6 W. N. BENSON 



which, however, the plant-bearing beds became relatively more 

 abundant in the South Island, and thin coal seams occur. Lower 

 (Liassic), Middle (Bajoccian), and Upper (Tithonian) Jurassic 

 marine faunas are recognized, and a sequence of small floras also, 

 but the detailed description of the first two has not yet appeared/ 

 There are also a series of sediments which are rather widespread 

 in the east of the North Island, and are perhaps of early Cretaceous 

 age, but may be in part Upper Jurassic. They contain Inoceramus 

 in some abundance. In the western side of the island, the Jurassic 

 rocks are followed conformably by early Cretaceous (Neocomian) 

 plant beds, containing two angiosperms. 



Orogeny. — -The orogenic movement which succeeded this long- 

 continued sedimentation reached its maximum in Lower Cretaceous 

 time. The Mesozoic sediments were forced into broken or overturned 

 folds, and zones of shattering were produced. The axis of such 

 folding is for the most part approximately meridional and generally 

 oblique to the much later warpings and fault-lines which determine 

 the northeasterly trend of the present mountain system. Plutonic 

 intrusions occurred in connection with this folding, among which 

 are a series of masses of ultrabasic and basic rocks appearing at 

 intervals from end to end of New Zealand. They are most note- 

 worthy near Nelson in the north of the South Island, where is the 

 type-locality of the rock dunite. The association of such intru- 

 sions with fault-zones is sometimes clear. In addition to these 

 are granites and syenites especially well developed in the northwest 

 of the South Island, but it is as yet problematical how much of the 

 more or less gneissic plutonic rocks of the southwestern region 

 should be referred to this series of intrusions. Among the minor 

 intrusions of this period are a restricted series of lamprophyric 

 dikes, monchiquites, etc. 



Undetermined schists. — We may here describe one of the most 

 puzzling formations in New Zealand, a broad zone of mica-schists 

 running to the southeast from the main mountain range, through 

 the Otago province of the South Island. These have for the 

 most part a very fiat position, but dip to the southwest and north- 



^ Trechmann and Spath have described this fauna since this paper was written. 

 See Quart. Journ. Geol. Soc, ig2i. 



