﻿82 
  A. 
  C. 
  RAMSAY 
  ON 
  THE 
  PHYSICAL 
  HISTORY 
  

  

  Rolandseck, 
  through 
  which 
  the 
  waters 
  of 
  the 
  Rhine 
  escape 
  into 
  the 
  

   lower 
  plain 
  ? 
  

  

  Looking 
  south 
  from 
  the 
  hills 
  above 
  Bingen, 
  or 
  from 
  the 
  northern 
  

   slopes 
  of 
  the 
  Taunus, 
  the 
  impression 
  readily 
  rises 
  in 
  the 
  mind 
  that 
  

   the 
  vast 
  plain, 
  hounded 
  on 
  all 
  sides 
  by 
  hills, 
  must 
  have 
  been 
  a 
  lake 
  

   at 
  a 
  very 
  recent 
  geological 
  period, 
  and 
  that 
  the 
  opening 
  of 
  the 
  gorge 
  

   was 
  the 
  cause 
  of 
  the 
  drainage 
  of 
  this 
  supposed 
  body 
  of 
  water 
  170 
  

   miles 
  in 
  length. 
  Several 
  observers 
  have 
  entertained 
  this 
  idea, 
  at 
  

   least 
  in 
  conversation 
  with 
  me; 
  and 
  this 
  popular 
  notion 
  may 
  be 
  

   found 
  printed 
  in 
  Baedeker's 
  Guide-book. 
  The 
  opening 
  of 
  the 
  gorge 
  

   was 
  formerly 
  sometimes 
  attributed 
  to 
  the 
  disturbance 
  and 
  wide 
  frac- 
  

   ture 
  of 
  the 
  Devonian 
  strata 
  through 
  which 
  the 
  river 
  runs, 
  though 
  it 
  

   is 
  unlikely 
  that 
  this 
  view 
  is 
  now 
  at 
  all 
  generally 
  held. 
  

  

  For 
  many 
  years 
  I 
  also 
  inclined 
  to 
  the 
  hypothesis 
  that 
  the 
  long 
  

   plain 
  above 
  the 
  gorge 
  might 
  have 
  been 
  a 
  lake 
  in 
  geological 
  times 
  

   comparatively 
  recent. 
  I 
  also 
  thought 
  it 
  not 
  unlikely 
  that 
  the 
  action 
  

   of 
  glaciers 
  might 
  at 
  least 
  have 
  assisted 
  in 
  the 
  work 
  of 
  excavating 
  

   the 
  hollow, 
  bordered 
  as 
  it 
  is 
  on 
  three 
  sides 
  by 
  well-known 
  old 
  

   glacier-regions 
  — 
  Switzerland 
  on 
  the 
  south, 
  the 
  Schwarzwald 
  on 
  the 
  

   east, 
  and 
  the 
  Vosges 
  on 
  the 
  west 
  ; 
  and 
  this 
  year 
  I 
  determined 
  to 
  put 
  

   the 
  whole 
  question 
  to 
  the 
  proof. 
  

  

  As 
  I 
  proceeded 
  with 
  the 
  work, 
  I 
  could 
  find 
  no 
  signs 
  of 
  moraine 
  

   matter 
  on 
  the 
  slopes 
  near 
  Bingen 
  and 
  Mainz, 
  no 
  evidence 
  that 
  

   the 
  glaciers 
  of 
  the 
  Schwarzwald 
  and 
  the 
  Yosges 
  had 
  ever 
  been 
  

   large 
  enough 
  to 
  descend 
  into 
  the 
  plains 
  of 
  the 
  Rhine, 
  or 
  that 
  the 
  

   great 
  old 
  glaciers 
  of 
  Switzerland 
  had 
  ever 
  reached 
  the 
  Rhine 
  valley 
  

   as 
  far 
  as 
  Basel 
  ; 
  and 
  therefore 
  glaciers 
  seem 
  to 
  have 
  had 
  nothing 
  to 
  

   do 
  with 
  the 
  excavation 
  of 
  the 
  hollow. 
  Point 
  by 
  point, 
  all 
  the 
  other 
  

   circumstances 
  that 
  might 
  have 
  helped 
  to 
  support 
  a 
  post-Miocene 
  

   lake-theory 
  also 
  gave 
  way 
  ; 
  and 
  beginning 
  anew 
  with 
  fresher 
  and 
  

   sounder 
  data, 
  founded 
  on 
  more 
  accurate 
  knowledge 
  of 
  the 
  physical 
  

   geography 
  and 
  geology 
  of 
  the 
  area 
  than 
  I 
  previously 
  possessed, 
  I 
  at 
  

   length 
  arrived 
  at 
  certain 
  definite 
  conclusions. 
  

  

  In 
  connexion 
  with 
  the 
  subject, 
  it 
  is 
  of 
  importance 
  to 
  endeavour 
  to 
  

   ascertain 
  approximately 
  the 
  geological 
  date 
  at 
  which 
  the 
  waters 
  of 
  the 
  

   Rhine 
  began 
  to 
  flow 
  in 
  their 
  present 
  course 
  ; 
  and 
  to 
  do 
  this 
  it 
  is 
  neces- 
  

   sary 
  to 
  state 
  briefly 
  some 
  of 
  the 
  later 
  events 
  relating 
  to 
  the 
  history 
  of 
  

   the 
  Alps, 
  and 
  of 
  the 
  Miocene 
  strata 
  of 
  Switzerland 
  and 
  the 
  Rhine. 
  

  

  It 
  is 
  well 
  known 
  that 
  the 
  Alps, 
  as 
  a 
  mountain-range, 
  existed 
  in 
  

   some 
  form 
  before 
  and 
  during 
  the 
  deposition 
  of 
  the 
  Miocene 
  strata 
  

   (see 
  Map, 
  fig. 
  2) 
  ; 
  and 
  considering 
  the 
  length 
  of 
  time 
  that 
  has 
  elapsed 
  

   since 
  the 
  beginning 
  of 
  that 
  epoch 
  in 
  those 
  regions, 
  and 
  the 
  amount 
  

   of 
  waste 
  that 
  all 
  the 
  preexisting 
  Alpine 
  rocks 
  have 
  undergone 
  

   during 
  and 
  since 
  that 
  period, 
  it 
  may 
  perhaps 
  be 
  assumed, 
  notwith- 
  

   standing 
  the 
  subsequent 
  elevation 
  that 
  attended 
  the 
  disturbance 
  of 
  

   the 
  Miocene 
  rocks, 
  that 
  relatively 
  to 
  the 
  Miocene 
  deposits 
  the 
  Alps 
  

   may 
  have 
  been 
  during 
  Miocene 
  times 
  as 
  high 
  above 
  the 
  level 
  of 
  the 
  

   sea 
  as 
  they 
  are 
  now. 
  

  

  One 
  of 
  the 
  most 
  striking 
  proofs 
  of 
  the 
  waste 
  of 
  these 
  older 
  Alps 
  

   during 
  Miocene 
  times 
  is 
  found 
  in 
  the 
  well-known 
  conglomerates 
  or 
  

  

  