96 Transactions. 



higher region to the north-west. The Tertiary beds here consist of the 

 following : — 



4. Limestone, passing down into 



3. Calcareous breccia with volcanic fragments. 



2. Volcanic tuffs and ash-beds. 



1. Sands with concretionary layers. 

 The lower parts of these probably contain coal, seeing that an adjacent 

 stream is called Coal Creek. (See also Haast, 1871, p. 30.) The limestone 

 is crystalline in texture, but shows traces of bryozoan forms on its 

 weathered surfaces. The strata are bent up into a sharp syncline whose 

 axis runs north-east, the remnant now existing being less than a mile 

 in length and 300 yards in breadth. The underlying beds are naturally 

 existent over a somewhat wider area, and extend across the Mandamus 

 towards the Hurunui, the direction of one of the reaches of this stream 

 corresponding in alignment and direction to that of the axis of the syncline. 

 The limestone has evidently been squeezed up by folding movements 

 and has occupied the structural basin in which it lies, but the form of the 

 land surface on which the limestone was laid down was not basin-shaped. 

 There are similar basins in the country to the north-west, with parallel 

 orientation, which do not now contain limestone outliers, but their form 

 is so characteristic that their origin is probably similar to that of the 

 Dove. These parallel elements may explain the north-easterly direction 

 of the Hurunui in this part of its course, for after it leaves Maori Gully 

 it apparently follows the line of these basins, with breaks across from one 

 to another. 



It may be noted also that the hills in this part of the valley rarely exceed 

 3,000 ft., but immediately to the north-west mountains rise to between 

 5,000 ft. and 6,000 ft., the marked difference in height being perhaps due 

 to the fact that the lower area was faulted down along a line of settlement 

 parallel to those occurring a short distance away in the Hanmer area and 

 still farther away in the Kaikouras. 



The indications certainly point to this submontane area having been 

 covered with a veneer of sediments during Tertiary times ; that it was 

 raised with some faulting, and certainly with folding, in late Tertiary or 

 in Quaternary times, the folding producing anticlines and synclines of the 

 beds of limestone with a general north-easterly trend ; and that these 

 limestones were removed from the basins with the exception of that of 

 the Dove. The drainage which now occurs may be called, as Cotton has 

 suggested (1917, p. 253), " anteconsequent," in that it was perhaps conse- 

 quent on the former land surface, but antecedent as far as the present 

 surface is concerned. The determining factors of the original consequent 

 drainage must in this case be highly speculative and almost impossible to 

 determine. 



(2.) Hurunui-Waiau Basin. 



The salient features of the Hurunui-Waiau basin have been mentioned 

 before by myself (1915, pp. 347-48). The formation of this mountain- 

 ringed area is attributable primarily to faulting or folding movements, or 

 a combination of both, for there is ample evidence that both are present. 

 The Tertiaries on the north-west side of the basin lie on the basement beds 

 of greywacke with a general dip to the south-east, but with occasional 

 reversals where they abut against the older rocks. This is specially well 

 seen near the road past Mount Mason into the Virginia country, where the 

 limestones in close proximity to the greywackes experience a sharp fold 



