﻿OF 
  THE 
  LAKE-BASINS 
  OF 
  CUMBERLAND. 
  99 
  

  

  of 
  the 
  Derwent 
  valley 
  above 
  Seathwaite, 
  and 
  having 
  no 
  other 
  out- 
  

   ward 
  push 
  but 
  that 
  due 
  to 
  gravitation 
  down 
  the 
  two-and-a-half-mile 
  

   slope 
  from 
  Allen 
  Crags 
  to 
  Seathwaite, 
  and 
  to 
  molecular 
  gravi- 
  

   tation 
  throughout 
  its 
  length, 
  we 
  might 
  be 
  inclined 
  to 
  question 
  

   the 
  possibility 
  of 
  its 
  moving 
  over 
  the 
  thirteen 
  miles 
  of 
  flat 
  ground 
  

   and 
  scooping 
  out 
  lake-basins 
  in 
  its 
  course. 
  But 
  just 
  as 
  the 
  river 
  

   Derwent 
  now 
  receives 
  very 
  many 
  tributaries, 
  some 
  as 
  large 
  as 
  

   itself, 
  from 
  the 
  valleys 
  and 
  mountains 
  on 
  either 
  side, 
  and 
  yet 
  does 
  

   not 
  occupy 
  a 
  much 
  wider 
  channel, 
  but 
  acquires 
  a 
  faster 
  flow 
  and 
  

   greater 
  power 
  of 
  moving 
  material 
  onwards 
  with 
  it, 
  so 
  did 
  the 
  old 
  

   Borrowdale 
  glacier, 
  the 
  former 
  representative 
  of 
  the 
  Derwent, 
  

   receive 
  additional 
  impulse 
  from 
  the 
  numerous 
  glacier 
  sheets 
  shed 
  

   off 
  the 
  mountains 
  on 
  either 
  side 
  and 
  down 
  the 
  tributary 
  valleys. 
  

   Let 
  us 
  see 
  what 
  this 
  additional 
  impulse 
  really 
  means. 
  Above 
  the 
  

   village 
  of 
  Rosthwaite 
  there 
  met 
  several 
  large 
  ice-streams. 
  The 
  

   Derwent 
  glacier 
  proper 
  received 
  reinforcement 
  from 
  ice 
  coming 
  

   down 
  from 
  Sty 
  Head, 
  out 
  of 
  Sourmilk 
  Comb 
  between 
  Grey 
  Knotts 
  

   and 
  Base 
  Brown, 
  and 
  down 
  the 
  valley 
  in 
  which 
  Comb 
  Gill 
  now 
  

   runs 
  due 
  north 
  from 
  Glaramara. 
  Just 
  above 
  Rosthwaite 
  it 
  was 
  

   joined 
  by 
  the 
  Stone 
  thwaite 
  glacier, 
  made 
  up 
  of 
  the 
  Longstrath 
  and 
  

   Greenup 
  ice-streams 
  (see 
  fig. 
  11). 
  The 
  union 
  of 
  these 
  two 
  glaciers 
  

   (Derwent 
  and 
  Stonethwaite) 
  formed 
  the 
  main 
  Borrowdale 
  glacier, 
  

   which 
  had 
  then 
  to 
  be 
  forced 
  through 
  the 
  narrowest 
  part 
  of 
  the 
  

   valley, 
  between 
  Rosthwaite 
  and 
  Grange, 
  a 
  great 
  ice-sheet 
  moving 
  

   over 
  the 
  fell-tops 
  on 
  the 
  east 
  side 
  more 
  or 
  less 
  coalescing 
  with 
  it 
  

   (see 
  Map, 
  PL 
  IX., 
  and 
  fig. 
  12). 
  

  

  The 
  old 
  Rosthwaite 
  Lake, 
  of 
  an 
  oval 
  form, 
  and 
  nearly 
  a 
  mile 
  in 
  

   length, 
  occurs, 
  it 
  should 
  be 
  noted, 
  just 
  beyond 
  the 
  junction 
  of 
  the 
  

   Derwent 
  and 
  Stonethwaite 
  glaciers, 
  and 
  where 
  the 
  ice, 
  after 
  having 
  

   its 
  rate 
  of 
  flow 
  somewhat 
  checked 
  at 
  the 
  junction, 
  would 
  have 
  acquired 
  

   an 
  additional 
  impetus 
  (see 
  Map, 
  PI. 
  IX.). 
  About 
  Grange 
  the 
  ice- 
  

   sheet 
  shed 
  off 
  Brund 
  Fell 
  and 
  down 
  the 
  "Watendlath 
  valley 
  joined 
  

   the 
  main 
  glacier 
  on 
  its 
  escaping 
  from 
  the 
  so-called 
  jaws 
  of 
  Borrow- 
  

   dale 
  (just 
  about 
  Castle 
  Crag, 
  fig. 
  12). 
  Thus 
  increased 
  in 
  mass, 
  the 
  

   ice 
  was 
  urged 
  through 
  the 
  valley, 
  over 
  the 
  present 
  site 
  of 
  Derwent- 
  

   water, 
  between 
  Cat 
  Bells* 
  and 
  Bleaberry 
  Fell 
  (fig. 
  13). 
  I 
  have 
  

   little 
  doubt 
  that 
  the 
  pressure 
  in 
  a 
  N.N.W. 
  direction 
  was 
  here 
  so 
  

   great 
  that 
  the 
  western 
  side 
  of 
  the 
  glacier 
  partly 
  escaped 
  over 
  the 
  

   Cat 
  Bell 
  ridge 
  — 
  especially 
  through 
  the 
  Hause 
  Gate, 
  between 
  Maiden 
  

   Moor 
  and 
  Cat 
  Bells 
  (fig. 
  3) 
  — 
  and 
  became 
  confluent 
  with 
  the 
  New- 
  

   lands 
  glacier 
  upon 
  the 
  other 
  side. 
  It 
  is 
  just 
  about 
  this 
  part 
  of 
  the 
  

   valley 
  (fig. 
  13) 
  that 
  the 
  greatest 
  depth 
  of 
  Derwentwater 
  is 
  found 
  — 
  

   a 
  depth, 
  however, 
  very 
  slight 
  as 
  compared 
  with 
  the 
  thickness 
  of 
  the 
  

   ice, 
  the 
  former 
  being 
  70 
  feet, 
  and 
  the 
  latter 
  something 
  like 
  1100. 
  

   Tracing 
  the 
  course 
  of 
  the 
  glacier 
  still 
  further 
  down 
  the 
  valley, 
  it 
  

   seems 
  that 
  about 
  Keswick 
  it 
  was 
  joined 
  by 
  several 
  other 
  large 
  ice- 
  

   sheets. 
  There 
  were 
  the 
  Xewlands 
  and 
  Coledale 
  glaciers 
  wedging 
  in 
  

   about 
  Braithwaite, 
  and 
  the 
  western 
  part, 
  at 
  any 
  rate, 
  of 
  the 
  great 
  ice- 
  

   sheet 
  coming 
  down 
  the 
  Thirlmere 
  valley, 
  pressing 
  along 
  the 
  Xaddle 
  

   * 
  Skelgill 
  Bank 
  in 
  fig. 
  13 
  is 
  the 
  northern 
  end 
  of 
  the 
  Cat 
  Bells 
  range. 
  

  

  