BanrRUM.—Geology of Riverhead-Kaukapakapa District. 143 
Since outcrops are relatively scarce it is perhaps desirable to record 
of Waitoki Stream eastwards of Wainui Hill. Again, in cuttings of the 
Parakakau-Silverdale Road a shaly red and grey claystone facies appears. 
It is steeply tilted, and strikes approximately north-east and south-west. 
Near White Hills, especially along the road leading south-east from the 
hite 
siliceous mudstone phase of the beds. North-westwards of the school, at 
the distance of about a mile along the track to Parakakau, a massive 
relatively resistant limestone is exposed, whilst about three miles westward 
of White Hills School a pure limestone is exposed in a quarry opened 
. up for agricultural lime about a quarter of a mile north of the road to 
Kaukapakapa 
Onerahi beds probably occupy most of the district east of the Silverdale — 
Dairy Flat Road as far south as Dairy Flat, where limestone outcrops at 
the road near where it crosses the upper north- ont: branch of Rangitopuni 
Stream and also south-westwards in grass-lands on the right bank of this 
tributary. 
It can next be found, continuing in a south-west direction, in Rangi- 
topuni Stream below its confluence with the tributary just mentioned. 
Near Escot's house it is represented in the material dug from a well, though 
aitemata sandstones shortly appear in a rill about 10 chains south of the 
house. South and south-westwards of Escot's there are two inliers of 
white indurated mudstones which must be referred to the Onerahi series. 
One is inconspicuously exposed in a trench cut many years ago for a mill- 
race on the right bank of Gibbs Creek about 300 yards above its confluence 
with Rangitopuni Stream. The other is represented by a number of 
outcrops in a belt over a quarter of a mile in width on the divide at the 
head of the same creek. Siliceous replacements of wood are common on 
the gum-track following this divide. 
Finally, a small isolated area showing not only limestone but other 
phases is recognizable by fragments turned up in some post-holes, and by 
actual outcrops in the headwater basin of a small north-west-flowing stream 
a little south-west of Wray’s house at Horseshoe Bush. Waitemata beds 
great distance eastwards, and can shortly be recognized northwards from 
the Onerahi limestone in imperfect outcrops furnished by slips adjacent to 
the road giving access to Wray’s property. 
Relations to other Serves. 
Actual num. between the Onerahi strata and the overlying Waite- 
mata rocks have not been discovered, though in several instances rocks of 
the two series Me been found in close contiguity to what must be the 
actual surfaces of contact. In some instances the Waitemata beds ap- 
parently next above the Onerahi ics are sandstones, in others they are 
conglomerates, a condition that might be expected with deltaic beds. The 
mentary, and i ot unusu pebbles of а Globigerina ooze 
microscopically indistinguishable from similar material composing Onerahi 
limestones, whilst fragments of other sediments comparable with other 
phases of the Onerahi beds often abound. Cox (1881) states that Hector 
