 
  small 
  patches 
  of 
  black 
  shale 
  which 
  causes 
  the 
  rock, 
  on 
  

   weathering, 
  to 
  break 
  into 
  lumpy 
  masses. 
  The 
  appearance 
  of 
  the 
  

   rock 
  is 
  pretty 
  well 
  shown 
  in 
  plate 
  6. 
  After 
  long 
  exposure 
  to 
  the 
  

   weather 
  the 
  surface 
  color 
  changes 
  to 
  a 
  light 
  gray. 
  The 
  rock 
  i:. 
  

   generally 
  massive 
  although 
  two 
  or 
  three 
  layers 
  can 
  usually 
  be 
  fairly 
  

   well 
  made 
  out. 
  Another 
  distinctive 
  feature 
  of 
  the 
  rock, 
  particularly 
  

   the 
  upper 
  portion, 
  is 
  the 
  presence 
  in 
  it 
  of 
  many 
  irregular 
  shaped 
  

   black 
  chert 
  nodules. 
  Among 
  the 
  abundant 
  fossils 
  are 
  fine 
  large 
  

   specimens 
  of 
  orthoceratites 
  and 
  columnar 
  corals 
  especially 
  well 
  

   exhibited 
  on 
  the 
  upper 
  waterworn 
  surfaces. 
  Hall 
  ^ 
  says 
  of 
  the 
  

   formation 
  '' 
  from 
  being 
  characterized 
  by 
  a 
  large 
  number 
  of 
  peculiar 
  

   fossils, 
  though 
  mainly 
  belonging 
  to 
  a 
  single 
  family, 
  it 
  is 
  regarded 
  

   as 
  worthy 
  of 
  separate 
  notice. 
  The 
  principal 
  and 
  most 
  prominent 
  

  

  ^ 
  Palaeontology 
  of 
  N. 
  Y. 
  1847. 
  1 
  146. 
  

  

  