Smrru.— Geology of Northern Portion of Hawke Bay. 571 
Island, Napier, where it occurs at the sea level, and is there overlaid by the 
Napier limestones, which have a thickness of about 800 feet. 
Napier Limestone. 
A little further to the north at Tangoio it is somewhat less, and is divided 
by strata of dark grey clays and softer yellowish limestone. Further inland 
it again increases in thickness, being probably 300 feet deep along the 
bluffs of Purotangihia range. These limestones and associated beds form 
to the north of Napier a high broken plateau, rising at Purohutangihia to 
2,046 feet, and thence sloping gradually to the sea near Tangoio, where the 
cliffs are 250 feet high, but rising again towards the north at Matangimoe- 
moe, where the cliffs are 1,200 feet in height above the sea. The limestone 
generally has steep escarpments bounding it, often quite inaccessible. It is 
full of fossils, generally rolled and worn, principally Pecten and Ostrea. In 
some places, however, the shells are perfect, as in a branch of the Manga- 
pikopiko stream, where the bottom of the valley is strewn with large oyster 
shells in ineredible quantities. 
This limestone (if we except the much later formed deposits of shingle, 
pumice, and river terraces) is the youngest of the rocks in the district of 
which this paper treats. It has a very considerable extension to the south 
_ of Napier, reaching as far as the upper end of the Wairarapa Valley, and is 
probably of the same age as the limestones found on the southern flanks of 
the Kaimanawa Ranges on the other side of the Ruahine Mountains. That 
it has suffered very great denudation I have not the slightest doubt, as it 
gradually rose from the sea by the action of running streams, and I may 
add by the wind, which as a denuding agent is by no means to be despised, 
at all events in this part of the country. An inspection of the map (P1. XXII.) 
will show that several out-lying patches are scattered over the district, extend- 
ing inland to Maungaharuru, and northwards to Whakapunake and the 
Mahia Peninsula. All these isolated portions dip regularly towards the 
centre line of the Hawke Bay basin, and ‘with one exception the fossils are 
the same, as far as my imperfect knowledge of the subject goes. This ex- 
ception is the mass of limestone capping the hills to the east of the Wai- 
roa hiver, and extending to Whakapunake. Here the rock is composed 
almost entirely of Waldheimia shells, giving it in places a peculiar botryoi- 
dal appearance. Whether the other fossils common to the rock in other 
places are present also, I am unable to say, but I saw none in the few places 
I was able to examine. The dip of the underlying strata is also hidden in 
this part, excepting on the bluffs of Whakapunake, where the limestone 
appears to rest on the Maungaharuru sandstones, but a little to the north of 
Te Hiwera, the Papa is seen dipping south-south-west, whilst the Wald- 
heimia beds dip nearly west. At Moumoukai, on the Nuhaka River, is 
