J. A. Thomson. — Igneous Intrusions of Mount Tapuaemika. 309 



Innumerable dykes, forming a perfect network, traverse the older rocks 

 in the upper part of the watersheds of the Branch, Dart, and Muzzle Rivers, 

 Clarence Valley, and trend north to the top of the Inward Kaikoura Range 

 into the watersheds of the Dee and Mead Rivers. The rocks are described 

 as green porphyritic rock, light-grey elvau rock, hornblende rock, fine- 

 grained basaltic rock, &c. It is, doubtless, from these dykes that the 

 specimens studied were derived. There is a great development of similar 



Scale of Miles 



Locality Map. 



dykes on the Awatere side of the range. McKay considers that these dykes 

 belong to a series older than those intersecting the Cretaceous rocks, since 

 the basal Cretaceous conglomerates contain pebbles of similar character. 

 The pre-('retaceous dykes he again divides into two series, relying on the 

 fact that the darker and denser dykes usually intersect the lighter syenitic 

 intrusions. 



The rocks described in this paper consist apparently of the pre-Cretaceous 

 series of McKay. There is such an air de famille about the whole collection 

 as to suggest that they all belong to one series of intrusions. Naturally. 



