H.—34,

Structure. The Greenland rocks, besides being folded, have been subject to thrusting movements. This is demonstrated by the asymmetry and overturning of folds and by the presence of low-angle faultplanes and shears. Eastward-dipping flanks of folds, except near the sheared and complicated crests and troughs, are usually little disturbed and moderate in slope, whereas west-dippmg limbs tend to be steep. In places—for example, in the Snowy River near the Waiuta battery and m Italian and Raglan creeks near Capleston—the folds are overturned towards the west. In the Snowy River and at Big River Mine severe crumpling and shearing of the quartzites near the boundary of the granite to the east points clearly to thrusting from the east. Normal faults, which also are recognized m the area, may have been produced during periods of tension.

Blackwater and Big River Groups of Mines and Associated Structures.

A major anticlinical structure was traced north from the Snowy River at Waiuta towards Merriiigs This fold was recognized in Blackwater Mine, in Blackwater Stream, in Big River at the junction with Sunderland Creek, and northwards. Its crest is complicated at Waiuta, and a small anticline and syncline are superimposed upon it. Northwards it possibly joins up with an anticline mapped at Merrijigs. Steepening and overturning of the west flank is noticeable. East from the axis the east-dipping flank persists, with fair regularity to near the St. George Stream. _ Here the structure is complicated and a syncline is developed on the long east-dipping limb, its trough traceable through to the Big River Mine, which is located within the sheared axial belt. I his syncline was also mapped in Golden Lead Creek, but could not be followed farther north owing to a cover of younger rock. Southward from the Snowy River gravels obscure the structure. The syncline extending from Crushington northwards to the Waitahu River and carrying along and close to its sheared axis the Crushington-Xnglewood group of lodes was traced farther north through the Boatman's mining area to Raglan Creek, beyond which it disappears beneath gravels. THE W.ARY University v, Canterbury CHRiSTCHURCH, Ni

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