long, lying at any angle to the schistosity. It is of the dark olivine green type with but little brownish tinge, and is therefore rich in ferrous oxide (cf. Hutton, 1938). A little chlorite, actinolite and pyrites is present. In (4856) actinolite is abundant, and the brownish stilpnomelane still more so, while clinozoisite occurs only in small grains in the thin turbid sericitic streaks. Both coloured minerals are elongated in the general direction of schistosity. Quartz-stilpnomelane-spessartite-schist. This has so far been obtained only at Locality 17 from Mount Blockade, at the head of the Forgotten River near the transition between the Chl. 3 and Chl. 4 sub-zones. It (4745) is a dark glossy brown slightly foliated schist. The quartz grains (about 0.1 mm. in average diameter) are aggregated into laminae about 0.5 mm. thick, alternating with thinner layers composed chiefly of stilpnomelane flakes about 0.5 mm. long, lying almost parallel to the schistosity. Flakes of this mineral also occur in subradiating aggregates or singly, lying obliquely across the quartz laminae. Associated with the dark layers are streaked aggregates of innumerable minute (0.01 mm.), almost colourless, idioblastic garnets, which are also scattered sparingly through the quartz layers. Dr. Hutton has kindly examined this slide and remarks (priv. com.) that it is a normal type comparable with rocks found in the Chl. 3 and Chl. 4 sub-zones in the Lake Wakatipu region, and may be compared with one (3202) from Staircase Creek near Kingston which he has illustrated (Hutton, 1938, p. 175, fig. 3b). The tiny garnets forming strings and dense clusters are a common feature in schists such as this; they contain very high MnO and may correctly be called spessartite. The stilpnomelane has an olive-green to olivine-brown colour, and therefore must contain appreciable FeO, and as spessartite is abundant, the parsettensite molecule may be present in considerable amount in the stilpnomelane mineral. He agrees that it is probable that the few small (0.015 mm.) idiomorphic almost colourless doubly terminated prisms may well be the almost colourless tourmaline elbaite. Some General Considerations. Certain major features of tectonic interest are suggested, not only by the distribution and characters of the various grades of metamorphic rocks, but by their relation to the line of ultrabasic intrusion to which attention will be first directed. The elongation of the intrusive masses of ultrabasic and basic igneous rocks along the general strike of the Southern Alps has been generally recognised, and was summarised by one of us (Benson, 1926), but as a result of the present mapping, and more particularly of the work of C. O. Hutton (1937), who has traced the extension of these rocks for sixty miles further to the south, it is now possible to recognise that it swings in a westerly convex arc a hundred miles in length. This long arcuate line of intrusions exemplifies excellently Suess's dictum (1909) that such intrusive masses “form sills in dislocated mountains