﻿Western 
  Pennsylvania. 
  203 
  

  

  Beaver 
  river 
  route 
  will 
  be 
  strong. 
  If 
  high-level 
  terraces 
  occur, 
  

   as 
  they 
  doubtless 
  do, 
  ou 
  the 
  Ohio 
  between 
  the 
  mouth 
  of 
  the 
  

   Beaver 
  and 
  Wellsburg, 
  West 
  Virginia, 
  the 
  supposed 
  old 
  divide, 
  

   and 
  these 
  terraces 
  decline 
  totoard 
  the 
  mouth 
  of 
  the 
  Beaver, 
  i. 
  e. 
  

   contrary 
  to 
  the 
  present 
  stream, 
  then 
  the 
  demonstration 
  that 
  the 
  

   old 
  course 
  was 
  to 
  the 
  north 
  through 
  the 
  Beaver 
  valley 
  will 
  be 
  

   essentially 
  complete. 
  

  

  It 
  is 
  to 
  be 
  hoped 
  that 
  Mr. 
  Foghay, 
  who 
  is 
  practically 
  on 
  the 
  

   ground, 
  will 
  pursue 
  to 
  a 
  demonstration 
  the 
  hypothesis 
  he 
  has 
  

   already 
  rendered 
  so 
  highly 
  probable. 
  

  

  As 
  to 
  the 
  course 
  which 
  this 
  old 
  river 
  pursued 
  north 
  of 
  the 
  

   moraine 
  on 
  the 
  Beaver 
  (assuming 
  that 
  it 
  took 
  this 
  course) 
  — 
  

   whether 
  along 
  the 
  present 
  route 
  of 
  the 
  Mahoning 
  or 
  that 
  of 
  

   the 
  Shenango 
  — 
  there 
  seems 
  to 
  be 
  no 
  demonstrative 
  evidence. 
  

   None 
  of 
  Mr. 
  Foshay's 
  data 
  bear 
  definitely 
  on 
  this 
  point. 
  The 
  

   Shenango 
  valley 
  all 
  the 
  way 
  from 
  its 
  mouth, 
  7-8 
  miles 
  north 
  

   of 
  where 
  the 
  high-terrace 
  is 
  lost 
  under 
  the 
  moraine, 
  to 
  the 
  

   Pymatuning 
  swamp 
  on 
  the 
  Erie 
  divide 
  where 
  it 
  connects 
  with 
  

   the 
  valley 
  of 
  Ashtabula 
  creek 
  flowing 
  into 
  Lake 
  Erie, 
  is 
  

   broader 
  than 
  that 
  of 
  the 
  Mahoning 
  from 
  its 
  mouth 
  to 
  the 
  Erie 
  

   divide 
  near 
  Warren, 
  Ohio 
  ; 
  its 
  bluffs 
  are 
  less 
  abrupt 
  and 
  its 
  

   general 
  aspect 
  that 
  of 
  a 
  valley 
  older 
  as 
  well 
  as 
  larger 
  than 
  that 
  

   of 
  the 
  Mahoning. 
  Moreover 
  the 
  lower 
  Mahoning 
  valley 
  be- 
  

   comes 
  very 
  narrow 
  in 
  the 
  'vicinity 
  of 
  Lowell 
  ville, 
  Ohio, 
  having 
  

   abrupt 
  bluffs 
  with 
  a 
  breadth 
  at 
  base 
  of 
  but 
  about 
  one 
  fourth 
  

   mile, 
  which 
  is 
  too 
  narrow 
  to 
  make 
  it 
  probable 
  that 
  it 
  is 
  a 
  con- 
  

   tinuation 
  of 
  the 
  old 
  river 
  under 
  consideration, 
  whose 
  breadth 
  

   above 
  is 
  much 
  greater 
  and 
  whose 
  slopes 
  are 
  more 
  worn 
  and 
  

   receding. 
  The 
  narrowing 
  at 
  this 
  point 
  fits 
  well 
  the 
  hypothesis 
  

   that 
  here 
  was 
  the 
  preglacial 
  divide 
  between 
  a 
  stream 
  running 
  

   northwest 
  into 
  the 
  Grand 
  river 
  basin 
  and 
  one 
  running 
  south- 
  

   east 
  to 
  join 
  the 
  old 
  river 
  under 
  discussion 
  at 
  the 
  present 
  mouth 
  

   of 
  the 
  Mahoning. 
  Furthermore, 
  the 
  main 
  preglacial 
  valley 
  of 
  

   the 
  Grand 
  river 
  basin 
  seems 
  to 
  have 
  entered, 
  not 
  from 
  the 
  

   southeast 
  along 
  the 
  lower 
  Mahoning 
  but 
  from 
  the 
  south 
  along 
  

   the 
  upper 
  Mahoning 
  from 
  the 
  direction 
  of 
  Alliance, 
  Ohio, 
  

   there 
  being 
  a 
  comparatively 
  low 
  belt 
  several 
  miles 
  wide 
  along 
  

   the 
  upper 
  (north 
  flowing) 
  part 
  of 
  the 
  Mahoning, 
  with 
  low 
  

   bluffs 
  and 
  a 
  gradual 
  rise 
  both 
  to 
  the 
  east 
  and 
  the 
  west 
  of 
  the 
  

   river. 
  The 
  relative 
  elevations 
  of 
  the 
  present 
  divides 
  on 
  the 
  

   Mahoning 
  and 
  Shenango 
  routes 
  respectively, 
  do 
  not 
  help 
  us 
  

   much 
  in 
  this 
  question, 
  since, 
  in 
  the 
  first 
  place, 
  we 
  cannot 
  trace, 
  

   or 
  at 
  least 
  have 
  not 
  traced, 
  the 
  terraces 
  which 
  mark 
  the 
  old 
  

   river 
  bed, 
  — 
  the 
  present 
  surface 
  divide 
  and 
  the 
  present 
  rock 
  

   divide 
  being 
  matters 
  of 
  more 
  recent 
  formation 
  — 
  and, 
  in 
  the 
  

   second 
  place, 
  an 
  eastward 
  differential 
  uplift 
  is 
  known 
  to 
  have 
  

   taken 
  place. 
  The 
  uplift 
  referred 
  to 
  is 
  well 
  shown 
  by 
  the 
  

  

  