a—2b

1930. NEW ZEALAND

REEFTON COALFIELD (REPORT ON THE), by Gordon J. Williams, M.Sc., F.G.S., A.O.S.M.

Laid on the Table of the House by Leave.

CONTENTS. Page (1) Introduction .. .. .. .. .. .. .. .. .. ..2 Output of coalfield —Reasons for limited production —Scope and object of survey field-work —Previous geological work. (2) Stratigkaphic Succession in Inanqahua Valley .. .. .. .. .. .. 3 (3) The Coal-measures .. .. .. .. .. .. .. .. .. .. 3 (a) Occurrence. —Extent of field —Relationship to neighbouring formations. (b) Description of Coal-seams. —The three main scams of coal —Existence of " No. 1 " seam—Description of Nos. 2, 3, and 4 seams. (c) Formation of Goal-measures. —Deposition in growing depression —Overlap on margin of depression— Extension of coal-measures longitudinally and transversely. (4) The Waitahu Marine Beds .. .. .. .. .. .. .. .. .. 7 Variation in character from south to north —Traces of coal —Nature of unconformity above coal-measures. (5) Structure of Coalfield .. .. .. .. .. .. .. .. 8 Behaviour of thin bedded series of sediments under strain—Application of principle to Reefton field — Two typos of fault —Relationship between faulting and main synclinal structure. (6) Economic Problems .. .. .. .. .. .. .. .. .. .. 9 (a) Extension of Coal-measures beneath Inangahua Valley. —Blind outcrops—Possibility of coal pinching out. (6) Nature of Faulting which may be encountered. —Probability of impenetrable faults —Suggestions for penetrating faults. (c) The Flattening of the Measures in Depth. —Local belief considered unlikely—Average decrease in inclination —Value of observations on Waitahu Cliff. (7) Amount of Coal available .. .. .. .. .. .. .. .. ..11 Computed amount of coal available in each seam on the various leases. (8) Definition of Terms .. .. .. .. .. .. .. .. .. 12 Syncline and anticline—Monoclinal flexure —Graben —Conformity, unconformity, and blended unconformity.

I—C. 2b.