INTRODUCTION. 29 



In the second place, it has long been thought possible, especially by 

 Goppert 1 , that silicification was brought about by the ascent of the petri- 

 fying substance in the stems, which though dead were still standing erect 

 in the open air. Such erect petrified stems are mentioned by Hausmann a 

 still rooted in the beds of lignite at the Hirschberg near Gross-Almerode, 

 and according to Renault 3 are of not unfrequent occurrence in the depart- 

 ment of the Allier; similar objects were observed by Darwin 4 near 

 Uspallata on the Andes of South America as snow-white columns rising 

 above the ground, but they may, as Darwin supposes, have been laid bare 

 by denudation, and cannot therefore be applied in support of our con- 

 jecture. The stumps of trees rooted in the Nubian sandstone of Wadi 

 El Tih near Cairo and mentioned by Newbold and Unger 5 have never 

 been seen again, and are doubtful. The possibility of a genetic connection 

 between silicified fossil remains and geyser-springs, which cover everything 

 round them with siliceous sinter, I find to have been first suggested by 

 Schimper in the Introduction to his ' Trait6 de Paleontologie.' 



O. Kuntze 6 , impressed by the facts which he observed in the geyser 

 district of the National Park Territory in North America and which will be 

 discussed presently, has since adopted the above idea and combined it with 

 Goppert's view ; but he has at the same time extended it in a manner 

 which is certainly inadmissible, since he would account for all silicified 

 wood in this way. He depicts the state of things which he found at the 

 Boiling Lake geyser in the following words : ' I saw the wood in the 

 immediate vicinity of the geyser destroyed, and that in a very peculiar 

 manner ; where the hot water from the geyser had run among the trees, 

 they had lost their leaves, rind, and many of their branches, and had 

 assumed a white colour, and in some cases their outer substance had 

 become soft (see the remarks on this point on p. 21) ; most of the trees 

 were still standing, but many had fallen, and of these some were entirely 

 rotted inside, whilst others, like those still standing, were in exactly the 

 same condition as the pieces of wood which had been thrown by visitors 

 from time to time into the basin of the geyser, that is, they were im- 

 pregnated with the silicate from the siliceous water and were become white 

 and soft. But there was one distinction to be observed, that the silicic 

 acid in the wood which lay in the water had not become hard but had 

 remained soft, while in the trees in the open air the hardening of the 

 wood containing the silica was advancing gradually from without inwards ; 

 some trees were still soft and still showed the woody fibres, others were 

 harder and the decayed woody fibre was replaced by a deposit of silica 

 of similar structure.' Further on he draws conclusions from these cir- 



1 Goppert (1), Introd. 2 Hausmann (2), p. 150. 3 Renault (2), i, Introd. * Darwin, 



Voyage, ii ? p. 99. 5 Unger (7). 6 Kuntze (1). 



