1918.] 
The N.Z. Journal of Science and Technology. 
147 
terrace of this kind bordering the Ivekerangu River 
Fig. 4 shows a broad 
near its mouth. 
Such terraces are common in New 
Zealand valleys. Near Seddon, for 
example, broad terrace plains border 
the Awatere River on each side. 
Their combined width is about three 
miles, and their height above the 
present river-bed about 120 ft. In 
addition, terrace remnants hundreds 
of feet higher are numerous on the 
valley-sides, bearing witness to the 
occurrence of more than one cycle of 
erosion. Similar terraces occur in the 
valleys of the Rangitikei and neigh¬ 
bouring rivers of the North Island, and 
in the rivers of eastern Wellington. 
Such terrace plains and remnants 
were recognized in New Zealand by 
Hochstetter in 1859. They are found 
principally in areas of soft rocks, upon 
which rivers attained an advanced 
stage of maturity in each cycle of 
erosion, though this was by no means 
the case in adjoining areas of resistant 
rocks. 
Fig. 5.—Terraces of solid rock and of 
alluvium. 
Terraces of Rock and of Alluvium .—Terraces are often formed of solid 
rock with a thin veneer of gravel on the top — the gravel of the former 
valley-floor. Such terraces are illustrated in fig. 5, B, developed from the 
valley-plain A. When, however, terraces are remnants of aggraded valley- 
plains (fig. 5, C) they may be composed of gravel throughout (D), or of 
solid rock below and a thick mass of gravel above (E). 
[C. A. Cotton, photo. 
Fig. 6. —Rock terrace in the valley of the Wairoa River, Nelson. 
