﻿128 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  and 
  the 
  greater 
  part 
  of 
  the 
  interior 
  Siluric 
  sea 
  into 
  a 
  vast 
  partially^ 
  

   or 
  entirely 
  inclosed 
  basin. 
  This 
  elevation 
  appears 
  to 
  have 
  been 
  

   accompanied 
  by 
  climatic 
  desiccation 
  which 
  brought 
  about 
  

   a 
  rapid 
  evaporation 
  of 
  the 
  waters 
  and 
  a 
  consequent 
  increase 
  in 
  

   salinity. 
  Thus 
  this 
  great 
  interior 
  water 
  .body 
  was 
  changed 
  from 
  a 
  

   richly 
  peopled 
  mediterranean, 
  to 
  a 
  lifeless 
  body 
  of 
  intensely 
  saline 
  

   water, 
  a 
  veritable 
  Dead 
  sea. 
  As 
  the 
  concentration 
  of 
  the 
  brine 
  con- 
  

   tinued, 
  deposition 
  of 
  gypsum 
  began, 
  and 
  later 
  on 
  the 
  extensive 
  beds 
  

   of 
  rock 
  salt 
  of 
  this 
  formation 
  were 
  laid 
  down. 
  Some 
  of 
  these 
  salt 
  

   beds 
  in 
  Michigan 
  are 
  reported 
  to 
  be 
  a 
  thousand 
  feet 
  thick,, 
  

   but 
  none 
  of 
  the 
  New 
  York 
  beds 
  approach 
  this 
  thickness. 
  The 
  clas- 
  

   tic 
  strata 
  of 
  the 
  Salina 
  series 
  were 
  probably 
  derived 
  from 
  the 
  de- 
  

   struction 
  of 
  the 
  sediments 
  which 
  were 
  formed 
  during 
  the 
  early 
  

   periods 
  of 
  the 
  Siluric 
  and 
  during 
  preceding 
  periods. 
  This 
  would 
  

   account 
  for 
  the 
  presence 
  of 
  limestone 
  beds 
  in 
  deposits 
  formed 
  in 
  a. 
  

   lifeless 
  sea. 
  All 
  these 
  limestones 
  were 
  more 
  or 
  less 
  mixed 
  with 
  

   clayey 
  sediments; 
  they 
  may 
  in 
  fact 
  be 
  regarded 
  as 
  consolidated 
  ar- 
  

   gillo-calcareous 
  muds 
  derived 
  from 
  older 
  limestones 
  and 
  shales.- 
  

   This 
  is 
  the 
  character 
  of 
  the 
  Waterlime 
  and 
  Manlius 
  limestone 
  which 
  

   succeed 
  the 
  Salina 
  beds, 
  and 
  which, 
  though 
  fossiliferous, 
  could 
  have- 
  

   no 
  other 
  source 
  of 
  origin 
  than 
  preexisting 
  limestone 
  beds. 
  

  

  The 
  Waterlime 
  has 
  been 
  regarded 
  as 
  a 
  fresh-water 
  formation. 
  It 
  

   is 
  more 
  likely 
  however 
  that 
  it 
  represents 
  a 
  return 
  of 
  marine 
  condi- 
  

   tions 
  through 
  the 
  opening 
  of 
  channels 
  between 
  this 
  interior 
  basin 
  

   and 
  the 
  ocean 
  at 
  large. 
  This 
  is 
  indicated 
  by 
  the 
  fauna, 
  which 
  in- 
  

   cludes 
  undoubted 
  marine 
  forms. 
  Whether 
  this 
  connection 
  was. 
  

   through 
  the 
  old 
  northern 
  channel, 
  or 
  whether 
  a 
  new 
  channel 
  toward 
  

   the 
  east 
  was 
  opened 
  is 
  not 
  apparent. 
  The 
  former 
  is 
  indicated 
  by 
  the 
  

   character 
  of 
  the 
  Manlius 
  limestone 
  which 
  succeeds 
  the 
  Waterlime,. 
  

   and 
  which 
  in 
  the 
  Niagara 
  region 
  has 
  features 
  associating 
  it 
  with 
  

   the 
  corresponding 
  deposits 
  of 
  Ohio, 
  Michigan 
  and 
  Ontario, 
  rather 
  

   than 
  its 
  eastern 
  equivalents. 
  Whatever 
  the 
  nature 
  of 
  the 
  transgres- 
  

   sion 
  of 
  the 
  sea 
  which 
  took 
  place 
  in 
  the 
  late 
  Siluric, 
  it 
  was 
  not 
  of 
  

   long 
  duration. 
  The 
  epoch 
  of 
  the 
  Manlius 
  limestone 
  and 
  with 
  it 
  

   the 
  Siluric 
  era 
  were 
  brought 
  to 
  a 
  close 
  with 
  the 
  withdrawal 
  of 
  all 
  

   the 
  waters 
  from 
  this 
  portion 
  of 
  the 
  continent, 
  which 
  thereafter 
  for 
  

  

  