0.—9

36

■where they have not fallen, the binding-material has been so much removed that the shells are projecting, giving the whole rock an extraordinarily rough and coarse surface. This applies to the whole of the beds, but elsewhere secretion has gone on considerably, and the result is in places that the shelly character has been almost obliterated, and a sub-crystalline limestone is the result. The effects of this action can be seen in various stages, in even moderately small hand-specimens. On a larger scale the effects can be seen in the cave which penetrates the reef from east to west, where a stalactitic growth is in formation. The cave, seemingly, is the result of the enlargement of a blowhole, of which there are a number on the reef. Prom the Castle Eock to the end of the reef the beds have a synclinal arrangement. At the point of the reef they have a low dip to the southwest, with a strike of 45° west of north, while at the southern end, with the same strike prevailing, the beds dip north-west, and still at low angles. 1. Becent. The alluvial deposits call for but little comment. They consist chiefly of blown sands and morass, while in the Whakataki Creek bed occurs the ordinary detrital of a river. From the friable nature of the beds it traverses, the material has been reduced in size to small pebbles and sands. The material is chiefly the detritus of the shales and mudstones of the Lower division, and the glauconitic rocks of the Middle division, of the Upper Cretaceous system. The alluvial above is continued towards the southward to Castle Bay as blown sands. From the Otahome Creek to the south, aaolian deposits are in evidence, covering up the Cretaceous rocks for a length of two miles. Due to the low fall, and the smallness of the body of water carried by the Ngakauau, Otahome and other creeks, their alluvial occurs chiefly as morass, of which both creeks have a considerable area. Igneous Bocks. The instruction in part received was to search for and examine dykes and other igneous rocks. As mentioned in those instructions, Mr. A. McKay found in 1874, in the bed of the Ngakauau Creek, a specimen of Lucite. Although the Cretaceous rocks further to the south, at the Kaiwhata Eiver and at Waikikino, are penetrated by igneous intrusions, no such thing was anywhere observed in this area. The creek-beds of the Ngakauau particularly were examined, and the sections of the coast, all with the same result. The courses of the other streams in the district were also examined. As the area under survey is approximately twenty-five square miles, the same detailed examination could not be given to other parts that the rocks in the valley of the Ngakauau and the sections at its mouth received in the time taken. Moreover, the survey here dealt only with the eastern watershed, the summits of the Trooper Eange being the western limits. 30th June, 1899. William A. McKay.

EEPOET ON GEOLOGY OF EAST COAST FEOM THE KAIWHATA EIVEE TO GLENBUBN, EAST COAST OF WELLINGTON. By W. A. McKay, Assistant Geologist. Memorandum op Insteuctions foe W. A. McKay, Assistant Geologist. Me. McKay,— Wellington, 30th December, 1898. On finishing your work between Castle Point and the Lower Whareama Valley, you will forward a progress report embodying all the facts you have collected respecting the area you are now engaged on. The collections made should be boxed and despatched, addressed to the Undersecretary for Mines. They should be sent by sea from Castle Point, when opportunity offers, by some coastal steamer. Zou can arrange for the despatch of the collections, so that you may not be delayed in commencing further work south of the Whareama Eiver, and the Under-Secretary must be advised as to the time of the despatch of the specimens, so that they may be received on arrival at Wellington. These things done, or provided for, proceed to the Kaiwhata Eiver, and camp, at least for a time, at the point where the stream leaves the hills and the road to Flat Point crosses it. You can provide yourself with stores and what else you may require from stations in the Lower Whareama or from Flat Point Station. Your work in this part will be—First, an examination of the valley of the Kaiwhata Eiver, along which splendid sections of the rocks present are seen. Ample collections of the rocks must be made, the different formations discriminated, and your work placed on the maps while in the field. Sections must be sketched as, and when, seen, and ideal sections while yet the facts are fresh in your memory. The river must be followed up until reaching the Palaeozoic rocks of the Brocken Eange, constituting the water-parting between the Kaiwhata and the Upper Pahaoa. The rocks in the middle and lower valley of the Kaiwhata are probably of Cretaceous age, but fossils must be sought for in proof of this assumption. The rocks are of extreme interest, and consist of sandstones, shales, and limestones, associated with bodies of volcanic tuff and ash-beds, and numerous dykes of diorite, or syenite, and other hornblendic or augitic rocks. Second, having mastered the section along the river and the geology of the Kaiwhata Valley generally, continue the survey along the mountainous country in the direction of the Pahaoa Gorge, and approach your work from the coast-line at convenient and not too great distances from the last line of intersection. Third, search the older rocks for quartz-reefs and minerals of all kinds, and see also to the mineral contents of the younger formations. This piece of country is practically unexplored, and in it you have a rare opportunity. Make ample field-notes, and let these, revised, and in letter form, as progress reports, be sent as regularly as. can be to the tkider-Secretary. Alex. McKay.