620 



Transactions. 



Miilgan,* and Fox,t pass conformably up into the Manukau breccias — a 

 series of volcanic agglomerates and breccias of extensive development on 

 the west coast north of the Manukau Heads. It is evident, therefore, that 

 the Coal Point Series is to be correlated with the Manukau and Whangaroa 

 breccias and the strata which conformably underhe these breccias. It 

 may be noted that petrologically the component rocks of the Coal Point 

 and Whangaroa breccias show a striking similarity, and that this resem- 

 blance seems also to extend to the Manukau breccias and other closely 

 related volcanic beds of the Auckland Isthmus. J 



In this connection the two following analyses of general samples — 

 (1) of fragments of Coal Point breccia, (2) of fragments from breccia at 

 St. Pavd's, Whangaroa — may be of interest : — 



100-00 



100-00 



Since no unconformity has been recorded between the Coal Point and 

 Rahia Series, it is quite possible that the latter will ultimately prove to be 

 of Miocene age, just as the Waitemata beds, at one time considered to be 

 Cretaceo-tertiary, are now generally admitted to be conformable to the 

 Manukau breccias, and Miocene in age ; but further field study will be 

 necessary before any definite opinion can be given on this point. 



Older Debris. 



Under this heading we propose to place a series of horizontally stratified 

 sands and water-worn gravels that outcrop at various places in the area. 

 The relation of these beds to the Coal Point Series is not clear, but they 

 lie unconformably on the Rahia and older series. 



The rocks of the Rahia Series are seen at the southern end of Raliia 

 Bay to be unconformably succeeded by a horizontal layer of fine gravel 

 6 ft. or 7 ft. thick, followed by 100 ft. or more of horizontal sandstones. 

 In various places throughout the Aupom*i Peninsula — as, for instance, on the 

 track from Hukatere to Hohoura — similar beds, horizontally stratified, are 

 seen cropping out of the newer drifting sands. At Scott Point they may be 

 observed filling up the irregularities in the much-dissected older igneous 

 rocks, and forming a flat-topped hill, rising 300 ft. or 400 ft. above sea-level. 



* Trans. N.Z. Inst., 1901, p. 429. 



t Trans. N.Z. Inst., 1901, p. 492. 



% See Mulgan and Fox, loc. cit. ; also Marshal], Trans. N.Z. Inst., x], 1907, p, 

 Hypersthene, which Jlarshall finds so widelj- distributed in the Manukau breccia 

 not invariably present in sections of Coal Point breccias. 



96. 



las. 



