340 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Feb. 27, 



dmped of which there are vestiges in the bone-deposits is a Dog ; 

 whether an extinct or hving species is not determined. 



Summary. — From the facts described, it appears that in the Middle 

 Island of New Zealand, as in the North Island, the fundamental rocks 

 are metamorphic schists and clay-slate, with dikes of greenstone and 

 compact and amygdaloidal basalt, and intruded masses of obsidian, 

 vesicular and trachytic lavas, and other igneous products. Hornblende 

 and porphyritic rocks, gneiss and serpentine occur, but granite has 

 not been observed. 



The lofty mountain ranges of schistose metamorphic rocks that ex- 

 tend through the country, from near Cloudy Bay on the north-east 

 to near the south-western extremity of the island, a distance of be- 

 tween 300 and 400 miles, and whose crests everywhere attain an ele- 

 vation above the line of perpetual snow — hence they were called by 

 Captain Cook "The Southern Alps" — are flanked by volcanic grits, 

 and covered at their base by alluvial deposits, which have evidently 

 originated from the decay of trachytes and earthy lavas, and the detri- 

 tus of the harder materials which entered into their composition. No 

 active volcanos are known in the Middle Island, nor have any extinct 

 craters been discovered ; but as the physical structure of the interior 

 of the country, and especially of the Alpine districts, has been but par- 

 tially explored, no conclusive inferences can be drawn from this nega- 

 tive evidence. Strata of limestone, composed of organisms similar to 

 those which prevail in certain cretaceous beds of Europe, crop out in 

 a few localities on the eastern coast, from near Morakura to Kakaunui ; 

 but their relation to the adjacent igneous and metamorphic rocks has 

 not been ascertained. 



A pleistocene or newer tertiary formation — the clay of Onekakara 

 — abounding in shells of species existing in the neighbouring sea, 

 overlies the limestone, and is in many places covered by the alluvial 

 deposits of gravel, sand, conglomerate, and loam, which form the su- 

 perficial soil of the vast plains that are spread over the eastern side 

 of the central mountain chain. 



On the western shore of the North Island, argillaceous strata with 

 similar fossil shells appear at Wanganui, Waingongoro, &c. ; in both 

 islands these beds are from a few feet to 20 or 30 feet above the sea- 

 level. A subsidence of the land to the depth of 40 feet would unite 

 these outliers of a deposit, evidently once continuous ; we may there- 

 fore conclude that an elevation to that extent has taken place since 

 the deposition of the uppermost beds of the blue clay of Onekakara. 

 This phenomenon accords with the horizontal sediments containing 

 drift wood that occur along the coast, and with the terraces of bould- 

 ers of trap, 50 feet high, and the lines of ancient sea-margins now 

 far above the highest tides ; and these mutations in the relative level 

 of the sea and land must have taken place long since the Pacific was 

 inhabited by the existing species of mollusca. 



The infusorial earths show that deposits wholly composed of the 



