Morgan. — Records of Unconformities in New Zealand. 15 



much more likely explanation of discordant contacts than unconformity 

 as supposed by the observer. The irreconcilably opposing interpretations 

 of critical sections offered by the several groups of workers add much to 

 the difficulties of the student, and, combined with i\\Q knowledge that 

 various errors have been made, induce a spirit of scepticism, and incline 

 him to reject the observations made by those with whom he happens not 

 to be in sympathy. Until, however, the field exposures and other data 

 upon which past observers relied have been critically re-examined it would 

 be a mistake to follow such an inclination. Various examples of older work 

 being cast aside by a later investigator (who in some cases was also the 

 original observer), and subsequently found to be practically correct, could 

 be cited. 



The following conclusions have been reached by the writer : — - 



(1.) That there are various local unconformities in the rock-successions 

 discussed. Some investigators have hastily assumed one or more of these 

 to be major unconformities, whilst others have denied their existence alto- 

 gether. 



(2.) That, since in no locality are marine Cretaceous rocks known to be 

 in contact with marine Eocene rocks, no definite opinion as to the existence 

 or non-existence of unconformity between Cretaceous and Eocene can be 

 formed. The absence of such contacts, however, favours unconformity. 



(3.) That in all parts of New Zealand there is a decided unconformity 

 between the Miocene and any Eocene or older rocks present. The evidence 

 for this is most unmistakable in North Auckland and on the west coast of 

 the South Island. 



From these opinions it also follows that — ■ 



(4.) The Cretaceo-tertiary theory of Hector is untenable as a working 

 hypothesis applicable to all New Zealand; for, although proof of uncon- 

 formity between the marine Cretaceous and the marine Eocene is still 

 wanting, evidence of conformity is equally far to seek. In any case, the 

 inclusion of the whole or the greater part of Hutton's Oamaru System in 

 the Cretaceo-tertiary is an error which has led to great confusion. 



(5.) In like manner the modification of the Cretaceo-tertiary hypothesis 

 advanced by Marshall, Speight, and Cotton is unsustainable, for uncon- 

 formities do exist between Cretaceous and Pliocene, and, moreover, the 

 investigators named have made various extremely questionable correlations. 

 On the other hand, they show considerable respect for palaeontological 

 evidence, have disproved various erroneous correlations of other writers, 

 and have clearly demonstrated the essential unity of the Oamaru and Pareora. 

 systems of Hutton. 



(6.) In those localities where the unconformity reported by Hector 

 and his colleagues between the Cretaceo-tertiary and the Eocene happens 

 to coincide with the lower limit of the Miocene rocks it has a real existence, 

 but elsewhere is either non-existent, or local, or requires further investi- 

 giition. 



(7.) The unconformity frequently reported by the old Geological Survey 

 between the Eocene and the Miocene generally coincides with the boundary 

 between Hutton's Oamaru and Pareora systems, and therefore is either non- 

 existent or is represented only by a slight local unconformity. 



(8.) Hutton may or may not have been right in placing an unconformity 

 at the top of the Cretaceous. He was right, however, in placing an uncon- 

 formity at the base of the Oamaru System or Series. 



