BY W. G. WOOLNOUGH. 475 



artificial cutting shows a marked change in the character of the 

 rock. Tiie rock exposed is a fine slaty quartzite of undoubted 

 sedimentary origin. It is highly jointed; this phenomenon masks 

 an}^ very obvious contortions, so that in the short time available 

 for my observations I could not trace any line of folding. For 

 the same reason no detailed search for fossils could be made. 

 The rock is an anything but promising one for such a purpose. 



The joints are very regular for short distances, but do not con- 

 tinue to strike in the same directions in different outcrops. On 

 the whole there is, however, a marked tendency for certain of the 

 jointed planes to strike in a general north and south direction, 

 though with variable dip. 



These jointed quartzites continue to outcrop at intervals all the 

 way to the large town of Narokorokoyawa, a distance of more 

 than five miles. Many good sections are obtained as the track is 

 a made one, traversing the spurs of the hills instead of the river 

 bed as is usually the case. Narokorokoyawa stands on a very 

 extensive alluvial flat just below the junction of the main stream 

 with a large affluent coming from the east. The flat is about one 

 mile long. After crossing it a new type of rock is met with. 

 This is a moderately coarse-grained biotite granite, with very 

 abundant quartz and some hornblende. No perfectly fresh speci- 

 mens could be obtained, even in the road cuttings, but sufiiciently 

 undecomposed material for rock-section was procured. The petro- 

 logical details of this rock will be described in Part ii. of this 

 paper. Like all the other geologically old rocks met with, the 

 granite is much jointed, though not to the same extent as 

 the quartzites and quartz diorites described above. This rock 

 again forms a persistent outcrop and extends without interruption 

 for about 4i miles. Within the next mile and one-half several 

 alternations of granite and quartzite occur, but no junctions are 

 to be seen, as these points form lines of weakness and have, 

 therefore, given rise to valleys. The track crosses these valleys 

 too far below their heads to allow of the relations between granite 

 and quartzite being determined. 



