MARSHALL AND Murpocu.—Rocks of Wanganui-South Taranaki Coast. 155 
The Tertiary Rocks of the Wanganui — South. Taranaki Coast. 
By P. MansHaLL and К. Мовросн. 
[Read before the сене Philosophical Society, 11th December, 1922 ; received by Editor, 
December, 1922 z~ issued separately, 26th May, 1924 .] 
Iw various publications during the last few years we have endeavoured to 
solve the faunal and stratigraphical relations between the various members 
Stream the dip of the rocks is such that older and older strata, are e gradually 
exposed as one goes north and west. The strike of the strata, however, 
bends so far to the west that north of the Tangahoe the strata exposed 
on the coast-line become gradually younger, and Tepeat the series exposed 
between Patea and that place, though they are somewhat more fossiliferous. 
At the mouth of the Waingongoro Stream, some four miles north-west 
of Hawera, the old post-Pliocene surface of erosion approaches closely 
to the present NE adis and almost the whole height of the cliffs consists 
of detritus from Mount Egmont. At the base of this material there is in 
places a well-preserved shell-bed, the presence of which shows clearly that 
at the time the volcanic activity of Mount Egmont commenced the post- 
Pliocene surface of erosion was the floor of a shallow marine area. The 
absence of shell-bearing horizons at higher levels in the volcanic material 
shows either that elevation of the old sea-floor took place when the volcanic 
activity began, or that the sea was so shallow that the volcanic matter 
which was deposited soon accumulated to such a thickness as to build up 
a land surface. At the mouth of the Waingongoro Stream it is clear that 
the old fossiliferous surface had been elevated to a higher level than the 
ce 
Valley. About 300 yards north of the Waingongoro Stream there is a 
similar abrupt appearance of papa, which marks the cliff boundary of the 
old valley in this direction. It is thus evident that previous to the 
resen n 
telling how far below the present sea-level the old floor of the valley lay. 
The depression of this old floor took place, and the land-level sank until 
the tops of the cliffs that then bounded the valley were submerged, when 
a beach-deposit with Recent marine shells was formed ; volcanic detritus 
as, however, subsequently carried to the sea in such "quantity that the 
shell-deposit ceased. 
