Marshall, Speioiit, Cotton. — Younger Rock-series of N.Z. 38 5 



ill the gorge, or along the line of strike for a mile to the north-east 

 or south-west, or elsewhere in the district any sign of uncomformitv 

 between these beds. ... At the lower end of the limestone gorge the 

 Weka Pass stone is overlaid by the grey marls. The section is clear, and 

 shows perfect conformity between the two. ... At the junction 

 between the lower part of the Mount Brown beds and the upper part of 

 the grey marls a stratigraphical uncomformity is here evident enough in 

 the section displayed." 



Park (Geol. Rep., 1883, p. 33) : " The sequence of the beds just 

 enumerated is the most complete to be found in any part of New Zealand. 

 The stratigraphy is plain and simple, being free from obscurities, and 

 offering few points of possible disagreement." At p. 35 : " At the Waipara, 

 on the other hand, the geological record is complete, the beds following 

 one another in one conformable sequence." At p. 22 : " The Weka Pass 

 stone passes gradually into the grey marls without any sudden change in 

 the character of the deposits such as is seen between the Weka Pass stone 

 and the Amuri limestone." At p. 28 : " The strata at the Waipara, where 

 the complete sequence is exposed, are quite undisturbed, following one 

 another uniformly throughout all parts of the district. ... I am 

 strongly of opinion that a complete sequence of beds exists from the base 

 of the Cretaceo-tertiary to the close of the Pareora formation." 



Very similar opinions have been expressed by the geologists in regard 

 to the series exposed in the Weka Pass. In other words, Hutton is con- 

 stantly bringing evidence of unconformity between the Amuri and Weka 

 Pass stone, and, in 1886, between the grey marls and Mount Brown beds. 

 Haast still supports a subdued unconformity between the Weka Pass stone 

 and the grey marls, while McKay and Hector (1890-91, p. 98) place an un- 

 conformity at the base of the Mount Brown beds only. Park, however, 

 in 1904 (Trans. N.Z. Inst., vol. 37, p. 542) absolutely changes his position, 

 and places an unconformity between the Weka Pass stone (Cretaceous) 

 and the grey marls (Miocene), but states that this break is nowhere to be 

 seen in section, although shown by the mapping. He also places an uncon- 

 formity between the Mount Brown and the overlying beds, which he now 

 calls Motunau (Pareora, Hutton). 



It is certainly remarkable that such a variety of opinion should have 

 been given in connection with a section that is so remarkably clear and 

 free from any obscurity. As the authors are engaged in teaching this sub- 

 ject in the colleges of the New Zealand University, and were much perplexed 

 by these statements and the still more conflicting results when correlations 

 were attempted with the series in other parts of New Zealand, it was agreed 

 to visit the Waipara and Weka Pass in company and try to arrive at a 

 conclusion that might express the actual facts and yet perhaps be 

 unanimous. The result, based on the stratigraphy alone, has been wholly 

 satisfactory, and there is an unreserved agreement. For the sake of clear- 

 ness, the unconformities described by different observers will be taken in 

 order from below upwards. 



Relation of Amuri Limestone to Weka Pass Stone. 



1. Hutton' s Unconformity. — The Amuri limestone is white and rubbly ; 

 the Weka Pass stone has much glauconite, and is compact. Hutton 

 describes the proof of unconformity as consisting of pebbles of the Amuri 

 limestone imbedded in the base of the Weka Pass stone. McKay and Park 



13— Trans. 



