262 Transaction*. 



increasing distance from the open sea. Before the delta of the Hutt River, 

 at the head of Port Nicholson, is reached, effects of wave-action have shrunk 

 to small dimensions, and the spurs which run down into the flats of the delta 

 are not truncated at all. 



It will be gathered from the above description and from fig. 11 that 

 the eastern shore of the harbour presents characters similar to those of any 

 ridge in highly inclined stratified rocks, determined by the resistant nature 

 of the stratum of which it forms the outcrop. It is continuous with the 

 ridge forming the divide east of the Hutt River. This divide runs for some 

 distance parallel with and very close to the Hutt River ; hence the tribu- 

 taries entering the Hutt, or its continuation, Port Nicholson, can be only short, 

 steep-grade torrents. The nearness of the divide to the Hutt at this point 

 is explained by the fact that the ridge is composed of the strong greywacke 

 with few joints, which is the hardest rock in the district. If, on the other 

 hand, the ridge-face were determined by a line of recent faulting, and the 

 ridge itself were composed of rocks of average or varying hardness, it might 

 be expected that some of the streams of the fault-scarp would have worked 

 through and captured the drainage at the back, as the streams of the Wel- 

 lington fault-scarp have done. This ought all the more to be expected in the 

 case under discussion, since, if it be a case of faulting, the actual scarp has 

 reached a much more mature stage of dissection than the scarp of the 

 Wellington fault. 



The question of what actually is the eastern boundary of the Port 

 Nicholson depression must for the present remain open. 



There remains the line on the western side from Kelburne through the 

 City of Wellington to the sea on the south. This is the line of one of McKay's 

 faults (No. 3).* A section across this fault or a branch of it may be seen in 

 the cuttings of the Brooklyn tramway, but the section gives no information 

 as to the date of faulting or amount of movement. There is rather indefinite 

 evidence of faulting in the steep scarp along the front of Kelburne and 

 Brooklyn (the line AB in fig. 2). Evidence of faulting is much obscured 

 owing to the fact that the line of fracture appears to have followed the 

 course of a longitudinal mature valley in weak rock, the floor of which was 

 very deeply weathered. The amount of movement appears to have been 

 between 200 ft. and 300 ft. Farther south there is little evidence of a scarp, 

 and the fault was perhaps replaced by a flexure. 



Changes in Drainage of the Karori-Khandallah or Long Valley. 



This old valley might be called the Karori-Khandallah Valley, from the 

 names of two important settlements in it. For the sake of brevity, it is here 

 called the " Long Valley." Its line is now followed by the Silver Stream, the 

 Kaiwarra and its tributaries, the upper Ngahauranga, and the Porirua. In 

 fig. 2 the line of the old valley is indicated as a double broken line, and 

 farther north by the line of the Manawatu Railway. Starting at the head of 

 the valley and following it northward, we may note the changes that have 

 taken place. At the head of the Silver Stream, which occupies the southern 

 end of the valley, the divide is now 1,000 ft. above the sea, and the old 

 valley appears to have continued still farther southward, the divide now 

 being rapidly pushed northward by the activity of torrents of the south coast. 

 Two miles and a half from its source the Silver Stream turns very sharply 



* Loc. cit., }). 1. 



