36 The Origin of the 



dant in all the granitic and porphyritic formations of 

 the world. Large trunks of trees, and timber in 

 old mines which have been long under water, have 

 been found silicified in a comparatively short period. 

 Even vegetation contains a proportion of silica taken 

 up by the roots, and crystals have been found in the 

 cells, and often large ones in the bamboo. There 

 are (he adds) immense siliceous and calcareous 

 stumps, in their natural growing position, in Chili, 

 Veraguas, in Australia and Egypt ; showing most 

 distinctly that the trees were silicified when in the 

 act of growing, by an excess of silica and lime 

 getting into the soil. The upper part having 

 decayed, the whole forests appear to have been 

 snapped off by the winds nearly at the same time, 

 the brittle character of the stumps having caused 

 them to break off like glass horizontally a few feet 

 in height.' ' What my reader may think of the 

 credibility of this theory of the entire silicification of 

 the trunks of trees while actually growing, I know 

 not. To what extent it maybe possible for siliceous 

 infiltration to go on, being drawn up with the sap 

 during the life of the tree, may admit of inquiry or 

 perhaps even experiment; but it seems to me 

 improbable that it could proceed in living trees to 

 the total silicification of the trunk, as is implied in 

 the general theory thus propounded by Mr. Hopkins. 

 Perhaps a process begun to a moderate extent during 

 vegetable life, might be continued and completed by 

 attraction of affinity afterwards when the tree was 

 dead. It is not for me to conjecture. 



In our own Isle of Portland there is a remarkable 

 stratum of soil to be seen in the quarries, containing 

 stems of prostrate silicified trees, and also petrified 

 tree-stumps erect and rooted in the soil. I have 



