﻿NIAGARA 
  FALLS 
  AND 
  VICINITY 
  1 
  23 
  

  

  indicate 
  a 
  high 
  degree 
  of 
  saHnity 
  of 
  the 
  waters 
  of 
  the 
  early 
  Medina 
  

   sea. 
  If 
  such 
  was 
  the 
  case, 
  it 
  may 
  have 
  been 
  accompanied 
  by 
  a 
  more 
  

   or 
  less 
  arid 
  climate, 
  which 
  favored 
  the 
  concentration 
  of 
  the 
  sea 
  

   water. 
  Thick 
  beds 
  of 
  terrigenous 
  material 
  accumulated 
  in 
  the 
  cen- 
  

   ter 
  of 
  the 
  Medina 
  basin 
  reaching 
  in 
  the 
  Niagara 
  region 
  a 
  thickness 
  

   of 
  over 
  a 
  thousand 
  feet. 
  These 
  early 
  deposits 
  probably 
  did 
  not 
  ex- 
  

   tend 
  far 
  west 
  for, 
  though 
  in 
  northern 
  Ohio 
  and 
  Michigan, 
  Medina 
  

   beds 
  from 
  50 
  to 
  100 
  feet 
  or 
  more 
  in 
  thickness 
  are 
  known, 
  these 
  are 
  

   probably 
  to 
  be 
  correlated 
  with 
  the 
  upper 
  Medina 
  of 
  the 
  Niagara 
  

   region. 
  

  

  Toward 
  the 
  close 
  of 
  the 
  Aledina 
  epoch, 
  the 
  Siluric 
  sea 
  had 
  en- 
  

   croached 
  on 
  the 
  lands 
  to 
  such 
  an 
  extent 
  as 
  to 
  effect 
  a 
  junction 
  with 
  

   the 
  Medina 
  basin, 
  whereupon 
  normal 
  marine 
  conditions 
  were 
  again 
  

   established. 
  This 
  is 
  indicated 
  by 
  the 
  marine 
  fauna 
  and 
  flora 
  which 
  

   characterize 
  the 
  upper 
  Medina 
  beds. 
  The 
  first 
  deposit 
  in 
  this 
  re- 
  

   gion, 
  on 
  the 
  reestablishment 
  of 
  normal 
  marine 
  conditions, 
  was 
  the 
  

   white 
  quartzose 
  sandstone 
  which 
  caps 
  the 
  red 
  shale 
  of 
  the 
  lower 
  

   series. 
  Mud 
  and 
  sand 
  now 
  alternated, 
  indicating 
  an 
  oscilla- 
  

   tion 
  of 
  conditions 
  with 
  numerous 
  changes 
  in 
  the 
  currents 
  which 
  

   distributed 
  the 
  detrital 
  material. 
  Thin 
  beds 
  of 
  limestones 
  also 
  

   formed 
  at 
  rare 
  intervals, 
  chiefly 
  from 
  the 
  growth 
  of 
  bryozoans 
  in 
  

   favorable 
  locaHties. 
  In 
  the 
  Bay 
  of 
  New 
  York 
  the 
  waters 
  continued 
  

   moderately 
  shallow, 
  as 
  shown 
  by 
  the 
  well 
  developed 
  cross-bedding 
  

   structure 
  in 
  the 
  sandstones. 
  At 
  intervals 
  large 
  tracts 
  seem 
  to 
  have 
  

   been 
  laid 
  bare 
  on 
  the 
  retreat 
  of 
  the 
  tide, 
  as 
  indicated 
  by 
  the 
  wave 
  

   marks 
  and 
  other 
  shore 
  features 
  which 
  give 
  the 
  surfaces 
  of 
  some 
  

   Medina 
  sandstone 
  slabs 
  such 
  a 
  remarkable 
  resemblance 
  to 
  a 
  modern 
  

   sand 
  beach 
  exposed 
  by 
  the 
  ebbing 
  tide. 
  In 
  fact, 
  we 
  may 
  not 
  in- 
  

   aptly 
  compare 
  this 
  stage 
  of 
  the 
  Siluric 
  bay 
  of 
  New 
  York 
  with 
  the 
  

   upper 
  end 
  of 
  the 
  modern 
  bay 
  of 
  Fundy, 
  where 
  the 
  red 
  sands 
  and 
  

   muds 
  are 
  laid 
  bare 
  for 
  miles 
  on 
  the 
  retreat 
  of 
  the 
  tide. 
  

  

  After 
  the 
  last 
  sandstone 
  bed 
  of 
  the 
  Medina 
  stage 
  had 
  been 
  de- 
  

   posited, 
  the 
  water 
  probably 
  became 
  purer 
  and 
  deeper, 
  and 
  the 
  6 
  

   feet 
  of 
  Clinton 
  shales 
  were 
  laid 
  down 
  in 
  the 
  Niagara 
  region. 
  In 
  

   the 
  eastern 
  part 
  of 
  the 
  Bay 
  of 
  New 
  York, 
  sandstones 
  were 
  deposited 
  

   even 
  during 
  the 
  CHnton 
  epoch, 
  while 
  the 
  conditions 
  favoring 
  the 
  

   deposition 
  of 
  Hmestone 
  existed 
  only 
  during 
  the 
  short 
  interval 
  in 
  

  

  