﻿2 
  PROFESSOR 
  FORBES 
  ON 
  THE 
  VOLCANIC 
  GEOLOGY 
  OF 
  THE 
  VIVARAIS. 
  

  

  usual 
  thoroughfare 
  of 
  the 
  Rhone, 
  down 
  which 
  travellers 
  and 
  tourists 
  glide 
  by 
  

   thousands, 
  without 
  spending 
  a 
  thought 
  upon 
  the 
  intricate 
  country 
  which 
  lies 
  on 
  

   their 
  right, 
  their 
  attention 
  being 
  rather 
  attracted 
  to 
  the 
  more 
  striking 
  features 
  of 
  

   the 
  outlying 
  portions 
  of 
  the 
  Alpine 
  chain 
  on 
  the 
  left, 
  where 
  the 
  noble 
  outlines 
  of 
  

   the 
  mountains 
  of 
  Dauphine 
  hold 
  out 
  a 
  more 
  tempting 
  prospect 
  of 
  romantic 
  

   scenery 
  and 
  of 
  geological 
  interest. 
  

  

  Nevertheless, 
  from 
  a 
  very 
  early 
  period 
  of 
  the 
  revival 
  of 
  geological 
  studies 
  in 
  

   these 
  latter 
  times, 
  the 
  Provinces 
  of 
  the 
  Ardeche 
  and 
  Haute 
  Loire 
  (the 
  ancient 
  

   Vivarais 
  and 
  Velay) 
  attracted 
  considerable 
  notice. 
  When 
  men 
  were 
  no 
  longer 
  

   content 
  to 
  ascribe, 
  with 
  Voltaire, 
  the 
  presence 
  of 
  extraneous 
  fossils 
  in 
  mountain 
  

   rocks 
  to 
  the 
  passage 
  of 
  pilgrims 
  with 
  their 
  scallop 
  shells, 
  — 
  or 
  with 
  others, 
  the 
  

   scoriae 
  of 
  ancient 
  volcanoes, 
  covering 
  an 
  area 
  of 
  many 
  square 
  miles, 
  to 
  the 
  iron 
  

   forges 
  of 
  the 
  Romans, 
  — 
  they 
  began, 
  very 
  properly, 
  to 
  compare 
  the 
  marks 
  of 
  the 
  

   most 
  apparently 
  recent 
  changes 
  of 
  the 
  earth's 
  surface, 
  not 
  however 
  belonging 
  to 
  

   the 
  historic 
  period, 
  with 
  those 
  going 
  on 
  under 
  our 
  own 
  eyes, 
  such 
  as 
  the 
  eruptions 
  

   of 
  volcanoes, 
  and 
  by 
  clearly 
  establishing 
  identity 
  of 
  effects 
  in 
  some 
  cases, 
  were 
  led 
  

   to 
  almost 
  irresistible 
  conclusions 
  from 
  analogy 
  in 
  others. 
  Thus 
  the 
  presence 
  of 
  

   volcanic 
  craters, 
  scoriae, 
  and 
  lava 
  currents, 
  in 
  several 
  parts 
  of 
  central 
  France, 
  

   could 
  not 
  be 
  doubted 
  by 
  any 
  one 
  who 
  had 
  seen 
  the 
  burnt 
  ground 
  of 
  Etna 
  or 
  

   Vesuvius. 
  The 
  phenomena 
  should 
  rather 
  be 
  called 
  identical 
  than 
  analogous 
  ; 
  

   but 
  the 
  argument 
  of 
  analogy 
  from 
  the 
  lavas 
  thus 
  detected, 
  to 
  the 
  volcanic 
  origin 
  

   of 
  lava-like 
  stone 
  or 
  basalt 
  in 
  many 
  countries 
  where 
  no 
  red 
  scoria?, 
  no 
  declivitous 
  

   streams 
  of 
  once 
  melted 
  matter, 
  and 
  no 
  indubitable 
  craters 
  could 
  be 
  found, 
  opened 
  

   up 
  a 
  field 
  for 
  more 
  prolonged 
  study, 
  and 
  more 
  cautious 
  generalization. 
  In 
  this 
  

   department 
  Faujas 
  de 
  St 
  Fond, 
  a 
  native 
  of 
  the 
  Vivarais, 
  distinguished 
  himself 
  ; 
  

   and 
  with 
  great 
  industry, 
  and 
  considerable, 
  though 
  not 
  invariable 
  judgment, 
  he 
  

   set 
  about 
  identifying 
  the 
  features 
  of 
  the 
  unquestionable 
  lava 
  streams 
  of 
  his 
  own 
  

   country 
  with 
  more 
  obscure, 
  because 
  more 
  ancient 
  ejections 
  of 
  melted 
  matter 
  

   forming 
  rocks 
  on 
  the 
  surface, 
  not 
  only 
  there, 
  but 
  in 
  distant 
  countries, 
  particularly 
  

   in 
  Great 
  Britain, 
  whither 
  he 
  made 
  a 
  journey 
  on 
  purpose. 
  To 
  establish 
  indubitably 
  

   the 
  connection 
  of 
  basalts 
  with 
  lavas 
  was 
  the 
  main 
  object 
  of 
  his 
  large 
  work 
  

   in 
  folio, 
  on 
  the 
  Extinct 
  Volcanoes 
  of 
  the 
  Vivarais 
  and 
  Velay, 
  published 
  in 
  1778,* 
  

   which 
  contains 
  observations 
  of 
  merit, 
  and 
  descriptions 
  generally 
  exact, 
  notwith- 
  

   standing 
  the 
  rudeness 
  of 
  the 
  engravings 
  by 
  which 
  they 
  are 
  illustrated. 
  This 
  work 
  

   contains, 
  perhaps, 
  the 
  most 
  complete 
  description 
  of 
  the 
  volcanic 
  district 
  of 
  the 
  

   department 
  of 
  the 
  Ardeche 
  which 
  has 
  yet 
  been 
  published, 
  and 
  the 
  ample 
  nar- 
  

   rative 
  of 
  Faujas 
  has 
  been 
  the 
  guide 
  of 
  every 
  subsequent 
  explorer 
  (and 
  they 
  have 
  

   not 
  been 
  numerous) 
  of 
  this 
  remarkable 
  country. 
  The 
  circumstance 
  of 
  proximity 
  

   of 
  situation, 
  which 
  led 
  Faujas 
  to 
  explore 
  the 
  hills 
  of 
  his 
  own 
  neighbourhood 
  (for 
  

  

  * 
  Recherches 
  sur 
  les 
  Volcans 
  eteints 
  du 
  Vivarais 
  et 
  du 
  Velay, 
  avec 
  un 
  discours 
  sur 
  les 
  vol 
  cans 
  

   brulans, 
  &c. 
  Grenoble 
  et 
  Paris, 
  1778. 
  

  

  