﻿120 
  H. 
  It. 
  Sice 
  — 
  Inner 
  Gorge 
  Terraces 
  , 
  etc. 
  

  

  If 
  we 
  examine 
  the 
  structure 
  of 
  the 
  terraces 
  as 
  revealed 
  by 
  

   excavations 
  in 
  the 
  midst 
  of 
  them, 
  we 
  find 
  them 
  in 
  harmony 
  

   with 
  the 
  character 
  of 
  the 
  filling 
  of 
  the 
  buried 
  channel. 
  A 
  

   well 
  at 
  Beaver 
  Falls 
  commenced 
  at 
  the 
  top 
  of 
  the 
  terrace, 
  and 
  

   excavated 
  over 
  eight} 
  r 
  feet 
  to 
  rock, 
  showed 
  first 
  a 
  few 
  feet 
  of 
  

   coarse 
  material, 
  followed 
  by 
  coarse 
  gravel, 
  which 
  in 
  turn 
  grew 
  

   finer 
  until 
  it 
  corresponded 
  with 
  the 
  gravel 
  found 
  in 
  the 
  buried 
  

   channel. 
  At 
  Beaver, 
  after 
  passing 
  through 
  a 
  few 
  feet 
  of 
  the 
  

   coarser 
  material, 
  the 
  same 
  is 
  true, 
  reaching, 
  as 
  we 
  know 
  from 
  

   old 
  wells, 
  to 
  the 
  present 
  level 
  of 
  the 
  Ohio. 
  At 
  Georgetown, 
  

   after 
  passing 
  through 
  eight 
  feet, 
  no 
  more 
  u 
  bowlders" 
  were 
  

   found 
  to 
  present 
  river 
  level. 
  

  

  It 
  is 
  not 
  intended 
  to 
  convey 
  the 
  impression 
  that 
  the 
  terraces, 
  

   or 
  rather 
  the 
  alluvial 
  portion 
  of 
  them, 
  are 
  made 
  up 
  bodily 
  of 
  

   the 
  finer 
  material, 
  for 
  it 
  is 
  believed 
  there 
  are 
  evidences 
  from 
  

   the 
  escarpment 
  that 
  in 
  the 
  middle 
  of 
  the 
  valleys 
  the 
  upper 
  half 
  

   of 
  the 
  filling 
  is 
  coarser 
  than 
  the 
  average, 
  but 
  it 
  is 
  evident 
  the 
  

   stream 
  depositing 
  the 
  alluvium 
  had 
  by 
  no 
  means 
  the 
  transport- 
  

   ing 
  power 
  heretofore 
  assigned 
  it. 
  In 
  the 
  refilling 
  of 
  the 
  inner 
  

   gorge 
  the 
  depositing 
  stream 
  was 
  not 
  a 
  torrential 
  current, 
  but 
  at 
  

   first 
  was 
  quite 
  sluggish, 
  depositing 
  fine 
  silt 
  only, 
  gradually 
  in- 
  

   creasing 
  in 
  carrying 
  power 
  until 
  the 
  whole 
  of 
  the 
  inner 
  alluvium 
  

   was 
  deposited, 
  but 
  apparently 
  at 
  no 
  time 
  of 
  sufficient 
  eroding 
  

   power 
  to 
  remove 
  the 
  deposit 
  just 
  previously 
  made.* 
  

  

  Beaver, 
  Pa., 
  Jan. 
  5, 
  1895. 
  

  

  *The 
  literature 
  of 
  subject 
  is 
  quite 
  scattered, 
  the 
  principal 
  papers 
  are: 
  — 
  

   T. 
  C. 
  Chamberlin, 
  U. 
  S. 
  G-eol. 
  Survey, 
  Bull. 
  58, 
  pp. 
  24-37 
  ; 
  Bull. 
  Geol. 
  Soc. 
  A., 
  

   vol. 
  i, 
  pp. 
  472-473; 
  p. 
  479; 
  this 
  Journal, 
  vol. 
  xlv, 
  p. 
  195; 
  vol. 
  xlvii, 
  x>. 
  247. 
  

   G. 
  F. 
  Wright, 
  U. 
  S. 
  Geol. 
  Survey. 
  Bull. 
  58, 
  pp. 
  76-78, 
  pp. 
  81-86; 
  Ice~Age 
  in 
  

   N. 
  A., 
  pp. 
  287-289, 
  pp. 
  335-339; 
  this 
  Journal, 
  vol. 
  xliv, 
  pp. 
  368-371; 
  xlvii, 
  p. 
  

   161; 
  Am. 
  Geol, 
  vol. 
  xi, 
  pp. 
  195-199. 
  Dr. 
  Alfred 
  T. 
  King, 
  " 
  Ancient 
  Alluvium 
  

   of 
  the 
  Ohio 
  Yalley 
  and 
  its 
  Tributaries," 
  January, 
  1854. 
  Frank 
  Leverett 
  this 
  

   Journal, 
  vol. 
  xlii, 
  p. 
  210; 
  vol. 
  xlvii, 
  p. 
  247. 
  P. 
  Max 
  Foshay, 
  this 
  Journal, 
  vol. 
  xl, 
  

   p. 
  401 
  ; 
  Bull. 
  G. 
  S. 
  A., 
  vol. 
  ii, 
  p. 
  457. 
  I. 
  C. 
  White, 
  Second 
  Geol. 
  Survey 
  Penna., 
  

   vol. 
  Q, 
  pp. 
  10-14; 
  vol. 
  QQ, 
  pp. 
  10-12; 
  vol. 
  QQQ, 
  pp. 
  17-18. 
  J. 
  J. 
  Stevenson, 
  

   Second 
  Geol. 
  Sur. 
  Penna., 
  vol. 
  K, 
  pp. 
  11-19. 
  J. 
  P. 
  Leslie, 
  Sec. 
  Geol. 
  Sur. 
  Penna,, 
  

   vol. 
  Q, 
  pp. 
  xxv. 
  B. 
  C. 
  Jillson, 
  Trans, 
  of 
  Academy 
  Sci. 
  and 
  Art. 
  Pittsburg, 
  vol. 
  i, 
  

   pp. 
  1-25. 
  E. 
  W". 
  Claypole, 
  Trans. 
  Geol. 
  Soc. 
  Edinburgh, 
  1887, 
  p. 
  42. 
  R. 
  R. 
  

   Eice, 
  Bull. 
  Geol. 
  Soc. 
  Am., 
  v^l. 
  ii, 
  p. 
  457 
  ; 
  Science, 
  vol. 
  xxii, 
  p. 
  170. 
  

  

  