H.—34.

South-eastern Area. —The Brunner coal-measures have been studied on the western slopes of Mount Davy in the Seven-mile and Coal Creek valleys. The outcrops of different members of the Paparoa measures were traced in the Seven-mile valley for correlation purposes, for information about faults, and to assist in selecting sites for deep drilling. The detailed work is largely complete except for the area west of Spring Creek and immediately north of the Seven-mile Stream. The Survey has advised on geological matters concerning the Liverpool State Colliery and several co-operative mines, reports and plans having been prepared in this connection. North-western Area.—With consideration given to the geological aspect of mining difficulties, detailed correlation of seams and the elucidation of faulting continued in this area. During the early part of this season the mapping of the south side of the lower Ten-mile valley was completed and attention has since been concentrated on Griffiths, Nine-mile, and Kiwi streams. The main traverses along creeks and ridges having been completed, the detailed mapping of intervening areas is in progress. Special attention is being directed to faulting and structural problems in the vicinity of the Strongman State Mine. Brunner Area.—Geological work has recently been commenced in this area as a preliminary to geophysical experiments aimed at the elucidation of the fault system. Stbuctuke. South-eastern Area. The Seven-mile valley, Coal Creek, and the south-western spurs of Mount Davy afford a generalized section across the coalfield, showing two north-north-east-striking asymmetrical anticlines separated by a complex strongly faulted depressed zone. To the east of these structures a comparatively undisturbed dip-slope capped by Brunner beds extends to the crest of the Mount Davy - Brunner ridge. The southern portion dips evenly westward, but northward the strikes swing in a broad arc so that on Mount Davy and in Davy Creek the dips are to the south-west; a broad intensely faulted area with widespread deep talus separates the northern end of the structure from an anticlinal structure to the west. All these structural units are more or less disturbed by normal and compressional faults, the former with displacements of up to several hundred feet. The axis of the western anticline crosses the Seven-mile Stream at Moody Creek Mine, passing northward along the slopes west of Spring Creek ; but southward it has been mapped only as far as Coal Creek, passing close by Trig. A. Disrupting the broad western flank the Dunollie Fault has a downthrow to the west of up to 150 ft. Other faults with displacements of from 12 ft. to about 50 ft. are known, having been encountered in the old Point Elizabeth State Colliery and neighbouring co-operative mines. From the Moody Creek Mine a fault appears, increases to about 12 ft. of throw, and dies out within a distance of about 3 chains. All the more important faults strike between north and north-east. On the steep east-dipping limb of the fold, close-spaced faults break up the terrain into narrow blocks such as that in which Baddeley and Party worked an exceedingly steep seam. The old east-dip workings of the Moody Creek Mine are similarly situated on the steep east limb. The synclinal area to the east is so disturbed that it is better to regard it as a complex depressed and faulted belt. From Coal Creek it crosses the divide into the Seven-mile valley near Bend Creek, thence up Spring Creek and over the saddle into the watershed of Bishop Creek. This fault has been referred to in previous reports as the Spring Creek fault-zone. Within the disturbed zone, but apparently free from serious faulting, one west-dipping block extends eastward from the Runanga water-supply tunnel for about 16 chains. Its eastern margin is a sharp flexure producing steep north-easterly dips. A short distance farther to the east, there is a fault, which, although obscure, undoubtedly has a considerable upthrow to the east, and beyond which lies another west-dipping block about 3 chains wide. These are the easternmost blocks containing workable members of the Point Elizabeth coal-measures —that is, the uppermost Paparoa seams—and are to be developed by Currie and party from the Seven-mile side. The area of workable coal is restricted by the faults and by the barrier required to be left to protect the waterworks. In this vicinity the trend of structures, including faults, has swung west of the meridian. Eastward from the depressed zone is the west flank of the adjacent anticline broken by faults, mostly normal, of the dominant north-east system. The crest of this structure can be followed from Batty Creek northwards across Coal Creek, the Seven-mile Stream, and on the intervening ridges. Thence northward it parallels the meridional reach of the Seven-mile Stream. It maintains its identity as a generalized structure through the Liverpool State Mine and beyond to the northern margin of the coal-measures in Otto Creek, although considerable complexity appears in this northern area. The Denston Fault, which bounds the Binn's Section of the Liverpool Mine to the west, is probably identical with a fault west of Hunter and party Seven-mile workings, but it has not been detected south of the Seven-mile Stream. The area west of the Denston Fault appears to be too broken by close-spaced faults and too uncertain as regards coal content to be attractive to co-operative miners. The crest of the eastern anticline is disturbed by a small compressional fault at Tyson Creek ; this was investigated in detail during the selection of a site for a deep borehole. One of a group of north-east-striking faults east of the structural crest crosses Williams and party lease, but from surface observations in Coal Creek and on cliffs above the mine it is anticipated that this fault, if not entirely absent, will be of small throw in the new workings. In addition to the main north-east fault system, an east-west set of fractures are chiefly known from the mine workings, but appear to be generally of small displacement. This field generalization was applied to faulting problems in Williams and party Mine, the party being persuaded to prospect through an east-west fault, thereby proving it to have displaced the seam by an amount little more than the height of the coal.

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