﻿Report 
  of 
  the 
  State 
  Geologist. 
  227 
  

  

  colored 
  and 
  are 
  not 
  more 
  than 
  100 
  feet 
  thick. 
  Flat 
  concretions 
  

   occur 
  and 
  fossils 
  are 
  less 
  abundant. 
  

  

  For 
  fifty 
  to 
  sixty 
  feet 
  above 
  the 
  upper 
  black 
  band 
  the 
  rock 
  is 
  

   principally 
  soft 
  shale, 
  with 
  a 
  few 
  thin 
  sandstones 
  and 
  many 
  con- 
  

   cretions, 
  in 
  which 
  casts 
  and 
  impressions 
  of 
  fossils 
  are 
  common. 
  

  

  Above 
  these 
  soft 
  shales 
  the 
  character 
  of 
  the 
  rock 
  changes 
  

   somewhat, 
  the 
  shales 
  becoming 
  harder, 
  and 
  flags 
  and 
  thin 
  sand- 
  

   stones 
  make 
  up 
  a 
  large 
  proportion 
  of 
  the 
  strata 
  for 
  about 
  250 
  

   feet, 
  in 
  which 
  Portage 
  fossils 
  may 
  at 
  rare 
  intervals 
  be 
  detected. 
  

  

  Bituminous 
  black 
  shale 
  occurs 
  at 
  intervals, 
  in 
  layers 
  usually 
  

   three 
  to 
  six 
  inches 
  thick. 
  

  

  The 
  upper 
  part 
  of 
  the 
  Portage 
  group 
  consists 
  of 
  beds 
  of 
  sand- 
  

   stones 
  from 
  a 
  few 
  inches 
  to 
  five 
  feet 
  thick 
  with 
  shale 
  between. 
  

  

  At 
  the 
  third 
  falls 
  in 
  the 
  Grimes 
  Gully, 
  at 
  Naples, 
  in 
  a 
  thin 
  layer 
  

   of 
  dark 
  soft 
  shale 
  several 
  species 
  of 
  Portage 
  fossils 
  have 
  been 
  found, 
  

   and 
  in 
  one 
  of 
  the 
  several 
  directly 
  overlying 
  layers 
  of 
  sandstone 
  

   near 
  the 
  brink 
  of 
  the 
  falls 
  there 
  are 
  many 
  impressions 
  and 
  casts 
  of 
  

   Liorhynchus 
  quadricostatus, 
  Atrypa 
  aspera 
  and 
  Amboccelia 
  umbo- 
  

   nata 
  var. 
  gregaria, 
  and 
  in 
  other 
  exposures 
  but 
  a 
  few 
  feet 
  above 
  

   this 
  horizon 
  Chemung 
  fossils 
  are 
  abundant. 
  

  

  From 
  the 
  bottom 
  of 
  the 
  lower 
  black 
  band 
  to 
  the 
  sandstone 
  

   where 
  these 
  fossils 
  occur 
  is 
  a 
  distance 
  of 
  599 
  feet, 
  which 
  is 
  the 
  

   thickness 
  of 
  the 
  Portage 
  group 
  in 
  the 
  Naples 
  valley. 
  The 
  transi- 
  

   tion 
  shales 
  between 
  the 
  lower 
  black 
  band 
  and 
  the 
  typical 
  Genesee 
  

   below 
  are 
  not 
  included 
  in 
  this 
  measurement. 
  

  

  At 
  Eock 
  Glen, 
  in 
  the 
  Oatka 
  valley, 
  the 
  - 
  Portage 
  rocks 
  are 
  a 
  

   little 
  more 
  than 
  800 
  feet 
  thick, 
  as 
  shown 
  in 
  an 
  accompanying 
  

   diagram. 
  

  

  Favorable 
  exposures 
  of 
  the 
  strata 
  of 
  the 
  Portage 
  epoch 
  may 
  be 
  

   seen 
  at 
  Belknap's 
  gully 
  and 
  at 
  Italy 
  hollow, 
  and 
  the 
  southern 
  

   part 
  of 
  Middlesex 
  valley 
  in 
  Yates 
  county. 
  

  

  At 
  Naples, 
  in 
  Ontario 
  county, 
  the 
  sections 
  in 
  Snyder's, 
  Parrish's 
  

   and 
  the 
  Grimes 
  gullies 
  together 
  include 
  the 
  whole 
  of 
  the 
  formation, 
  

   and 
  there 
  are 
  many 
  other 
  ravines 
  in 
  the 
  vicinity 
  where 
  good 
  out- 
  

   crops 
  occur. 
  

  

  The 
  Briggs 
  gully 
  and 
  other 
  ravines 
  about 
  the 
  head 
  of 
  Honeoye 
  

   lake 
  are 
  in 
  Portage 
  rocks, 
  also 
  the 
  upper 
  part 
  of 
  " 
  Mill 
  gull 
  " 
  near 
  

   the 
  foot 
  of 
  the 
  lake. 
  The 
  gorge 
  of 
  Whetstone 
  brook, 
  between 
  

  

  