﻿234 
  FORTF-SEVENTH 
  REPORT 
  ON 
  THE 
  STATE 
  MUSEUM. 
  

  

  venustula, 
  and 
  Phacops 
  rana 
  being 
  abundant, 
  but 
  fossils 
  are 
  rare 
  

   in 
  the 
  rest 
  of 
  the 
  rock, 
  which 
  is 
  very 
  dark 
  when 
  freshly 
  broken, 
  

   with 
  a 
  slightly 
  bluish 
  shade, 
  and 
  so 
  fine, 
  hard 
  and 
  glistening 
  as 
  

   to 
  resemble 
  flint. 
  When 
  long 
  exposed 
  it 
  becomes 
  light 
  drab 
  in 
  

   color. 
  The 
  usual 
  tendency 
  to 
  crumble 
  into 
  small 
  angular 
  

   blocks 
  from 
  weathering 
  does 
  not 
  appear 
  here, 
  the 
  fallen 
  masses 
  

   remaining 
  in 
  large 
  blocks 
  having 
  the 
  full, 
  thickness 
  of 
  the 
  

   stratum. 
  In 
  the 
  less 
  compact 
  shaly 
  part 
  at 
  the 
  bottom 
  of 
  the 
  

   lower 
  and 
  thicker 
  layer 
  there 
  occurs 
  considerable 
  iron 
  pyrites 
  

   in 
  the 
  form 
  of 
  nodules 
  and 
  shapes 
  resembling 
  the 
  peculiar 
  casts 
  of 
  

   small 
  twigs 
  that 
  are 
  so 
  abundant 
  in 
  the 
  lenticular 
  patches 
  of 
  

   pyrites 
  which 
  are 
  found 
  separating 
  the 
  Hamilton 
  shales 
  from 
  

   the 
  Genesee 
  at 
  nearly 
  every 
  exposure 
  of 
  this 
  horizon 
  from 
  

   Canandaigua 
  lake 
  to 
  the- 
  western 
  part 
  of 
  Genesee 
  county 
  and 
  

   perhaps 
  beyond. 
  

  

  The 
  overlying 
  shale 
  is 
  densely 
  black, 
  highly 
  bituminous 
  and 
  

   very 
  fissile, 
  with 
  lines 
  of 
  jointing 
  one 
  to 
  two 
  feet 
  apart 
  crossing 
  

   another 
  set 
  at 
  nearly 
  right 
  angles. 
  No 
  fossils 
  were 
  observed 
  

   except 
  a 
  few 
  plants. 
  This 
  layer 
  maintains 
  the 
  same 
  character 
  

   wherever 
  exposed 
  from 
  Canandaigua 
  lake 
  westward 
  across 
  the 
  

   salt 
  fields. 
  The 
  contrast 
  between 
  it 
  and 
  the 
  shales 
  below 
  becom- 
  

   ing 
  more 
  pronounced 
  in 
  that 
  direction 
  for 
  reasons 
  given 
  below. 
  

  

  About 
  fifteen 
  feet 
  of 
  the 
  shale 
  immediately 
  beneath 
  the 
  lime- 
  

   stone 
  is 
  quite 
  dark 
  bluish 
  gray, 
  fine 
  and 
  soft, 
  fissile 
  to 
  only 
  a 
  

   moderate 
  degree 
  and 
  not 
  at 
  all 
  bituminous. 
  It 
  contains 
  

   considerable 
  pyrites 
  in 
  nodules. 
  Fossils 
  are 
  somewhat 
  rare 
  in 
  

   the 
  upper 
  part 
  of 
  this 
  bed, 
  but 
  are 
  abundant 
  in 
  the 
  middle 
  and 
  

   lower 
  part. 
  The 
  fauna 
  is 
  distinctively 
  Hamilton, 
  though 
  the 
  

   number 
  of 
  species 
  is 
  not 
  large. 
  This 
  bed 
  may 
  be 
  traced 
  toward 
  

   the 
  west, 
  becoming 
  gradually 
  thinner.- 
  It 
  is 
  about 
  four 
  feet 
  

   thick 
  at 
  Moscow, 
  and 
  practically 
  disappears 
  in 
  the 
  vicinity 
  of 
  

   Darien, 
  where 
  the 
  light 
  colored 
  blue 
  gray 
  "Moscow 
  shale," 
  with 
  

   its 
  abundant 
  fossils 
  and 
  concretionary 
  layers, 
  may 
  be 
  seen 
  in 
  

   contact 
  with 
  the 
  black 
  Genesee 
  shale. 
  

  

  The 
  next 
  westward 
  exposures 
  of 
  the 
  Tully 
  horizon 
  are 
  in 
  the 
  

   ravines 
  and 
  rock 
  bluffs 
  along 
  the 
  shores 
  of 
  Canandaigua 
  lake, 
  

   where 
  for 
  several 
  miles 
  the 
  Genesee 
  shales 
  may 
  be 
  seen 
  resting, 
  

  

  