Thomson. — Geology of Middle Waipara and Jl'eka Pass District. 399 



diastropliic history of the whole of this province appears to have been as 

 follows : Emergence of the pre-Notocene rocks during Clarentian, Piri- 

 pauan, and Kaitangatan, ending with peneplanation : submergence with 

 sedimentation in the Ngaparan or Waiarekan, attaining its maximum in 

 the Ototaran ; a cessation of sedimentation before the deposition of the 

 Hutchinsonian, perhaps due to standstill of land and sea, during which a 

 phosphatization of the upper surface of the Ototara limestone took place ; 

 gradually shallowing of the sea during the Hutchinsonian and Awamoan, 

 followed by emergence at the end of the Awamoan ; deposition of terres- 

 trial gravels during the Wanganuian ; block-faulting, with tilting of the 

 Oamaruian and Wanganuian beds about the close of the Wanganuian. 



The jMiddle Waipara and Weka Pass district, on the other hand, forms 

 part of a diastropliic province extending from the Rakaia River to Kai- 

 koura Peninsula. The stratigraphical sequence is not so constant as in the 

 southern province, owing to aii overlap traceable in the older beds, and 

 there are still large parts of the province that have not been described in 

 detail. The diastrophic history appears to have been as follows : Emer- 

 gence of the pre-Notocene rocks during the Clarentian, without complete 

 attainment of peneplanation ; partial submergence and sedimentation 

 during the Piripauan and Kaitangatan, with progressive overlap on the 

 diversified surface ; a cessation of sedimentation before the deposition of 

 the Oamaruian, probably due to a standstill of land and sea, during which' 

 a phosphatization- of the Amuri limestone took place ; renewed depression 

 of the Amuri limestone and the old land, leading to an overlap of the Weka 

 Pass stone over the Piripauan and Kaitangatan on to the now peneplaned 

 pre-Notocene (lower Oamaruian) ; shallowing of the Oamaruian sea with 

 oscillations of movement during which the " grey marls " and Mount Brown 

 limestones were deposited, with interformational unconformities (upper, 

 Oamaruian) ; uplifts, perhaps of the nature of block movements, exposing 

 fresh areas of pre-Notocene rocks to rapid erosion, with deposition of the 

 Greta beds (early Wanganuian) ; uplifts, with folding or tilting and erosion 

 of the whole marine Notocene, 'and deposition of the terrestrial Kowhai beds 

 (late Wanganuian) ; block-faulting about the close of the Wanganuian, with 

 renewed folding or tilting of both the marine and terrestrial Notocene series. 



The diastrophic histories of these two areas are thus seen to be markedly 

 dissimilar. In the northern province marine beds, both older and younger, 

 are developed which have no counterpart in the southern ; the nature of 

 the beds of correlative age (Oamaruian) is different in the two areas ; and 

 the relationship of certain beds is different. The greatest difficulty in the 

 geology of each area is the nature of the conditions which permitted phos- 

 phatization of the upper surfaces of certain limestones. Whatever these 

 conditions were, they happened at different times in the two provinces. 

 The stratigraphical unity within the boundaries of each province, and the 

 diversity between the two, are salient facts that demand recognition. 



Two of the classifications proposed for the younger rocks of New Zea- 

 land have failed to recognize the existence of the diversity of stratigraphical 

 and diastrophic history in the above and other provinces — viz., the 

 Cretaceo-Tertiary classification of Hector and the single rock-series classifi- 

 cation of Marshall. In each of these a supposed uniformity of stratigraphy 

 has been assumed by the mistaken correlation of the Amuri and Ototara 

 limestone^. The majority of the other classifications — those of Hutton, von 

 Haast, Park. Morgan, and Woods — recognize the distinctness of these lime- 

 stones, and therefore part at least of the diversity of the above provinces, 

 but explain the facts by postulating important earth-movements between 



