282 C. A. Cotton — Block Mountains in New Zealand. 



erablj steeper than that of the Pool Burn. This difference is 

 dne to the much greater load of waste Avhich the northern 

 stream has to transport, and which comes from the great fanlt 

 scarp of the grejwacke highland. The little dissected schist 

 platean from which the Pool Burn flows supplies a relatively 

 small quantity of waste. 



The numerous parallel, southward-flowing, consequent streams 

 in the northern or Maniototo Plains portion of the Maniototo 

 depression are exactly similar in their gradients and their 

 arrangement to the streams of the northern end of the Ida 

 Yalley depression. The Ida Burn and the Wether Burn are 

 separated by a narrow interfluve consisting of the outcropping 

 undermass of a northerly continuation of the Pough Pidge 

 block. The Wether Burn and the other similar streams form 

 the northern members of a centripetal consequent system in 

 the Maniototo depression and are tributaries to the Taieri Piver. 



Those streams also consequent on the deformation, which 

 enter the depression from the schist npland plateau to the south, 

 like the Pool Burn, flow with verj^ gentle gradients across the 

 wide valley plain which there forms the floor of the depression. 

 The chief of these, the Upper Taieri, wanders freely, and 

 oxbow lakes abound upon its flood plain. As a result of the 

 steeper gradient of the northern streams owing to larger supply 

 of waste, the east-and-west axis of the lowland in the Maniototo 

 depression has been pushed far to the south. 



The drainage of this depression finds an outlet by way of the 

 Taieri Piver into the Strath Taieri depression, crossing the area 

 of mature dissection around the northern end of the Pock and 

 Pillar block in the fault angle betw^een that block and the 

 Kakanui fault scarp to the north. This portion of the course 

 of the Taieri is probably consequent on the deformation, being 

 determined either by the spilling over of a consequent lake in 

 the Maniototo depression or cut down during slow deformation. 

 The fluor of the depression was obviously much higher in an 

 early stage of the cycle before part of the overmass had been 

 removed. It is unnecessary, therefore, to suppose that the 

 present rather young gorge was cut contemporaneously with 

 the deformation. Its cutting must, however, have gone on 

 while the floor of the Maniototo depression was being excavated 

 to its present depth. 



The southwesterly course of tlie Taieri Piver through the 

 Strath Taieri depression is obviously consequent on the defor- 

 mation, as also are most if not all the larger tributaries this river 

 receives in its course across the Barewood plateau. The course 

 of the Taieri Piver itself in a southeasterly direction across the 

 plateau appears to be consequent, as it follows the lowest sag 

 in the surface. It is graded, or almost so, with a gradient of 



