2r>0 Transactions. 



From the absence of slipped material along the base of the Wasatch 

 Range, in Utah, Davis* argued that the slope of the spur-facets now found 

 there gives the inclination of the plane of faulting. In the case of the 

 Wellington scarp, however, it is uncertain whether a scree of slipped material 

 exists or not beneath the water and silt of the harbour. Nor can the very 

 even slope of the facets throughout the length of the scarp be taken as an 

 indication that they represent the actual plane of faulting. Their slope 

 appears rather to be " the angle of rest for the products of decay " of the 

 material of which they are composed. The writer cannot agree with Bellf 

 that the slope is steeper than the angle of rest. It is clear that many, if not 

 all. of the clearly defined, sharp-edged facets owe their actual form to wave- 

 action at their bases, the extent to which the scarp has been thus cut back 

 b?ing indicated by a narrow wave-cut platform at its foot. This, however, 

 seldom reaches a width of 40 or 50 yards, and part of it may represent a 

 levelled-off scree of slipped material. It is now almost entirely covered by 

 the railway-embankment along the shore. 



Reasons have already been given for believing that the actual movement- 

 has been subsidence of the block to the south-east (p. 258). It was 

 assumed by BellJ that the faulting movement was one of block elevation 

 and tilting towards the north-west, and the Porirua Stream was cited as an 

 example of a stream flowing down the tilted back slope of the block. There 

 is no doubt, however, that the Porirua followed its present course before 

 faulting took place. It follows one of the old strike valleys. In the valley 

 there is evidence of recent revival, but not such as would be required by a 

 tilt of the magnitude assumed ; it appears to be due solely to the general 

 movement of uplift which has affected the Wellington Peninsula, although 

 perhaps not everywhere by exactly the same amount. The drowning of the 

 lower Porirua may be ascribed to a less-extensive later tilt of a much larger 

 block of country (see p. 257). 



Other Faults. 



An origin by faulting is implied for some of the longitudinal features 

 of the Wellington Peninsula by Bell,§ and the line of the Makara Valley 

 is included by McKay|| among " active faults and earthquake rents." 

 The presence of many faults, and particularly of the last mentioned, is 

 revealed in natural sections. The three faults which McKayli describes 

 as " converging on . . . the capital of New Zealand " can be recognized, 

 although it is difficult to see why they are to be regarded as the continuation 

 of faults in the South Island. The stratigraphy of the district is too little 

 known to allow an estimate to be made of the amount of movement on the 

 fault-planes, and the period at which the main movement took place has not 

 been ascertained. It can be confidently stated, however, for the whole of 

 the area west of the Karori-Khandallah Valley that physiographic evidence 

 of recent faulting is entirely lacking (see pp. 262-61). The boundaries 

 of the subsided Port Nicholson block may next be investigated. 



On the map of Port Nicholson given by Bell** there are indicated, 

 iti addition to the Wellington fault, five other fault-lines bounding the 



* Bull. Mus. Comp. Zool., Harv., vol. 42, No. 3. 190 i, p. 15S. 



t Loc. cit., p. 536. 



% Loc. cit., p. 539. 



§ Loc. cit., section, p. 539. 



|| "Reports of Geological Explorations, 1890-91." map, p. 1 ; Wellington,. 1891. 

 •I Loc. cit., p. 19. 

 ** Loc. cit., p. 537. 



