Page:A Voyage of Discovery and Research in the Southern and Antarctic Regions Vol 2.djvu/24

10 was burst asunder is obvious, as is also the action of the water upon it. The position of the detritus, and the direction of the axes of the columns, which lie in position corresponding to the present fall of the country, that is, at the lowest level of the valley, prove that the disturbing forces acted from within the basin.

"This is corroborated further by the evidences of the basaltic and trachytic irruption which occurred after the deposition of the variegated sandstones in Van Diemen's Land. That irruption seems to have appeared first about Rose Garland, which is the centre of the valley. The trees there, which had been fossilized, withstood the intensity of the incandescent matter: other trees, placed in circumstances less favourable to their previous fossilization, were consumed; but being either saturated with water, or still green, they resisted in some measure the process of combustion, and have left behind longitudinal moulds in the basaltic scoriæ, with parietal cavities or impressions, similar to the rugged appearance which the carbonization of a tree assumes externally. Into some of these moulds, a second irruptive force appears to have injected fresh lava, thus forming casts of the consumed trees, and records of the succession of volcanic agencies.

"This irruption was followed by that of greenstone in the upper part of the valley; which, accompanied as it was by a sudden upward movement of the bottom, must have precipitated the waters