ry THE MEDALS OF CREATION. Cuap. VI. 
were observable. Beds of lignite occur in the neighbouring 
hills, both above and below the fossil trees ; many loca- 
lities along the eastern coast of Australia are mentioned, as 
presenting similar phenomena. I may add that the only 
fragment of petrified wood found by Mr. Walter Mantell in 
New Zealand is coniferous. 
In the valley of the Derwent, in Australia, opalized conife- 
vous trees of a similar character were observed under very 
extraordinary circumstances, by the distinguished traveller, 
Count Strzelecki. Truncated stems were found standing 
erect in a bed of scoriaceous basalt (lava) and trachytic con- 
glomerate : but in some instances only basaltic casts of the 
trunks remain. This curious phenomenon can only be ex- 
plained by supposing the silicified stems to have resisted the — 
intense heat of the incandescent lava, while trees placed in 
circumstances unfavourable to their petrifaction were con- 
sumed : but the latter, being either saturated with water, or 
fresh and green, were burnt slowly, and left cylindrical moulds 
in the cooled basaltic scoriee, with impressions of the external 
surface of the bark ; these moulds were filled up by a sub- 
sequent eruption, and thus basaltic casts of the consumed 
trees were formed.* 
ContFERous Woop IN Oxrorp CLay.—It would occupy too 
much space to notice the numerous localities in which fossil 
remains of conifers occur in the Liassic and Oolitic forma- 
tions of England. 
In the Oxford and Kimmeridge Clays waterworn trunks 
and branches of large pine-trees are often met with. An in- 
teresting deposit of these remains was brought to light by 
my youngest son (Mr. Reginald Mantell), when constructing 
the branch line of railway from the Great Western to Trow- 
bridge, in Wilts. In the progress of the work, extensive 
sections were cut through the Oxford Clay, and laid bare a 
large quantity of drifted wood, much of which was not 
* Physical Description of New South Wales, by Count Strzelecki. 
