PROCEEDINGS OF SECTION ©. 431 
About five chains south of the mill, following the beach in the 
direction of the Thames, this felspathic rock is followed by an 
intensely hard greenish-coloured volcanic breccia, often containing 
large rounded boulders or masses of andesite, numbers of which 
occupy the beach for a further distance of five chains. This 
breccia frequently passes imperceptibly into a fine-grained green 
tufaceous sandstone, which, at a casual glance, might be mistaken 
for a solid lava or dyke rock. Like the underlying grey felspathic 
rock near the mill, these rocks decompose to a considerable depth 
into rusty-coloured sands and clays. About three chains past the 
second point the breccias rest upon a highly-denuded surface of 
blue and grey-ribboned slaty shales. Near the point of contact 
the breccias contain small rounded fragments of blue shale and 
jasperoid quartz, as well as numbers of large well-developed 
crystals of iron pyrites. 
The old rocks consist of hard blue and grey slaty shales, 
showing very distinct lines of stratification. Their strike is 
somewhat irregular, the dip varying from 8.S.W. to W.S.W. at 
angles of 26 deg. or 30 deg. They are exposed on the beach at 
highwater mark, their outcrop measuring about 60 feet by 100 
feet. At low-water mark they are seen to be interbedded with, 
and to pass upward imto, grey and yellowish-coloured silicious 
mudstones, which dip 8.S8.W. at angles varying from 45 deg. to 
70 deg. The actual point of junction can be seen to great advan- 
tage on the beach, between high-water and low-water marks. At 
their base the mudstones are of a bluish-grey colour in the solid, 
weathering to a pinkish-grey on the surface. They are highly 
pyritous, and are interlaminated with thin layers of grit, 
consisting of small rounded particles of hard mudstone, mostly of 
uniform size. The ribboned shales contain similar grit layers 
near their upper surface. 
Passing southward, the fine-grained silicious mudstones rise into 
steep rugged cliffs, and form Rocky Point itself. About three 
chains past the point they terminate abruptly, and are followed 
unconformably by very hard green tufaceous sandstones, 
containing small angular blue slaty fragments. At the mouth of 
Waiohanga Creek may be seen large boulders of these sandstones, 
containing angular masses of blue shale. These boulders were, 
no doubt, brought down by that stream, which cuts across the 
outcrop of the older rocks in the upper part of its course. 
On the beach near Waiohanga Creek the tufaceous sandstones 
are intersected by a number of parallel veins, many of which are 
filled with material derived from the enclosing rock. They 
strike N.E-S.W., and are generally standing vertical. The 
two largest veins are four inches and six inches in width 
respectively. The smaller of these divides near high-water mark 
into two distinct veins, one of which joins the larger. 
