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C—lo

Such being the state of things in the Kaimanawa Mountains, it is not now difficult to understand the occurrence of deposits of less depth and finer grain over parts of the country that lie more to the east and north-east. Recent. 1, b. Special Deposits of Pumice along the River-valleys. —These have already been referred to under heading of 2, a. Along the middle and lower courses of the rivers the pumiceous material often lodged at high flood-level, being of finer grain, is drifted away from the river-banks by the action of the wind, and in favourable situations has accumulated to deposits of considerable thickness. This is seen in the Ngaruroro Valley, at Kuripapanga, and at the crossing of the Taruarau River on the Inland Patea Road. The coarser pumice is carried farther by the current and lodged in the swamps of the low ground, towards the coast-line, or is carried out to sea. 1, a. Alluvial Deposits ; River-beds and River-terraces of Modern Date. —The principal deposit of this kind is the Ahuriri Plain, mainly built up of the waste of the Kaimanawa, Kaweka, and Ruahine Ranges, covered by silt from the Tertiary strata, and in the more swampy parts by pumice. Below the gorge, and before it enters the Ahuriri Plain, the Ngaruroro has deposited on the northern bank a high-level terrace plain of considerable extent, but elsewhere deposits of this age and description are not important. Conclusion. Though the principal object—the discovery of payable gold-deposits in the Kaimanawa Mountains—has not been attained, the expedition served the purpose of learning something of a considerable area of country the geology of which was not known, or had only been guessed at; and, notably, it has enabled a definite explanation of the occurrence of much of the pumice that covers the mountains and hilly country of a large part of northern Hawke's Bay district. It has also shown that the beds 3, b, in so far as they consist of pumiceous material brought from the west side of the mountain-chain, had other means of reaching into the eastern sea than by way of the Manawatu Gorge. These pumice-deposits, as forming marine strata, occur on the highlands of Inland Patea, associated with limestones, and it is clear that pumice drifting south from the Lake Taupo region could, by way of the Inland Patea depression, between the northern termination of the Ruahine and the commencement of the Kaimanawa Mountains, find its way to the eastern area, over which marine deposits partly formed of pumice sands are now found. Thus it will be seen that the Manawatu Gorge was not the only means of reaching by water the east side of the mountains during the Pliocene depression of the North Island, and in this respect the statements made in the report of 1899 have to be modified. The geology of the district is shown upon the map accompanying this report. 25th February, 1901. Alex. McKay.

REPORT ON THE PETROLEUM-BEARING ROCKS OF POVERTY BAY AND EAST CAPE DISTRICTS, AUCKLAND, NEW ZEALAND. By Alexander McKay, F.G.S., Government Geologist. Between the 11th March and the 16th April last, as directed, I made an examination of the Poverty Bay district with the object of determining the position and character of the rocks yielding petroleum, and the localities at which oil or gas escapes at the surface, and the following report embodies the results of my recent and previous visits to the district: — The Maoris were well acquainted with the occurrence of oil- and gas-springs over the region of the east coast of Auckland from East Cape to Mahia Peninsula ; but it was not till 1873 that the attention of Europeans was seriously attracted and attempts to obtain oil in quantity began to be made. In March, 1874, the district north of Poverty Bay was geologically examined by the Director of the Geological Survey, Sir James Hector, whom I accompanied to the oil-springs east of the source of Oil-spring Creek, in the Waipaoa Valley, thirty-five miles north of Gisborne, and also along the coast as far as the mouth of the Waiapu River, near East Cape.* At the time we visited the oil-springs thirty-five miles north of Gisborne a number of shallow holes had been dug, and the water in these and some natural pools was covered by a coating of oil, which was being collected from time to time. In the natural springs the oil was evidently coming up from some depth, but in the artificial holes it seemed to me that the oil was percolating from the sides of the excavations. After Sir James Hector left I continued in the district till the middle of May, and, during that time examiued most of the area over which indications of oil are to be found. Between 1874 and 1887 various companies were formed to prospect for oil, both in the Gisborne and Waiapu parts of the district, but were only partly successful in finding oil; and all of the companies have now ceased to operate. Shafts and shallow bores were put down where the oil showed at the surface a little east of the source of Oil-spring Creek. All of these failed, the shafts on account of the rapid accumulation of gas and the want of means for effective ventilation ; the bores from the unstable character of the ground in which they had been started. These difficulties might have been overcome, but eventually the South Pacific Company selected a bore-site some distance to the south-east of the oil-springs, in the valley of the

* See Geology of the District: Progress Reporc for the Years 1873-74 ; and reports relative to collections made in the East Cape district (" Geologioal Reports," 1873-74, pp. 116-164).