10 Transactions. 



VII. North Canterbury. 



1. Waipara and Weka Pass District. — -The Waipara - Weka Pass district 

 has been frequently examined, and much has been written concerning sup- 

 posed unconformities at various horizons from early Tertiary upwards. 

 In 1869 Hector published some brief remarks on the geology of the Waipara 

 district (1, pp. x-xiii). He mentions an unconformity which on Hutton's 

 authority is to be understood as occurring between the Grey Marl and the 

 Mount Brown beds, though the description might almost equally well apply 

 to the contact of the Amuri limestone with the Weka Pass stone (see also 

 39, p. 413). McKay and Park (in early reports) also place a stratigraphical 

 break at this horizon. The evidence, however, appears to be very slender, 

 and probably at most justifies the opinion that only slight local unconformity 

 is present.* This seems to be the opinion of von Haast (1a, pp. 14, 16 ; 

 21, p. 306), who also in his earliest report suggests a local unconformity 

 above the Grey Marl (1a, p. 17).t 



In 1877 Hutton describes in clear terms what he believes to be the un- 

 conformable junction of the Weka Pass stone with the underlying Amuri 

 limestone (3, pp. 43, 44). In 1885 he repeats this statement, with additional 

 data in its favour (24, pp. 269-70). Hector, in his Progress Report of 

 1877 (3), expresses his inability to convince himself of the unconformity. 

 Von Haast in 1879 discusses the question, and decides that there is no break 

 of any consequence, but, somewhat strangely, does not refer to the views 

 of other observers (21, pp. 297-98). In 1887 (13, pp. 78 et seq.) and in 1892 

 (16, pp. 98, 102) McKay unequivocally opposes the supposed unconformity. 

 Park in 1888 perceives evidence of change in the conditions of deposition, 

 perhaps accompanied by a degree of elevation, but not of true unconformity 

 (14, pp. 28, 31, &c.). "in 1904 Park agrees with Hutton (39, p. 413), but 

 in 1905 shifts the unconformity to the upper surface of the Weka Pass stone 

 (41, pp. 542, 546). Marshall, Speight, and Cotton cannot see any evidence 

 of unconformity in the younger rock-series of the Waipara and Weka Pass 

 districts. In 1912 J. A. Thomson observes " apparent conformity in section 

 throughout the Waipara district " (52, p. 8). Owing, however, to palaeonto- 

 logical evidence of the Tertiary age of the Weka Pass stone having been 

 discovered — or, rather, rediscovered — by Thomson and Cotton, Park in 1912 

 returns to Hutton's view (50, pp. 496-97). An examination lately made 

 by the writer has convinced him that the upper surface of the Amuri 

 limestone has been eroded, and that local unconformity (disconformity) at 

 least is present (63, p. 92). On palaeontological grounds there is reason 

 for believing that the unconformity represents a considerable time interval. 

 Further evidence, however, is required before one can assert with any 

 degree of confidence that the break extends from the Cretaceous to the 

 Oligocene or Miocene, as inferred by Hutton and Park. 



2. Motunau (Stonyhurst) District. ■ — ■ In 1877 Hutton shows an uncon- 

 formity at Motunau between Amuri limestone and Tertiary rocks (3, sec- 

 tion vi, opposite p. 56), and in 1885 gives further data (24, pp. 270-71). 



* Since this was written the writer has seen clear evidence of at least a local uncon- 

 formity between the Grey Marl and the Mount Brown b^ds in the vallej' of the Weka 

 Creek. 



t Von Haast's section of 1871 (1a, opposite p. 18) shows violent unconformity near 

 Boby's Creek between the Grey Marl and underlying beds. A faxdt, however, is the 

 cause of the structure interpreted by von Haast as an unconformity. (See 14, section 

 on p. 30, and map opposite same page.) 



