166 Transactions. — Geology. 



The sedimentary rocks are blue mud-stones, with greenish 

 or brown sandstones and occasional beds of conglomerate. 

 Granitic conglomerates are commonly found in Southland in 

 the "Upper, or Mataura, series ; and Mr. S. H. Cox says that he 

 has found them at the base of the Lower, or Wairoa, series, in 

 conjunction with beds of greenstone-ash and breccias, thus 

 showing that the granites are older than some of the basic 

 rocks. 



Eemains of plants are found all through the system, and in 

 the upper part thin seams of coal often occur. The most 

 characteristic plants are Pterophyllum, Podozamites , Thinn- 

 feldia, Tceniopteris, and Polypodiuvi. Fossil animals are 

 also tolerably abundant, and include Ammonites, Belcmnites, 

 Trigonia, Edmondia, Monotis, Trigonotreta, Spirifirina, and 

 Athyris. Also a single vertebral centrum, belonging pro- 

 bably to Ichthyosaurus, has been described by Sir James 

 Hector ; and teeth, apparently belonging to a Labyrintho- 

 dont, have been found near the Nuggets, in Otago, and 

 also in the Wairoa district, near Nelson. These fossils are 

 sufficient to prove that the rocks are of Lower Mesozoic 

 age, and probably they are the equivalents of the Trias-jura 

 formation of eastern Australia. 



Inferences from Vac Facts. 



We now come to a great break in the geological history of 

 New Zealand, and this enables me to pause in my narration of 

 facts and see what we have already learnt before going on to 

 the second part of the history. Our oldest rocks — those of 

 the Wanaka system — are undoubtedly the products of the 

 denudation of a land-surface, but where that land lay we can- 

 not tell. We are also quite as ignorant of what was taking 

 place in our part of the world during the older PaliEozoic era, 

 further than that the fossils of the Siluro-devonian rocks 

 seem to imply a shallower sea than that which prevailed in 

 the Ordovician period. 



The next fact we have is that, after the deposition of the 

 Siluro-devonian rocks, a synclinal trough was formed in nortli- 

 west Nelson and Westland, to the west of the present main 

 axis. Denudation followed, by means of which the Takaka 

 rocks were completely removed, except those preserved by the 

 syncline. This iu)plies the existence of a land-surface in our 

 area during the late Devonian or early Carboniferous. It is 

 possible that these movements took place in the middle of the 

 Devonian period in connection with similar ones which at that 

 time occurred in Australia ; and, if sucli is the case, land pro- 

 bably existed in the Upper Devonian in both the Australian 

 and New Zealand areas, so that thev mav have been con- 

 nected and formed part of a continent. But we have in New 



