Park. — On the Jurassic Age of the Mailai Series. 443 



region the granite and a great variety of related crystalline 

 rocks are associated with Silurian slates, schists, quartzite, 

 and limestone, which are in places richly fossiliferous. 



We must therefore conclude that an extension of the 

 Mount Arthur system, with its associated granites, formed the 

 old littoral of the Nelson basm, and now forms the floor of the 

 Waimea Plain, Moutere gravel hills, and Motueka Valley. 



The open Triassic sea extended southward into Marl- 

 borough, and in that direction the pelagic sediments would 

 be finer and organic remains rarer than along the shores of 

 the Nelson basin. 



General Conclusions. 



Summarising the results recorded in the preceding pages, 

 we find (a) that the Trias rocks everywhere dip below the 

 Maitai formation ; (6) that the Maitai formation is principally 

 characterized by the presence of the Secondary genus Inocera- 

 vins ; and (c) that the Trias contains such characteristic 

 Lower Mesozoic forms as Halohia lommeli and Monotis sali- 

 naria. 



The stratigraphical evidence alone seems amply conclusive 

 of the subsequent date of the Maitais ; but, setting this aside, 

 it seems impossible for any student of geology to seriously 

 maintain a Carboniferous age for a formation characterized by 

 such a truly Mesozoic genus as Inoceramus. 



The Maitai formation, although typically developed in the 

 neighbourhood of Nelson, is one of the most important rock- 

 formations in New Zealand — its importance lying in the fact 

 that it is one of our principal mountain-builders. 



Having shown it to be of subsequent date to the Trias 

 has a wider significance than its local relationships might in- 

 dicate. The Maitai formation possesses the closest strati- 

 graphical connection with the Trias not only in Nelson, but 

 throughout New Zealand. Where one is present the other is 

 seldom, perhaps never, absent. The two formations form one 

 great stratigraphical system, and are so closely associated 

 in the structural features of the country that a definition of 

 the geographical limits of the one must always include that of 

 the other. 



Eocks belonging to the Jurassic system, in association 

 with those of the Trias, form the greater portion of the Tara- 

 rua, Euahine, and Kaimanawa Mountains in the North 

 Island ; while outlying patches occur in the Upper Mokau, at 

 Kawhia, Eaglan, Waikato Heads, Kaipara, and Eodney dis- 

 tricts, in the Province of Auckland. And we have no reason 

 to assume a greater age for the slaty shales, sandstones, and 

 greywackes which form the floor of the Hauraki Peninsula. 



In the South Island this great Juro-triassic or Juro- 



