12 W. N. BENSON 



become a classical district for the study of later Tertiary marine 

 rocks in the Southern Hemisphere. A nearly continuous line of 

 sea chffs exposes a thickness of 3,500 feet of gently dipping clay 

 stones. No break is seen in the succession, nor any sign of faulting, 

 though two carbonaceous layers indicate temporary land-surfaces. 

 Large collections of shells were made by Marshall and Murdoch 

 at four different horizons. In the lowest were 61 per cent of 

 Recent forms; in the next 76 per cent; in the next 90 per cent; 

 and in the highest 93 per cent. Sands containing only modern 

 shells rest with obvious unconformity upon this series, an almost 

 dramatic conclusion to the Tertiary record. 



Middle Tertiary faunas. ^The marine faunas of Middle Tertiary 

 times in New Zealand contain many new immigrant forms and 

 show signs of South American influence, which scarcely are sufflcient 

 to indicate coastal connection at this time, though the affinity of 

 the New Zealand fauna with that of South America is greater than 

 that with Austraha. Moreover, since the Middle Tertiary period 

 New Zealand appears to have been entirely isolated.^ The modern 

 marine fauna is but a diminished residue of the Middle Tertiary 

 fauna, and its specific and generic distinctness from Australian 

 forms precludes a connection of these areas in "Pliocene" and 

 post-" Pliocene " time. 



Vulcanism. — During the Notocene period there was considerable 

 volcanic activity. Its earhest manifestation was in a few Middle 

 Cretaceous basaltic eruptions in the northeastern portion of the 

 South Island, and rhyolitic extrusions, to the east and west of 

 Christchurch, which are probably Upper Cretaceous. There are 

 also west of Christchurch some post- Jurassic, pre-Senonian ande- 

 sites, the relations of which are now being investigated. The 

 products of early and middle Tertiary activity are much more 

 important and widespread. Economically the most important 

 among these were the andesites and dacites^ of the Coromandel 

 Peninsula, North Island, in which post-magmatic solutions have 

 developed great auriferous deposits. Rhyohtes also occur in this 



1 It is of interest to note in this connection that characteristic genera of modern 

 New Zealand plants are represented among the Tertiary fossil leaves in Grahams Land. 



2 Included with the basic volcanic rocks in map herewith. 



