﻿94 
  A. 
  C. 
  RAMSAY 
  ON 
  THE 
  PHYSICAL 
  HISTORY 
  

  

  Discussion. 
  

  

  Mr. 
  Campbell, 
  in 
  illustration 
  of 
  the 
  paper, 
  and 
  of 
  the 
  effects 
  

   which 
  running 
  water 
  is 
  capable 
  of 
  producing, 
  brought 
  forward 
  some 
  

   views 
  in 
  Daghestan 
  and 
  the 
  Caucasus. 
  Yery 
  considerable 
  tracts 
  of 
  

   this 
  country 
  are 
  drained 
  by 
  canons, 
  very 
  narrow, 
  but 
  some 
  hundreds 
  

   of 
  feet 
  in 
  depth 
  ; 
  the 
  streams 
  which 
  pass 
  along 
  them 
  are 
  principally 
  

   fed 
  by 
  melting 
  snow. 
  

  

  Prof. 
  Hughes 
  doubted 
  the 
  view 
  which 
  referred 
  the 
  present 
  Rhine 
  

   to 
  any 
  configuration 
  of 
  the 
  country 
  due 
  to 
  the 
  original 
  level 
  surface 
  

   of 
  the 
  Miocene 
  while 
  it 
  ignored 
  the 
  post-Miocene 
  elevation 
  of 
  the 
  

   Alps 
  and 
  Jura. 
  He 
  had 
  traced 
  the 
  lava 
  from 
  the 
  Forniche 
  Kopf, 
  

   near 
  Andernach, 
  down 
  to 
  within 
  100 
  feet 
  of 
  the 
  present 
  Rhine. 
  He 
  

   thought, 
  therefore, 
  that 
  the 
  Rhine 
  began 
  to 
  cut 
  back 
  a 
  channel 
  by 
  

   rapids 
  and 
  waterfalls, 
  from 
  the 
  Rolandseck 
  end, 
  at 
  the 
  first 
  appear- 
  

   ance 
  of 
  the 
  land 
  above 
  the 
  Miocene 
  sea, 
  and 
  before 
  the 
  close 
  of 
  the 
  

   earth-movements 
  aud 
  volcanic 
  eruptions 
  which 
  seem 
  to 
  be 
  con- 
  

   nected 
  with 
  the 
  later 
  Miocene, 
  but 
  that 
  it 
  took 
  the 
  river 
  so 
  long 
  to 
  

   eat 
  its 
  way 
  back 
  as 
  far 
  as 
  Bingen 
  that 
  it 
  had 
  time 
  to 
  wind 
  about 
  

   and 
  form 
  a 
  broad 
  valley 
  in 
  the 
  upper 
  part 
  of 
  its 
  course 
  — 
  that 
  the 
  

   river 
  continued 
  to 
  run 
  at 
  the 
  higher 
  level 
  at 
  the 
  Bingen 
  end 
  until, 
  

   at 
  a 
  comparatively 
  far 
  less 
  remote 
  period, 
  the 
  gorge 
  was 
  eaten 
  back 
  

   through 
  this 
  fiat 
  valley 
  ; 
  and 
  when 
  once 
  the 
  river 
  had 
  got 
  through 
  

   the 
  harder 
  rocks 
  near 
  Bingen, 
  it 
  soon 
  disposed 
  of 
  the 
  softer 
  beds 
  in 
  

   the 
  Mayence 
  basin. 
  

  

  Mr. 
  Koch 
  was 
  inclined 
  to 
  think 
  that 
  the 
  Jura 
  chain 
  had 
  existence 
  

   in 
  Miocene 
  times, 
  as 
  beds 
  of 
  that 
  age 
  lay 
  horizontally 
  in 
  hollows 
  in 
  

   the 
  Jurassic 
  rocks. 
  He 
  quite 
  agreed 
  with 
  Prof. 
  Ramsay 
  as 
  to 
  the 
  

   terraces 
  along 
  the 
  sides 
  of 
  the 
  Rhine 
  gorge. 
  

  

  Mr. 
  Tiddeman 
  did 
  not 
  see 
  the 
  difficulties 
  suggested 
  by 
  Prof. 
  

   Hughes. 
  

  

  The 
  Duke 
  of 
  Argyll 
  remarked 
  that 
  if 
  the 
  physical 
  history 
  of 
  the 
  

   Rhine 
  were 
  established, 
  it 
  would 
  throw 
  much 
  light 
  on 
  that 
  of 
  other 
  

   great 
  rivers. 
  He 
  considered 
  the 
  paper 
  of 
  great 
  value, 
  but 
  suggested 
  

   a 
  doubt 
  whether 
  the 
  history 
  assigned 
  would 
  account 
  for 
  all 
  the 
  phe- 
  

   nomena 
  exhibited 
  along 
  the 
  course 
  of 
  the 
  river. 
  There 
  appeared 
  to 
  

   have 
  been 
  at 
  the 
  commencement 
  of 
  the 
  existence 
  of 
  the 
  river 
  several 
  

   upheavals 
  of 
  the 
  land, 
  but 
  subsequent 
  to 
  the 
  main 
  upheaval 
  of 
  the 
  

   Alps. 
  He 
  regarded 
  the 
  channel 
  of 
  the 
  river 
  as 
  entirely 
  due 
  to 
  flu- 
  

   viatile 
  action, 
  but 
  he 
  confessed 
  to 
  having 
  some 
  doubt 
  whether 
  the 
  

   erosion 
  of 
  the 
  river 
  alone 
  could 
  have 
  effected 
  the 
  enormous 
  amount 
  

   of 
  denudation 
  exhibited 
  in 
  the 
  district. 
  He 
  inquired 
  whether 
  there 
  

   was 
  not 
  a 
  possibility 
  of 
  some 
  marine 
  denuding 
  power 
  also 
  having 
  

   been 
  at 
  work. 
  He 
  also 
  inquired 
  as 
  to 
  the 
  flexure 
  of 
  the 
  rocks 
  and 
  

   subterranean 
  movements 
  affecting 
  the 
  conditions 
  of 
  the 
  case, 
  espe- 
  

   cially 
  in 
  connexion 
  with 
  the 
  angles 
  at 
  which 
  the 
  Miocene 
  strata 
  are 
  

   tilted. 
  A 
  third 
  question 
  alluded 
  to 
  by 
  Prof. 
  Hughes 
  was 
  as 
  to 
  the 
  

   volcanic 
  action 
  that 
  had 
  gone 
  on 
  in 
  the 
  valley 
  of 
  the 
  Rhine 
  ; 
  and 
  he 
  

   wished 
  to 
  know 
  whether 
  that 
  might 
  not 
  also 
  have 
  conduced 
  towards 
  

   the 
  present 
  contour 
  of 
  the 
  valley. 
  As 
  to 
  the 
  terraces, 
  he 
  accepted 
  

  

  