542 Prof. J. Park — Tertiaries and Cretaceous, New Zealand. 



The Cretaceous Series rests on a highly denuded surface of the 

 Palseozoic mica-schist. The Tertiary Series also rests on the mica- 

 schist and abuts against the various members of the Cretaceous Series. 



The Tertiary beds extend northward from Waikouaiti to the Shag 

 River, occupying the floor of the Lower Shag Valley, which is wide 

 and low-lying. The beds are nearly horizontal or dip towards the sea 

 at angles between 3° and 5°. Their succession has been determined 

 by bore-holes and outcrop exposures. 



The Cretaceous Series forms the steep ridges on the north side of 

 the Lower Shag Valley. Its basal conglomerates and coal-measures 

 are tilted at high angles, and, going eastward to the sea, are folded as 

 shown in Fig. 1. 



The upper beds (No. 1) contain Belemnites lindsayi, and Saurian 

 bones form the nucleus of many of the septarian boulders, many 

 of which attain a diameter exceeding five feet. Beds No. 2 contain 

 Conchothyra parasitica, Trigonia, Rostellaria. The Cretaceous facies of 

 these beds has never been disputed. 



Fh/ce - i wi- tahi 



J?ailw-a 



Cbal/Xtne. 

 i 



2 



Fig. 1. (1) Dark greensands passing down into shaly clays and sandstones 

 with numerous septarian boulders ; (2) brown sandstones alternating with 

 gritstones and pebbly beds ; (3) gritstones, loose sands, and grits, with 

 shales and coal-seams ; (4) conglomerates, mainly quartzose, passing into 

 mica-schist breccia at base ; (5) mica-schist. 



The nearly horizontal Tertiary strata, on the other hand, that abut 

 against the tilted and folded Cretaceous Series contain only the typical 

 Lower Tertiary fauna of the Oamaru Series. Moreover, the large 

 septarian concretions that are so characteristic of the Cretaceous beds 

 are absent. The thickness of the tilted and folded Cretaceous strata is 

 2,200 feet, and of the adjoining horizontal Tertiaries 1,200 feet. 



Sir James Hector, in 1862, before the Cretaceo-Tertiary theory was 

 thought of, in a beautiful coloured geological map of North Otago, 

 now in the Otago University School of Mines, showed the horizontal 

 Tertiaries resting unconformably on the Shag Point Cretaceous Series 

 as they are seen to do in the field. This relationship is shown in 

 Fig. 2. 



The authors state that the unconformity shown in my section 

 {Geology of New Zealand, p. 116) is a matter of inference, as no 

 outcrops could be found in the estuary. This was apparently an 

 oversight on their part as the Tertiary rocks form the low banks 

 of a branch of the Shag lliver near the mouth, well within the 

 influence of the tidal flow. 



