142 Transactions. 
DETAILED STRATIGRAPHY. 
1. ONERAHI SERIES. 
Petrography and Distribution. 
The facies of the rocks included in this series ranges from a Globigerina 
ooze containing over 84 per cent. of calcium carbonate to indurated siliceous 
mudstone in which there is no trace of organic remains, or to bufi- and 
pink-coloured claystones. The component members of the series are there- 
fore peculiarly difficult to diagnose stratigraphically with any certainty. 
Similar variations are usual in most of the more northerly occurrences of 
the rocks of the same series. The tests of Globigerina are numerous, but 
yet has been unable to classify. Marshall (1916) has previously described 
similar siliceous marine organic remains from the “ hydraulic limestone ” 
near Batley, in the Kaipara district. 
It has been found impossible to determine any regularity of structure 
in the Onerahi rocks. They are exposed comparatively rarely, and the 
claystones alone show definite bedding-planes. What evidence is available 
indicates that they are complexly disturbed, and are often crossed by zones 
of shattering. 
Makarau. 
Stratigraphically the inclusion of these areas of rock in the Onerahi 
series raises difficulties which are non-existent if they are placed with the 
aitemata rocks. In a wide examination of undoubted Waitemata strata, 
however, the writer i 
Cox (1881) does 
Waitemata beds. 
e main occurrence of Onerahi beds is to be found south-eastwards 
of these outcrops of uncertain horizon. It begins immediately east of 
Wainui Hill, and extends south-eastwards through Parakakau Settlement 
beyond the limits of the area described in this paper. A few small inliers 
exist farther south 
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