Ponp.—On the Pottery Clays of the Auckland District. 445 
bore holes put down by Mr. Ninnis at Drury, which show a depth of 69 and 
64 feet respectively through clays of many colours from white to brown, the 
seams varying from 1-11 feet in thickness. A few months since I paid a 
visit to these bore holes, but there is little to see beyond the position in 
which they were sunk. To obtain a knowledge of these beds, however, 
it will be found, by skirting the Karaka estuary on both sides from the ferry 
to Papakura and Drury, that many fine sections can be obtained of the clays 
in situ, most of them having but little overburden, and stripping will not be 
so serious a matter as at the bore holes indicated by Dr. Hochstetter. In 
some places there are 30 feet of clays, in three or four distinct beds, differ- 
ing slightly in their chemical composition though more or less varied physi- 
cally. Some of them are very argillaceous, and a few arenaceous, while for 
variety 1 know of no district where it can be equalled. After carefully 
inspecting a number of these sections, I have found nineteen distinct 
characters, either chemically or physically, of which about twelve will be of 
value for pottery work. So pure are some of these clays as to require no 
elutriation,—as they are won from the cutting so they can go to the pug mill. 
Amongst them there is one terra cotta so rich in colour without any addition 
or treatment that this alone would be a valuable acquisition, and when we 
bear in mind the extent to which terra cotta ware is now coming into use, 
it will be seen that this is no fancy sketch. 
In the future we shall undoubtedly see extensive works located in this 
portion of the district for the use of these valuable clays, and the working of 
„these beds will be greatly facilitated by a small canal between the Manukau 
and Waitemata waters. 
Before leaving this part of my subject a few words upon a peculiar clay 
from Kaitaia may not be out of place. Having received some samples from 
the north of fine unctuous pipe-clay, I was informed by Mr. Kelly, of 
Mongonui, that they used a similar clay to make the roads with in that part 
of the district, and a large sample was forwarded to me, at my request, by 
Mr. Houston, who states that after spreading upon the roads at first, the 
horses stick fast, and have great difficulty in making their way, but that it 
soon hardens, and, after once becoming so, no amount of rain will cause it 
to puddle again. 
It has been found by later experience, however, not to have proved so 
valuable a material for road purposes as was expected. The surface be- 
coming abraded in the summer, suffers from the strong winds, which 
remove a good deal, thus rendering it necessary to frequently repair. On 
examination this material proves to be a diatomaceous earth, the diatoms 
being intermixed with very finely divided silica. The exceeding minuteness 
of these fossil diatoms is so great that under a power of 2,000 diameters 
