New analyses are given of the Glen More Ring-dyke. The basic end of the variation diagram is found to differ considerably from that of the Normal Magma Series. The magma variation is explained by gravitative sinking of augite and iron-ore (and plagioclase), the olivine of the Normal Series playing only a subordinate part. Various objections are brought forward to the explanation of the magmas by hybridization. The peculiar microscopic aspect of the intermediate rocks is tentatively attributed to pneumatolytic emanations from the lower reaches of the column. It is shown that a gradual transition from basic to acid already existed before the final consolidation of the magma took place.

During the past ten years a number of papers dealing with progressive regional metamorphism in the southern portion of New Zealand have been published. In the following pages a brief summary of the assemblages of minerals typical of the various metamorphic zones is given, but the writer's main object is to draw attention to certain mineralogical and structural peculiarities that appear to differ in some degree from what are usually regarded as the normal features of regional metamorphism in such classic areas as the Scottish Highlands and the Caledonian chain of Norway. The possibility that such departures from the normal may in some instances be connected with chemical peculiarities in the parent rock is suggested by such phenomena as the well-known general limitation of chloritoid, staurolite, and low-grade garnets to pelitic rocks of special chemical compositions. Other unusual features, especially when found to recur in widely separated regions, may well be governed by some particular combination of physical rather than chemical conditions.

The Glen Tilt Complex, one of the larger masses of the Newer Granites of the Central Highlands, is included in sheet 64 of the Geological Survey of Scotland. The greater part of this complex is a granite which is bounded on the south-west and southeast by an earlier series of intermediate and basic rocks. The granites described in this contribution are restricted to a small area at the south-eastern margin of the large granitic intrusion generally known as the Beinn Dearc granite. The smaller and independent intrusion of the Sron a ‘Chro’ granite and a number of smaller masses of granite associated with the marginal strip of diorites on the north-western side of Glen Tilt have also been examined. These small isolated areas appear to be contemporaneous with the intrusion of the main Beinn Dearc mass and have been intruded between the earlier diorites and the margin of the intrusion, a feature not uncommon in many of the other Scottish Newer Granites. A small independent mass of muscovite-biotite-granite intruded into quartz-mica-diorite occurs on Conlach Mhor. Although these rocks are completely isolated from both the biotite- and muscovite-biotite-granites of the main Beinn Dearc intrusion their essential similarity with the latter leaves no reasonable doubt of their common origin.