﻿Upper 
  Ohio 
  and 
  Beaver 
  Rivers. 
  113 
  

  

  action 
  ; 
  that, 
  when 
  renewed 
  activity 
  had 
  been 
  given 
  the 
  cut- 
  

   ting 
  stream, 
  excavation 
  proceeded 
  without 
  break, 
  until 
  the 
  bot- 
  

   tom 
  of 
  the 
  now 
  buried 
  channel 
  was 
  reached. 
  A 
  more 
  careful 
  

   examination 
  of 
  the 
  inner 
  terraces 
  shows, 
  however, 
  that 
  to 
  some 
  

   extent 
  at 
  least, 
  the 
  prevailing 
  notions 
  regarding 
  them 
  are 
  not 
  

   correct. 
  There 
  are 
  points, 
  it 
  is 
  true, 
  where 
  the 
  current 
  descrip- 
  

   tions 
  seem, 
  in 
  some 
  features, 
  entirely 
  accurate, 
  but 
  it 
  is 
  believed 
  

   that 
  sufficient 
  is 
  now 
  known 
  to 
  show 
  that 
  the 
  broad 
  generaliza- 
  

   tions 
  that 
  have 
  been 
  drawn 
  are 
  incorrect. 
  

  

  Passing 
  up 
  the 
  Ohio 
  from 
  the 
  Pennsylvania 
  and 
  Ohio 
  State 
  

   line, 
  the 
  inner 
  terraces 
  alternate 
  from 
  side 
  to 
  side 
  of 
  the 
  stream, 
  

   and 
  no 
  appearance 
  of 
  an 
  included 
  rock 
  shelf 
  has 
  been 
  noticed 
  

   until 
  Raccoon 
  Creek 
  is 
  reached. 
  On 
  this 
  part 
  of 
  the 
  Ohio 
  the 
  

   inner 
  terraces, 
  so 
  far 
  as 
  observed, 
  are 
  made 
  up 
  bodily 
  of 
  allu- 
  

   vium, 
  the 
  gravel 
  appearing 
  to 
  extend 
  from 
  the 
  top 
  of 
  the 
  ter- 
  

   race 
  to 
  the 
  bottom 
  of 
  the 
  now 
  buried 
  channel. 
  

  

  At 
  the 
  mouth 
  of 
  Raccoon 
  Creek 
  we 
  find 
  the 
  alluvium 
  reach- 
  

   ing 
  to 
  the 
  height 
  of 
  the 
  " 
  third 
  " 
  terrace 
  (about 
  120 
  feet 
  above 
  

   river 
  level) 
  and 
  along 
  the 
  river 
  front 
  it 
  presents 
  an 
  unbroken 
  

   escarpment 
  of 
  gravel 
  and 
  bowlders. 
  Raccoon 
  Creek, 
  which 
  is 
  

   quite 
  a 
  rapid 
  stream, 
  shows, 
  however, 
  that 
  the 
  apparent 
  uni- 
  

   formity 
  in 
  terrace 
  material 
  is 
  a 
  mistake. 
  As 
  this 
  stream 
  

   emerges 
  from 
  the 
  narrow 
  valley 
  it 
  has 
  cut 
  for 
  itself, 
  into 
  the 
  

   trough 
  of 
  the 
  Ohio, 
  we 
  find 
  it 
  does 
  not 
  follow 
  its 
  natural 
  

   course, 
  but, 
  turning 
  abruptly 
  up 
  the 
  larger 
  stream, 
  it 
  has 
  cut 
  

   for 
  itself 
  a 
  narrow 
  canon 
  through 
  a 
  rather 
  massive 
  sandstone. 
  

   The 
  direct 
  course 
  of 
  the 
  stream 
  we 
  find 
  cut 
  off 
  by 
  the 
  alluvial 
  

   deposit, 
  and 
  evidently 
  the 
  old 
  channel 
  of 
  the 
  creek, 
  which 
  was 
  

   cut 
  when 
  the 
  now 
  buried 
  channel 
  of 
  the 
  Ohio 
  was 
  being 
  exca- 
  

   vated, 
  was, 
  on 
  the 
  coming 
  of 
  the 
  alluvium, 
  filled 
  to 
  the 
  terrace 
  

   level, 
  and 
  when 
  the 
  Ohio 
  re-excavated 
  its 
  channel 
  in 
  the 
  gravel, 
  

   Raccoon 
  Creek 
  was 
  turned 
  in 
  its 
  new 
  course 
  and 
  has 
  cut 
  the 
  

   channel 
  we 
  now 
  find, 
  which 
  is 
  in 
  no 
  way 
  comparable 
  in 
  size 
  

   with 
  the 
  valley 
  cut 
  for 
  many 
  miles 
  by 
  the 
  same 
  stream. 
  How 
  

   far 
  the 
  rock 
  here 
  underlying 
  the 
  terrace 
  extends 
  we 
  have 
  yet 
  

   no 
  means 
  of 
  knowing. 
  

  

  Crossing 
  the 
  Ohio 
  to 
  the 
  next 
  fragment 
  of 
  inner 
  terrace 
  we 
  

   come 
  to 
  the 
  point 
  where 
  the 
  inner 
  terraces 
  have 
  their 
  greatest 
  

   development 
  on 
  the 
  upper 
  Ohio. 
  On 
  both 
  sides 
  of 
  the 
  Beaver 
  

   river 
  the 
  terraces 
  attain 
  a 
  height 
  of 
  one 
  hundred 
  and 
  twenty 
  

   feet 
  above 
  stream 
  level. 
  On 
  the 
  lower, 
  or 
  Beaver, 
  side 
  it 
  

   extends 
  from 
  a 
  point 
  about 
  two 
  miles 
  below 
  the 
  mouth 
  of 
  the 
  

   Beaver 
  up 
  the 
  Ohio, 
  and 
  thence 
  up 
  the 
  Beaver 
  for 
  about 
  one 
  

   mile. 
  Where 
  Two 
  Mile 
  run 
  cuts 
  across 
  the 
  terrace 
  a 
  modern 
  

   channel 
  has 
  been 
  cut 
  through 
  the 
  ferriferous 
  limestone, 
  which 
  

   here 
  underlies 
  the 
  terrace 
  in 
  a 
  broad, 
  flat 
  bench. 
  How 
  far 
  this 
  

   rock 
  bench 
  extends 
  cannot 
  be 
  told. 
  It 
  at 
  no 
  point 
  shows 
  on 
  

  

  Am. 
  Jour. 
  Sol— 
  Third 
  Series, 
  Vol. 
  XLIX, 
  No. 
  290.— 
  Feb., 
  1895. 
  

  

  