338 Transactions. 



marls "' liave been brought opposite the coal-beds. On the south side of 

 the fault some anticlinal folding is seen ; the coal-measures occupy a middle 

 position along the fault-line, and thence to the west a complete sequence 

 up to the Amuri limestone may be traced, while to the east a similar 

 sequence up to the Waipara greensands may be seen in Boby's Creek. On 

 the north side of the fault, gentle anticlinal folding is shown by the " grey 

 marls " in Boby's Creek below the road-bridge, and synclinal folding in 

 the Main Mount Brown limestone both on the north bank of the Waipara 

 River (see Plate XXI, fig. 1) and alongside the road in the angle between 

 the fault, the Waipara River, and Boby's Creek. 



Near Waikare, where there is a low transverse depression in the main 

 elevated ridge separating the two lowland areas, the Notocene rocks have 

 not been stripped from the pre-Notoceneon the axis of the elevation, but 

 continue across the saddle, and extend into the Hawarden area. There is 

 thus anticlinal folding parallel to the elongation of the Notocene strip, but 

 the structure is complicated by the presence south of Waikare of a syncline 

 and anticline transverse to the elongation of the strip. As these folds, 

 exhibited only in the lower Notocene beds, do not continue to the south- 

 eastern side of the Weka Pass, where the upper Notocene beds outcrop, it 

 was at one time considered that they were a proof of unconformity ; but 

 the structure was satisfactorily explained by Marshall, Speight, and Cotton 

 (1911), whose diagrams are here reproduced (fig. 4). Without doubt the 

 Mo-unt Brown beds formerly extended north-west across the pass, and shared 

 the same folding, but have since been removed by erosion. 



Besides the above more important structural features there are a number 

 of minor faults, with throws from a few inches to several feet, one of which, 

 in the railway-cutting -ISf miles from Christchurch, was mistaken by Hutton 

 for an unconformity. 



Physiography. 



The main elements of the relief of the area under consideration and the 

 surrounding areas were doubtless determined by the Kaikoura orogenic 

 movements, which caused the uplifts of the high-standing blocks — ^viz., 

 Mount Grey, the Doctor's Range, Moore's Hills, and the Mount Alexander 

 Range — and the (relative) downthrow of the intermont areas of the Heath- 

 stock, the Waikare Valley, and the Omihi Valley. The drainage-pattern, 

 however, was probably established in its major outlines during the earlier 

 uplifts of which the Kowhai gravels serve as a record. The Waikare flats 

 and the Heathstock lowland are stated by Speight (1915) to be part of 

 the Hurunui-Waiau intermont depression, whit-h is drained by the Waiau, 

 Hurunui, Waikare, and Waipara Streams, each with its separate gorge 

 through the seaward-lying enclosing ranges. The lowest gap in these ranges, 

 the saddle of the Weka Pass, is not used by any stream, a proof that the 

 above rivers occupied their present courses before the uplift of these ranges 

 took place. They are, therefore, antecedent streams, or anteconsequents 

 if the earlier uplifts are admitted as only earlier stages of the main uplift. 



Following the main later uplifts fresh consequent streams would come 

 into being, the chief of those which traverse our district being the Kowhai 

 River in its main branches, the Weka Creek, and Omihi Creek. These 

 streams, it will be noticed, are widely spaced. 



In the period following the later uplifts an early mature topography 

 developed. The presence of hard bands in the Notocene sequence — viz., 

 the Amuri limestone and Weka Pass stone, the various Mount Brown lime- 

 stones, and the harder sandstones of the Greta series — led to the development 



