HuTTON. — Geology of the Waihao Valley, 



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I have elsewhere examined Mr. McKay's statements as to 

 the age of the greeusauds at Maerewheuua and Wharekauri,* 

 and I will liere only remark that he gives no evidence to show 

 that they are the equivalents of the greensands at Waihao. 

 Indeed, miless his Nantilus danicus is Aturla zkzac, he does not 

 mention a single species common to both. For the present, 

 therefore, the position of the Maerewhenua greensands cannot 

 be taken as furnishing any evidence of the 

 age of the greensands at Waihao. 



With reference to the first part of the para- 

 graph I have quoted, not much weight can 

 be attached to the position of the " ])eculiar 

 fucoidal band," which is not mentioned else- 

 where by Mr. McKay, and if unconformably 

 overlain, could not always form the top of 

 the greensands here. The evidence for the 

 unconformity really rests on the absence of 

 the Waihao limestone at this place, although 

 found half a mile off. This, however, proves 

 nothing ; because it is the relative position 

 of the limestone and the greensands which 

 is the doubtful point ; and to introduce an 

 unconformity into the section because the 

 limestone is absent, is to assume as true the 

 very point which it is wished to prove. 

 ^ Another exposure of the Oamaru System 

 J occurs on the right bank of the Waihao 

 I Eiver just before it enters the plains. The 

 . rocks here are much obscured, and I failed 

 ^- to make out the section given by Mr. McKay. 

 . To me it appeared more like an inlier, 

 ■H surrounded unconformably by the Pareora 

 ^ System. According to Dr. von Haast, the 

 § Pareora System fills up valleys denuded 

 •g out of the Oamaru System north of 

 ^ Elephant Hill,! and there is no difficulty 

 ^. at all in supposing that these Pareora rocks 

 ^ cross both the south and north branches of the 

 Waihao, and wrap round the rocks of the 

 Oamaru System as far as the Waimate Hills. 

 The annexed woodcut illustrates my view 

 of the relation of the rocks, but it is of 

 course to some extent hypothetical, as no 

 positive stratigraphical evidence is available. 



* " Quar. Jour. Geol. Soc. of London," vol. xli., pp. 558 and 562. 

 t " Geology of Canterbury and Westland," Sheet of Sections No. 5, 

 Section No. 4. 



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