SurrB.—Geology of Northern Portion of Hawke Bay. 565 
Art. LXXXVIIT.— Sketch of the Geology of the northern portion of the Hawke 
Bay. By 8. Percy Smita. 
Plates XXII., XXIII. 
[Read before the Auckland Institute, 27th November, 1876.] 
Te following notes have reference to the country lying to the northwards 
of the town of Napier, extending along the coast of Hawke Bay to the Mahia 
Peninsula, and inland for a distance of from 15 to 25 miles, as is shown 
upon the accompanying map 
The geology of this part of the North Island is tolerably simple. It 
forms part of a large elongated basin occupied by rocks of the tertiary age, 
called by Dr. Hochstetter the * Hawke Bay series," but now I believe in- 
cluded in the Ahuriri formation of Captain Hutton,* and includes also 
rocks of an older date, all of which have been deposited on the flanks of 
the slate mountains found a few miles further inland. The greater part of 
the eastern edge of this basin has been gradually eaten away and removed 
by the action of the sea, but in the northern part of the distriet the westerly 
dip of the beds shows that part of the ancient margin is here preserved. 
This may also be seen a little further south, near Cape Kidnappers, where 
the strata all dip towards and under the Ahuriri Plains. A line drawn from 
near Napier in a north-easterly direction to the falls at Te Reinga on the 
Wairoa River, will very nearly coincide with the synclinal axis of the basin, 
towards which the strata on either side regularly dip, Scinde Island being 
part of the youngest formation present. 
I very much regret that owing to want of time I was unable to carry 
my sections a few miles further westwards, so as to show the relation be- 
tween the rocks here described and the old slate rocks forming the axis of 
the island, and which extend uninterruptedly from Wellington to the East 
Cape, forming the Tararua, Ruahine, and Urewera mountains. To any- 
one accustomed to the shapes presented by mountains of this class of rock, 
however, there is no mistaking their appearance as seen even from a dis- 
tance of several miles. Their positions therefore will be indicated on the 
accompanying sections with tolerable accuracy. 
That an extensive series of stratified argillaceous and sandstone rocks 
exists between the lowest beds shown on Section No. 1, Plate XXII., and 
the slate ranges at Huiarau is evident from the appearance of the country 
looking westward from the high mountains surrounding Lake Waikare- 
moana, where every here and there the white surface of the rock has been 
exposed on the hill sides by land slips. 
* See introduction to “ Catalogue of Tertiary Mollusca,” Wellington, 1873. 
