38 The Origin of the 



the ravines communicating with the Dneister, near 

 Moghilef, we are informed that there is found 

 siliceous wood in considerable quantity, which much 

 resembles that of Portland ; and also that siliceous 

 wood resembling that of the palm-tree has been 

 found near Tomaspool. 8 These cases, it will be seen, 

 are not analogous to the specimens from the flint 

 and chalk formation, nor even to those of Cairo. 



I have also received some siliceous specimens 

 from Colorado and Montana through the kindness 

 of friends ; in one of which, from the petrified 

 Forest of Colorado, 9 the converted wood-fibre is 

 perfect throughout even to the minutest microscopic 

 filament. The Colorado springs are strongly im- 

 pregnated with soda, which contributes to the 

 aqueous solution of silex, and there are also hot 

 springs. In some other cases the specimens present 

 only the cast of the bark, or of the fragment of 

 wood, with an interior of stone destitute of fibre. 



8 The Hon. Mr. Strangways on the Geology of Kussia (1821). 

 Trans, of Geol. Soc, vol. i. p. 39, note. 



9 The following extract gives some interesting particulars : — 

 "A Petrified Forest. — The petrified forest near Corizo, on the Little 

 Colorado, is a sight which travellers should not miss. The visitor 

 to the forest begins to see the signs of petrifaction hours before he 

 reaches the wonder. Here and there, at almost every step in the 

 road, small pieces of detached limbs and larger stumps of trees may 

 be seen almost hidden in the white sand. The road at a distance of 

 ten miles from Corizo enters an immense basin, the slope being 

 nearly a semicircle, and this is enclosed by the high banks of shale 

 and white clay. The petrified stumps, limbs, and, in fact, whole 

 trees, lie about on all sides ; the action of the waters for hundreds 

 of years has gradually washed away the high hills round about, 

 and the trees that once covered the high table-lands now he in the 

 valley beneath. Immense trunks, some of which measure over 

 five feet in diameter, are broken and scattered over a surface of 

 300 acres." — Iron. 



