Cotton. — Notes on Wellington Physiography. 



249 



Forms of the Kaukau Cycle. 



Kaukau* Peak (1,465 ft.) may be taken as a sample of a form be- 

 longing to the first, or Kaukau, cycle. An area of about 50 acres at 

 the summit presents the appearance of mature topography, with gently 

 rounded outlines, which abruptly give place to precipitous slopes, rocky 

 crags, and torrent-ravines, forms of the next cycle. The small, gently 

 graded valleys of the summit are transformed within a few yards into 

 torrent-courses with rock beds and steep rock walls. There is no differ- 

 ence of rock-strength to account for the change, but summit and sides 

 alike are composed of the most resistant type of strong greywacke, 

 traversed by few joints. 



In fig. 3 the slopes of the summit of Kaukau are seen in the fore- 

 ground. The surface is littered with blocks of the greywacke, weathering 

 in the manner generally regarded as characteristic of igneous rocks rather 

 than of sedimentary rocks. 



&^' 



Fig. 3. — View of the East Branch of Ohariu Stream, looking Northward from 



the Summit of Kaukau Peak. 



A graded reach, at its lowest point 250 ft. above sea-level, and incised about 50 ft. below 

 the graded valley-floor of the earlier cycle. 



Little is left of the surface belonging to the Kaukau cycle, and per- 

 haps the most extensive remnant is a tableland nearly a square mile in 

 extent, standing 950 ft. above sea-level, which exists on the divide west 

 of the Makara Stream. In fig. 2 it is marked P. It has an undulating 

 surface of mature valleys and rounded spurs, appearing from a distance 

 perfectly plane. It is bounded on all sides by the slopes of young ravines 

 eating into it. 



Many of the higher ridges show very similar topography, though no 

 other is so nearly plane. From these observations it appears that during 

 the Kaukau cycle the stage of maturity was reached, and that this nearly 

 plane area, P, stood not far above base-level. The height of Kaukau 

 and other peaks above it shows that the relief remained fairly strong. 



It is not probable that this cycle was the one which began when the 

 folded range first rose above the sea, for planation might be expected to 



* Locally pronounced Caw-caw, and spelt on some maps Kaka. 



