﻿Report 
  of 
  tse 
  State 
  Geologist 
  229 
  

  

  At 
  the 
  depth 
  of 
  119 
  feet 
  below 
  the 
  surface 
  in 
  the 
  Livonia 
  

   shaft 
  the 
  top 
  of 
  the 
  Genesee 
  group 
  was 
  reached. 
  This 
  group 
  is 
  

   161 
  feet 
  thick, 
  at 
  this 
  point 
  and 
  may 
  be 
  divided 
  into 
  the 
  upper 
  

   Genesee, 
  the 
  Styliola 
  band 
  and 
  the 
  lower 
  Genesee. 
  

  

  The 
  upper 
  Genesee 
  beds 
  are 
  bluish 
  shales, 
  quite 
  dark 
  except 
  

   when 
  exposed 
  to 
  sunshine, 
  which 
  gives 
  them 
  a 
  much 
  lighter 
  

   color. 
  Thin 
  layers 
  of 
  bituminous 
  black 
  shale 
  occur 
  every 
  few 
  

   feet. 
  Concretionary 
  layers 
  and 
  layers 
  of 
  separate 
  concretions, 
  

   generally 
  not 
  very 
  persistent, 
  though 
  some 
  of 
  them 
  continue 
  for 
  

   a 
  long 
  distance, 
  may 
  be 
  seen 
  whenever 
  these 
  shales 
  are 
  exposed. 
  

   Single 
  spherical 
  concretions 
  of 
  all 
  sizes 
  and 
  flattened 
  septaria 
  

   (" 
  turtle 
  stones 
  ") 
  are 
  common. 
  Fossils 
  are 
  quite 
  abundant 
  in 
  the 
  

   blue 
  shales 
  and 
  the 
  concretions. 
  The 
  black 
  layers 
  rarely 
  contain 
  

   other 
  than 
  fish 
  and 
  plant 
  remains. 
  

  

  In 
  the 
  vicinity 
  of 
  Canandaigua 
  lake 
  the 
  Genesee 
  division 
  

   includes 
  a 
  bed 
  of 
  olive 
  and 
  bluish 
  soft 
  shales 
  about 
  twenty 
  

   feet 
  thick, 
  which 
  lies 
  immediately 
  below 
  the 
  lower 
  black 
  band 
  

   of 
  the 
  Portage 
  group 
  and 
  contains 
  both 
  Portage 
  and 
  Genesee 
  

   fossils. 
  Zunulicardium 
  fragile 
  is 
  v 
  however, 
  the 
  most 
  abundant 
  

   form. 
  These 
  " 
  transition 
  shales 
  " 
  either 
  thin 
  out 
  or 
  change 
  char- 
  

   acter 
  in 
  the 
  Genesee 
  valley 
  and 
  westward 
  and 
  are 
  not 
  seen. 
  

  

  The 
  Styliola 
  hand 
  occupies 
  a 
  position 
  near 
  the 
  middle 
  of 
  the 
  

   Genesee 
  shales 
  and 
  extends 
  from 
  Middlesex, 
  in 
  Yates 
  county, 
  to 
  

   Darien, 
  in 
  Genesee 
  county, 
  and 
  probably 
  further 
  in 
  both 
  direc- 
  

   tions. 
  It 
  is 
  a 
  band 
  of 
  thin 
  limestones 
  and 
  calcareous 
  shales 
  that 
  

   are 
  easily 
  recognized 
  after 
  a 
  slight 
  examination 
  and 
  are 
  so 
  peculiar 
  

   and 
  persistent 
  in 
  character 
  and 
  so 
  frequently 
  exposed 
  as 
  to 
  con- 
  

   stitute 
  a 
  valuable 
  landmark 
  in 
  the 
  geology 
  of 
  the 
  salt 
  fields. 
  

   As 
  exposed 
  along 
  the 
  shores 
  of 
  Canandaigua 
  lake, 
  this 
  band 
  con- 
  

   sists 
  of 
  several 
  layers 
  of 
  dark 
  gray 
  to 
  black 
  or 
  bluish 
  limestone 
  

   two 
  to 
  four 
  inches 
  thick, 
  which 
  occur 
  at 
  irregular 
  intervals 
  

   through 
  fifteen 
  to 
  eighteen 
  feet 
  of 
  black 
  shale. 
  One 
  or 
  more 
  of 
  

   these 
  thin 
  limestones 
  presents 
  a 
  nodular 
  or 
  concretionary 
  appear- 
  

   ance, 
  and 
  with 
  the 
  manner 
  in 
  which 
  the 
  hard 
  and 
  apparently 
  

   sandy 
  shale 
  is 
  bent 
  over 
  the 
  irregular 
  surface 
  forms 
  a 
  noticeable 
  

   feature 
  at 
  every 
  exposure 
  of 
  this 
  horizon. 
  

  

  Both 
  the 
  limestones 
  and 
  the 
  adjacent 
  calcareous 
  shales 
  are 
  

   almost 
  entirely 
  composed 
  of 
  the 
  acicular 
  shells 
  of 
  the 
  small 
  

   pteropod 
  Styliola 
  fissurella^ 
  which 
  J. 
  M. 
  Clarke, 
  in 
  Bulletin 
  16, 
  U. 
  S. 
  

  

  