H.—34.

Armstrong Fault. —Crossing the Ten-mile Stream about 15 chains downstream from Doherty Creek junction, this fault cuts off Armstrong and party workings to the east. It is seen in the Nine-mile Stream and the cliffs above and to the north of the State Mine workings. In the State Mine workings there are two faults which intersect the main drive at respectively 21 chains and 23 chains from the entrance, and these probably represent a bifurcation of the Armstrong Fault. In the Armstrong and party area this fault has a downthrow of about 300 ft. to the west, but it dies out southward before reaching Kiwi Creek, beyond which the west branch is represented by a steep roll and the east by a small, gentle syncline. Doherty Fault. —This fault, which dips northwestward at about 60°, crosses Ten-mile Stream 2J chains above Doherty Creek junction, where the lower mudstone is downfaulted westward some 600 ft. against the Paparoa Basal Conglomerate. Farther north, where it displaces Bishop Creek and Strongman seams, the throw is difficult to estimate on account of another fault which appears to be a fracture diverging from it, striking sub-parallel on its eastern side. This split, the Point C Fault, is thought to have a westward downthrow of about 140 ft. Thence southwestward Doherty Fault crosses Nine-mile Stream about 7 chains downstream from Borehole No. 6, where its throw is considerably less than 600 ft. In this vicinity nearby parallel fractures probably take up the displacement of the fault. It is seen in the cliffs on the south side of Nine-mile Stream, and it traverses the State Mine workings as a steep roll displacing the strata about 20 ft. downward to the west. Immediately east of this point a small parallel fault, or a split from the dying-out Doherty Fault, downthrows the strata about 12 ft. to the west. The Doherty Fault has not been found to cross Kiwi Creek. Smaller Faults of the North-east-striking System.—There are several smaller faults belonging to this system which have been traced for short distances only. Among these is the fault that cuts off the Kaye and party seam to the west with a westward downthrow of about 100 ft., and the small fault about 6 chains north-west from Trig. C that strikes towards the headwaters of Kiwi Creek and has a downthrow to the west of about 20 ft. Stratigraphy. As explained in earlier annual reports, the absence of fossils necessitates lithologic correlations. At this stage of the work it is not yet possible to give a final account of the succession over the whole area, as several important matters are still in doubt. There is no complete section of the coal-measures west of the Paparoa Divide ; the upper part has been established in the south-eastern area and the lower part in the north-western area, and correlation between the two is difficult. The following stratigraphic section is based on field observations of the most complete sections and bore-hole data ; where information is lacking inferences have been made from cross-sections : — Sotjth-eastebn Section. North-western Section. Calcareous mudstone (Kaiata beds) .. .. .. Calcareous mudstone. Calcareous sandstone (Island Sandstone) .. .. .. Calcareous sandstone. Coal-measures (Brunner, James) .. .. •• James coal-seam. Conglomerates (Brunner Conglomerates) .. .. .. Conglomerates. Unconformity. V nconformity. Coal-measures (Point Elizabeth seams) .. .. .. Sandstones and coaly sections. ♦Massive mudstone .. .. .. ■ ■ • • *Massive mudstone. Coal-measures (Moody Creek, Binn's, Kimbell, &c., seams) .. Coal measures (Strongman and Bishop Creek seams). *Massivo mudstone .. .. .. • • • • Massive mudstone. Coal-measures (Morgan seam) .. .. .. .. Thin coal-measures. Conglomerates (Basal Paparoa). Unconformity. Greywaeke, argiilite (Greenland Series). •It is uncertain which of the mudstones in the south-eastern section is to be correlated with the upper massive mudstone of the north-western section. The unconformable contact at the base of the Brunner Conglomerate that has been observed in the Seven-mile - Dunollie area is also to be seen just below Trig. C to the east, and less plainly on the ridge east of Trig. WP. Another break in the succession is suspected at the base of the series of sandstones and conglomerates that underlies the lower Strongman State seam (Armstrong and party lower seam), and overlie the Bishop Creek seam. Very little can be said about this probable break, which is deduced from the different thicknesses of the stratigraphic column in measured sections, from the suggestion that the smaller faults in the underlying strata do not displace the upper beds, and from the fact that the conglomerates contain water-worn coal pebbles. As indicated above, correlation of the stratigraphic positions of the two massive mudstones in the south-eastern area with those of the north-western area is uncertain. Consequently there is some doubt as to the correlation of the Dunollie-Rewanui seams with the Nine-mile - Ten-mile seams. It is to be hoped that this matter will be cleared up by the deep bore-hole that it is proposed to drill at the Tyson Creek - Seven-mile junction, and in the course of field-work between Spring Creek and the Nine-mile. Samples of the several mudstones have been forwarded to the Petrologist in the hope that heavy mineral determinations may help in the correlations.

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