STRZELECKl's N. S. WALES AND VAN DIEMEN'S LAND. 565 



It would seem that in those parts of Australia described by the 

 author there is no appearance of any rocks of the secondary 

 period, or even of the early or middle part of the tertiary period. 

 Of the newer tertiary, and perhaps almost the recent period we 

 find some interesting marks in the raised beaches disposed at 

 intervals along the present coast line, in the osseous breccia of the 

 caverns, and in the remarkable fossil trees spread over the surface 

 in some of the valleys, especially in Derwent valley (Van Die- 

 men's Land). The raised beaches contain shells of species still 

 common on the coast : the breccia have supplied Professor Owen 

 with the materials of a Report on the extinct mammalia of Aus- 

 tralia and a supplement to that Report, both published in the 

 volumes of the Proceedings of the British Association (1844, 1845), 

 and the remarkable opalized trees have been recently described 

 by Dr. Hooker, the naturalist in the expedition of H. M. S. 

 Erebus. 



The gravel of the valley of the Derwent is however hardly 

 less striking than these fossil trees. It consists of a multitude of 

 " boulders composed of cylindrical, somewhat flattened columns of 

 basalt confusedly heaped together with detritus of pebbles mixed 

 with spheroid boulders of greenstone rock, all lodged against an 

 escarpment situated at the bottom of the valley, and on the right 

 bank of the Derwent." (p. 148.) The escarpment is formed of 

 carboniferous rocks, and has been violently rent asunder probably 

 by volcanic disturbance of no very ancient date. 



Much still remains to be effected by careful and minute obser- 

 vation, and much also in the way of generalisation, before the 

 geological structure of the eastern portion of Australia can be 

 brought into relation with that of districts at present more mi- 

 nutely and clearly made out. Meanwhile, the gradual develop- 

 ment of facts bearing on the condition of the eastern and southern 

 continents during the secondary and early tertiary period can- 

 not fail to suggest hypotheses with regard to the condition of the 

 land in these parts of the world, the determination of which may 

 greatly influence the views of geologists concerning European and 

 American geology. 



D. T. A. 



VOL. I. QQ 



