Marshall. — Relations between Cretaceous and Tertiary Rocks. 103 



sequence was found which contained in the basal beds fossils of different 

 ages in various localities ; but at the same time the faunas were so related 

 in all the localities that Hector considered it advisable to place them in the 

 same series. 



This hardly seems to merit the remarks of Wilckens,* " Hector's 

 whole Cretaceo-tertiary formation, which contains pell-mell a motley col- 

 lection of Cretaceous and Tertiary fossils alongside of Jurassic and Eecent 

 plant-remains; is at least doubtful." 



Hector's work clearly shows the essential nature of the problem, which 

 is admitted by all observers: (1.) That the younger series of rocks rests 

 unconformably on an older series, whether Jurassic or Triassic sediments or 

 schists, and on these older rocks the younger series was deposited after a 

 prolonged period of erosion. (2.) The basal members of this younger series 

 of rocks are of Cretaceous age at Amuri Bluff, Waipara, Trelissick basin, 

 East Wellington, Hawke's Bay, North Auckland, and elsewhere. This is 

 amply proved by the fossils being in some cases reptilian types — Plesiosaurus, 

 Mauisaurus, &c. ; though in others merely Mollusca, such as Trigonia, 

 Inoceramus, Concliothyra, Ammonites, and Belemnites. (3.) In other localities 

 the basal fauna is as clearly Tertiary, which is generally the case in South 

 Canterbury and Otago. (4.) In those places where the basal beds are of 

 Cretaceous age they pass up into strata that are distinctly Tertiary ; but, 

 unfortunately, in any particular section, with a considerable thickness of 

 intervening beds which contain no fossil remains. 



Actually the only point at issue is whether this change of fauna is 

 associated with a stratigraphical break or whether there is a complete 

 stratigraphical conformity. Opinion based upon geological knowledge 

 and experience obtained in other countries or from reading woixld at once 

 decide on the former of these alternatives. It is only work in the field 

 in this country that has caused various geologists to adopt the latter 

 alternative, and it may at once be said that this attitude is adopted not 

 only after a close inspection of the stratigraphical sequence, but in accord- 

 ance with the lithological character of the beds, which demands a gradually 

 increasing depth of water as one rises through the series from the Cretaceous 

 to the Tertiary strata. 



(c.) Hutton's Classification. 



Hutton's position is perfectly clear, and it is certainly one that must 

 strongly commend itself to those geologists who have not visited the 

 countr}^ or who have not become personally acquainted with the problem 

 in the field. He maintained that the Cretaceous beds are separated from 

 those of Tertiary age by a distinct stratigraphical break. f In the typical 

 districts of North Canterbury, at the Weka Pass, and at the Waipara this 

 break is placed between a Globigerina limestone (Amuri limestone) and a 

 glauconitic arenaceous limestone (Weka Pass stone). The former is in 

 these localities the highest member of the unfossiliferous beds which sepa- 

 rate the beds containing Cretaceous fossils from those with a Tertiary 

 fauna. 



* 0. Wilckens, " Revision der Fauna der Quiriquina Schichten," Neues Jahrb. 

 fijr jVIin., &c., Beil.-Band xviii, p. 279. 



t F. W. Hutton, " Geological Position of the Weka Pass Stone," Quart. Joum. 

 Geol. Soc., 1885, p. 266 ; also, " Sketch of the Geology of New Zealand," Quart. Journ. 

 Geo]. Soc, 188.5, p. 207. 



