﻿THEORY 
  OF 
  LAKE-BASINS. 
  487 
  

  

  Now, 
  if 
  we 
  suppose 
  the 
  Lago 
  di 
  Orta 
  to 
  have 
  been 
  excavated 
  by 
  a 
  

   glacier, 
  we 
  must 
  account, 
  as 
  in 
  the 
  case 
  of 
  the 
  western 
  arm 
  of 
  

   Como, 
  for 
  the 
  ridgy 
  outline 
  of 
  the 
  felsite 
  hills, 
  which 
  could 
  not 
  

   have 
  resisted 
  so 
  great 
  a 
  grinding 
  force. 
  We 
  must 
  determine 
  which 
  

   was 
  the 
  direction 
  of 
  the 
  glacier 
  in 
  order 
  to 
  see 
  how 
  far 
  it 
  would 
  

   be 
  likely 
  to 
  exercise 
  a 
  scooping 
  force. 
  

  

  It 
  either 
  descended 
  by 
  the 
  Val 
  Strona, 
  or 
  was 
  an 
  offshoot 
  from 
  the 
  

   great 
  Ticino 
  glacier, 
  coming 
  up 
  the 
  valley 
  down 
  which 
  the 
  Strona 
  

   torrent 
  now 
  descends, 
  and 
  which 
  appears 
  like 
  a 
  prolongation 
  of 
  the 
  

   valley 
  of 
  the 
  Lake 
  of 
  Orta. 
  The 
  difficulties 
  in 
  the 
  former 
  view 
  will 
  

   be 
  seen 
  when 
  I 
  speak 
  of 
  the 
  Val 
  Strona. 
  If 
  the 
  latter 
  is 
  correct, 
  

   we 
  have 
  to 
  account 
  for 
  this 
  extraordinary 
  offshoot, 
  for 
  its 
  ascent 
  up 
  

   some 
  500 
  feet, 
  and 
  for 
  its 
  then 
  scooping 
  out 
  the 
  lake-basin. 
  

  

  From 
  the 
  northern 
  extremity 
  of 
  the 
  Lago 
  di 
  Orta, 
  I 
  ascended 
  to 
  

   the 
  head 
  of 
  the 
  Val 
  Strona 
  and 
  crossed 
  to 
  Vogogna, 
  in 
  the 
  Val 
  

   d'Ossola, 
  and 
  then 
  drove 
  to 
  Ponte 
  Grande, 
  in 
  the 
  Val 
  Anzasca. 
  

   Hence 
  I 
  crossed 
  to 
  Fobello 
  and 
  descended 
  the 
  Val 
  Mastalone 
  to 
  its 
  

   junction 
  at 
  Varallo 
  with 
  the 
  Val 
  Sesia, 
  ascended 
  that 
  valley 
  to 
  its 
  

   head, 
  crossed 
  over 
  to 
  Gressonay, 
  in 
  the 
  Val 
  de 
  Lys, 
  and 
  thence 
  to 
  

   the 
  head 
  of 
  the 
  Val 
  d'Ayas, 
  from 
  which 
  I 
  reached 
  Zermatt 
  by 
  the 
  

   Schwartz-Thor. 
  The 
  results 
  of 
  this 
  journey, 
  which 
  occupied 
  a 
  week, 
  

   may 
  be 
  summed 
  up 
  very 
  shortly 
  ; 
  but 
  they 
  have, 
  I 
  conceive, 
  an 
  

   important 
  bearing 
  on 
  the 
  point 
  at 
  issue. 
  

  

  The 
  Val 
  Strona 
  is 
  everywhere 
  a 
  narrow 
  V-shaped 
  valley, 
  in 
  

   places 
  almost 
  a 
  gorge. 
  There 
  is 
  abundant 
  evidence 
  that 
  a 
  glacier 
  

   has 
  descended 
  it 
  ; 
  but 
  without 
  materially 
  altering 
  the 
  characteristic 
  

   outlines 
  of 
  a 
  valley 
  formed 
  by 
  rain 
  and 
  rivers. 
  The 
  Val 
  Anzasca 
  is 
  

   also 
  a 
  narrow 
  V-valley, 
  commonly 
  with 
  a 
  gorge 
  at 
  the 
  bottom 
  ; 
  yet 
  

   a 
  glacier 
  has 
  evidently 
  descended 
  it 
  while 
  its 
  form 
  was 
  much 
  as 
  now, 
  

   and 
  the 
  ice-marks 
  may 
  here 
  and 
  there 
  be 
  detected 
  at 
  no 
  great 
  height 
  

   above 
  the 
  stream. 
  

  

  The 
  Val 
  Mastalone 
  is 
  throughout 
  of 
  the 
  above 
  form, 
  everywhere 
  

   narrow, 
  in 
  most 
  places 
  a 
  mere 
  glen 
  with 
  little 
  or 
  no 
  level 
  land 
  by 
  

   the 
  side 
  of 
  the 
  stream 
  ; 
  yet 
  in 
  places 
  the 
  ice-marks 
  may 
  be 
  detected 
  

   only 
  a 
  few 
  feet 
  above 
  the 
  water, 
  as 
  for 
  example 
  about 
  12 
  kilometres 
  

   above 
  Varallo. 
  The 
  main 
  valley 
  of 
  the 
  Sesia 
  above 
  that 
  town 
  

   generally 
  resembles 
  that 
  of 
  the 
  Val 
  Mastalone, 
  except 
  that 
  there 
  is 
  

   often, 
  though 
  not 
  always, 
  a 
  small 
  strip 
  of 
  level 
  land 
  by 
  the 
  stream. 
  

   It 
  has 
  been 
  filled 
  by 
  a 
  glacier, 
  which 
  has 
  left 
  some 
  of 
  its 
  most 
  

   conspicuous 
  traces 
  on 
  an 
  ice-worn 
  mound 
  of 
  rock 
  at 
  Scopello, 
  

   perhaps 
  300 
  feet 
  high, 
  on 
  one 
  side 
  of 
  which 
  goes 
  the 
  road, 
  on 
  the 
  

   other 
  the 
  river. 
  

  

  Among 
  the 
  magnificent 
  scenery 
  at 
  the 
  head 
  of 
  this 
  valley, 
  under 
  

   the 
  cliffs 
  of 
  Monte 
  Rosa, 
  I 
  was 
  again 
  and 
  again 
  struck 
  with 
  the 
  

   absence 
  of 
  any 
  relation 
  between 
  the 
  principal 
  features 
  of 
  the 
  scenery 
  

   and 
  the 
  direction 
  of 
  motion 
  of 
  the 
  glaciers. 
  Surely 
  here, 
  if 
  anywhere, 
  

   the 
  projecting 
  buttresses 
  of 
  rock, 
  which 
  at 
  times 
  almost 
  bar 
  the 
  

   valley, 
  should 
  have 
  been 
  ground 
  away 
  by 
  the 
  enormous 
  pressure 
  to 
  

   which 
  they 
  have 
  been 
  subjected; 
  but 
  though 
  rounded 
  and 
  worn 
  

   smooth, 
  they 
  still 
  remain 
  as 
  barriers, 
  suggesting 
  irresistibly 
  the 
  con- 
  

  

  