Art. XLIII.—Petrological Notes on Rock Specimens collected in South Victoria Land.

By Richard Hansford Worth, Assoc.M.Inst.C.E., F.G.S.
Comunicated by T. V. Hodgson, F.L.S.

The following rocks are either not dealt with in the official report, except perhaps in some instances macroscopically, or show variations in the slides now prepared and examined. The details as to locality and general accounts of occurrences are furnished by Mr. Hodgson.

Castle Rock. — 1, camptonite in so far as it contains amygdaloids of analcime.

Termination Rock.—3, trachyte.

Sultan's Head.—3, pumice.

Erebus.—1, trachydolerite; 3, diorite; 4, felsite.

Turtle Island.—2, trachyte; 5, augite nodule without olivine.

Inaccessible Island.—1, augite-andesite; 2, phonolitic trachyte, undescribed in detail; 3, trachyte.

Black Island.—1, diorite; 3, quartz-felsite; 4, sandstone; 5, quaitzite; 6, camptonite; 7, augite-diorite; 8, camptonite; 9, micro-pegmatite; 11, augite-diorite; 13, 14, altered sedimentary, here described in detail; 16.

Brown Island.—2, basalt; 3, andesite; 4, basalt.

Western Mountains.—1, mica-schist; 2, dioritic lamprophyre; 6, tuff.

Granite Harbour.—1, felsite; 2, quartz-diorite; 5, quartz-mica-diorite.

In some instances a description of the rock has been given, but no specific or varietal name applied. Such omission is probably unimportant in any event, and must be taken as indicating that analysis as well as microscopic examination might be desired.

Observation Hill

Dark-grey trachytic rock, with phenocrysts of augite up to 3 mm. and of olivine up to 4 mm. in length. It is slightly vesicular. Groundmass microlites of brown augite, of olivine-feldspar in lath shape, and magnetite. Larger augites are of a somewhat lighter shade, and show zonal structure between crossed nicols. Larger olivines are numerous, and very uniformly distributed. Fibrous isotropic patches occur, which may be analcime. Beyond a few larger laths, the porphyritic feldspar is confined to one crystal in which a band of inclusions marks out a rhomb.

Castle Rock.

Castle Rock is a mass of reddish breccia, and rises to a height of about 400 ft. above the general level of the Ridgeway. It gives one the impression of being the solidified pipe of a vanished volcano. Between the rock and the shore, but at a considerably lower altitude, were several small cones extending over an area something like 300 yards towards the ship. All the specimens taken came from one or other of these cones, and were obviously in situ, though taken from detached fragments.

Castle Rock, 1.—Dark-grey, minutely granular rock. Enstatite, brown mica, feldspar in broad laths and irregular patches, uniformly clouded. Camptonite. From small cone below Castle Rock, nearest to ship, in situ.

Castle Rock, 2.—Black basalt, in part highly vesicular, in part compact. No visible olivine. This rock, with Castle Rock, is typical of this area; both are from the same cone.

Castle Rock, 3.—Very dark-grey rock, slightly vesicular, with zeolitie amygdaloids, minutely crystalline texture. Groundmass, feldspar laths, minute pale-brown augite, olivine, and magnetite. Larger forms of olivine and augite, frequently with good outline. The zeolite filling the vesicles is

isotropic, probably analcime. Basalt. From small cone within 200 yards of Castle Rock, south of and below same.

Castle Rock, 4.—Black basalt. Prominent crystals of black augite and pale-green olivine. There is a sharply denfined inclusion of granular augite and olivine, with no trace of any transitional material, between this and the basalt; greatest dimension of inclusion as shown in specimen, 45 mm. Another specimen shows an inclusion, equally well defined, which is practically all olivine, there being only one visible fragment of augite. A section of the augite-olivine inclusion shows coarse-grained olivine-augite rock with ophitic structure. The augite pale green with a shade of pink, non-pleochroic. The merest beginnings of schiller structure are visible in places. Below Castle Rock, nearest to the rock.

Second Knoll.

Black Vesicular Basalt.—This was one of the less-prominent landmarks, and consisted of a cone of angular lumps of black vesicular basalt of vitreous appearance. From this a ridge of snow extended northwards for some 200 or 300 yards. Whether this was a compacted drift ridge or merely a bank of basalt covered with snow it is impossible to say.

Termination Rock.

Termination Rock is officially known as Hutton Cliffs. The name was given by Mr. Hodgson for his own convenience, as the exposure was the most distant one from the ship, and therefore the last on the Ridge-way. No. 1 was taken from the base of the cliff, which is some 200 ft. high, and sheer.

Termination Rock, 1 (Hutton Cliffs).—Compact, olive-green mottled with black. Many of the black included fragments are obviously amygdaloidal, the vesicles being filled with white zeolite; spots of this mineral also occur in the green part. A volcanic agglomerate. Fragments of green, black, and brown glassy highly vesicular rocks, all of which contain olivine crystals. Some of the black fragments are amygdaloidal, the vesicles being filled with a dull dusty-looking substance of finely fibrous structure, white by reflected light. This same substance also occurs at intervals throughout the slide, between the constituent fragments. One or two small black patches show numerous lath-shaped feldspars. Brown augite is rare, and present in small forms only. The glass in this rock is now represented by alteration-products.

Apparently akin to the tuffs from “Bare Rocks” mentioned on page 110 of the official report.

Termination Rock, 2 (summit).—Some small specimens of black vesicular basalt.

Termination Rock, 3 (summit).—A dark-grey slabby rock, with slight green shade; shows a little tabular feldspar. Microlitic groundmass very ill-defined feldspars, small irregular prisms and pairs of very pale-green augite, sphene, magnetite. The larger constituents are feldspars, chiefly in elongated forms, but at places stouter; nearly all ill-bounded, and many so crowded with microlites that it is only between crossed nicols that they can be distinguished. There are a few augites slightly larger than the general run, but these are rendered practically opaque by minute magnetite. Trachyte.

Sultan'S Head.

Sultan's Head, 1.—Olive-brown tuff, rather soft. A typical palagonite tuff; the grains are subangular, and a few present spheroidal structure. In places a vesicular form in the original material is evidenced. A little calcite here and there, and much colourless cementing-material, which is not quite isotropic. A variety of the basalt tuff from Sultan's Head described on page 109 of the official report.

Sultan's Head, 2.—Specimen showing passage of olive - brown tuff (Sultan's Head, 1) into volcanic agglomerate with this material as a base and considerable included fragments of dark basalts.

Sultan's Head, 3.—Small specimens of grey pumiceous rock. The interiors of the gas-cavities highly glazed. A highly vesicular rock, pale-grey base not quite isotropic. Fragments of both quartz and feldspar, the former with small fluid inclusions, none of the feldspar twinned. A little granular magnetite. Pumice. It is not certain that this occurs-here in situ.

Mount Erebus.

The base of this mountain to the west of the Ridgeway seemed to be composed almost entirely of kenyte. The larger exposures of Skuary Point, Cape Barne, and Cape Royds had other rocks in addition, the last-named with a copious sprinkling of blocks of granite. No. 1 specimen was taken from the sea ice immediately below a small exposure some few feet above sea-level, from which it had obviously fallen. This exposure was on the side of Mount Erebus, but only a few yards from the origin of the Ridgeway.

Erebus, 1.—Reddish-brown rock, compact base. Numerous tabular feldspars, water-white, with visible inclusions of groundmass. The planes of all these feldspars are approximately parallel, and thus on one surface they give lath-shaped sections, averaging about 12 mm. by 1·5 mm. The rock is also slaggy, and contains gas-cavities flattened and elongated parallel to the planes of the feldspars. While quite fresh it is thus very friable. The groundmass brown, apparently glassy, with brown and black dusty inclusions; contains numerous lath-shaped feldspars. In some cases these are invaded along the centre from either end by black dusty material, which shows somewhat elongated forms under high power. The larger crystals of anorthoclase contain numerous inclusions of groundmass, arranged in zonal fashion, and the crystals show between crossed nicols slight local differences of tint which mark out zones exactly corresponding to the inclusions. The olivine crystals are pale green, and usually accomplish clear crystal outline over rather more than one-half of their circumference, being invaded elsewhere by prolongation of the groundmass, severed inclusions of which are also common. Nepheline is rather prominent in some parts of the slides, and in one place is associated with an olivine crystal. Trachydolerite, akin to kenyte.

Erebus, 2.—A compact grey rock of close texture, with slight tendency to cleave in flakes. Numerous tabular feldspars, mainly but not entirely in parallel planes. These give lath-shaped sections up to 25 mm. in length, and are 2 mm. in breadth. A comparatively pale ground, considerably darkened, however, by fine granular magnetite. Much looks like a brown glass, but no part is actually isotropic. There are numerous small feldspar laths. The larger feldspars are striated with alternate narrow and wide bands; the largest show zonal structure between crossed nicols, and small

olivine inclusions as well as slight inclusions of groundmass. Some small and well-formed nepheline, occasionally with central inclusions of ground-mass. Pink-brown augites; small forms are rare. A fair amount of olivine; small forms are again rare. Some large grains and crystals of magnetite. Two cracks in the rock have been recemented with a clear colourless mineral of very low double refraction. Trachydolerite. Specimen taken from the end of the jetty in situ.

Erebus, 3.—Coarse-grained granitic texture, with tendency to banded structure. The larger feldspars flesh-coloured, the smaller semi-opaque white. Quartz clear. Much black mica. Feldspar slightly clouded, but in places quite clear, practically all striated; all contains apatite. Patches of micro-pegmatite. There are large areas of quartz, which show fairly numerous fluid inclusions with bubbles. A fair amount of dark mica in brown and green shades. Quartz-diorite. From Cape Royds, not in situ.

Erebus, 4.—Felsitic texture; granular crystalline; general shade light indian-red; some feldspars, all quite small, are a brighter pink. Micropegmatite, with patches of clouded red feldspar in tesselated form, and other areas of clear colourless feldspar in similar form; striation not infrequent, but somewhat indistinct. One feldspar is clouded in centre, with clear outer zone, surrounded by micro-pegmatite. A somewhat similar case occurs where the centre is of a pale green-grey and polarizes differently from margin, although extinguishing with it. Hornblende in blades and irregular forms, olive-brown in parts but mainly green, is scattered rather sparsely through the slide. The larger grains of quartz are not prominent, and contain a few very small fluid inclusions with bubbles. From Cape Royds, not in situ.

These last two specimens are samples of the numerous blocks of granitic material which lie here and appear to present great variety.

Turtle Island.

Turtle Island was a small pyramidal islet some eight miles from the ship, and the object of rather frequent excursions. It is about a couple of hundred yards long and little more than half that in diameter, perhaps 60 ft. high. On its eastern side were considerable pressure-ridges on the sea ice. At the eastern base the rocks were compact, weathered to simulate stratification, and appeared to be the ordinary olivine basalts of the district, but here the olivine crystals were very large and conspicuous. The general surface of the islet consisted of very fine rubble, with occasional boulders of kenyte and other volcanic rocks, the crystals from which sparkled in the sun like diamonds, and were rendered conspicuous for a considerable distance.

Turtle Island, 1.—Two specimens, one with a black compact base and very elongated rhombs of feldspar, practically lath-shaped in cross-section; the other brown-black, rougher and more slaggy base, with well-developed rhombs of feldspar. The first shows parallel structure, the second does not. Trachydolerite and kenyte. These specimens were from houlders.

Turtle Island, 2.—Dark-grey, compact trachytic, with large vesicles, up to 13 mm. diameter. Cleaves easily in slabs of irregular form from 5 mm. to 10 mm. thick. Groundmass light purple-brown augite and plagioclase feldspar in wisps and rods, with a little olivine and considerable quantity of magnetite. The sole porphyritic constituent is feldspar in very irregular forms. Trachyte.

Turtle Island, 3.—Granular, somewhat friable, black and very light grey; in a fresher piece the light crystals are more amber-coloured. One specimen shows that this rock occurs as nodules in a black basalt of vesicular character. In some pieces the olivine and augite are clearly recognizable as such in the hand-specimens. There are small specimens in which olivine is present to the practical exclusion of all other minerals. Nodules from basalt.

Turtle Island, 5.—A very heavy black friable granular rock with iridescent play of colour on the grains represents apparently a nodule from basalt in which the augite is present to the practical exclusion of all other minerals. Rich-brown augite (pseudo-hypersthene) in large ophitic plates. No recognizable pleochroism. The cracks stained a very dark brown, almost black. Numerous inclusions, very dark brown, lying along two directions coincident with the cleavage. Many of these inclusions are mere rods, others are lath-shaped, some few are broader plates. They exhibit no pleochroism, and appear to be isotropic.

Turtle Island, 6.—A small weathered stone, grey and buff. Base apparently feldspar, colourless, giving aggregate polarization in low tints, and showing an occasional rod form. Granular magnetite scattered uniformly throughout the slide. There is much of a golden-brown mineral in platy and sometimes rough prismatic form, which is bright orange-yellow by reflected light, shows no pleochroism, fairly high double refraction, and straight extinction in sections approaching the rectangular; this occurs in very minute forms.

Inaccessible Island.

The outermost of the Dellbridge Islands, so called because it was difficult to make the ascent. The northern side consisted largely of black basalt, weathered to simulate stratification up to a height of nearly 20 ft. Near the western end was a large scree of very fine rubble. The rocks were much confused at the eastern end, where all the specimens were obtained, and apparently dipped to the south.

Inaccessible Island, 1.—Medium grey, trachytic texture. A very few visible augites. White spots of intersecting feldspar crystals, in many cases in small druses. Groundmass pale grey, consists of a felted mass of minute fibres, with some magnetite, largely in very minute forms, and numerous rather irregular prisms of very pale-green augite. Very numerous feldspar laths, rather stout in section, for the more part simply twinned. The symmetrical extinctions are ± 20°, which suggest andesine. The slide also shows glomero-porphyritic structure, with aggregates of twinned feldspar free from interstitial matter; in one of these aggregates occurs a crystal with very closely repeated twinning, but elsewhere all are simple twins. One larger porphyritic feldspar occurs, with numerous inclusions of augite and magnetite. An occasional pale-green porphyritic augite, some with good crystal form, some much rounded, yet others entirely clouded with magnetite. Augite-andesite.

Inaccessible Island, 2.—Yellowish-grey trachyte, minutely open-textured. A pale yellow-brown ground of varying depth of tint, of very feeble double refraction, and containing both magnetite and sphene in minute forms, with rarely a small grey-green prism microlite which is apparently augite. Numerous well-terminated feldspar laths, and some few rather larger and stouter forms. Around the larger of these the lath feldspars show flow

structure. The rock appears vesicular, with the vesicles sometimes completely, sometimes only partially, infilled with a zeolite, which is probably analcime. Many of these zeolitic areas have, however, the distinct appearance of being pseudomorphs after some previously existing mineral, and hexagonal sections for this latter are fairly clearly indicated here and there, with residual patches of unaltered mineral which may well be nepheline. The extremely small percentage of augite is noteworthy. Treatment of a section with HCl followed by fuchsin produces differential staining. The groundmass becomes bright red, the feldspars remain water-white, and the zeolite areas take a violet shade. It then becomes clear that these latter are in many cases very certainly replacements of a mineral of hexagonal form. The straining of the groundmass also throws into relief numerous thread-like feldspars of a smaller order than the lath shapes, which alone are clearly discernible in the unstained specimen. The HCl which has been in contact with this rock is stained with iron, and yields on evaporation deliquescent crystalloids with cubes of sodium-chloride. The other chlorides apparently include that of aluminium. Phonolitic trachyte (altered). Apparently official specimen 803.

Inaccessible Island, 3.—Purple-brown trachytic texture, rather compact. The ground a rich-brown glass, with some magnetite. Very numerous lath-shaped feldspars fairly well terminated, and frequently showing a line of inclusions of groundmass down the centre. There are also smaller much-attenuated feldspars. The laths as a whole have one general direction. Larger feldspars, rectangular and rhomboidal, occur; these are mainly associated in groups of two or three, in contact with each other and partly intergrown, and show considerable glass inclusions, but only in one case polysynthetic twinning. No nepheline or zeolite is discoverable, but the rock is in many respects much like Inaccessible Island, 2. Trachyte, probably phonolitic. Apparently official specimen 802.

Black Island.

The first camp here was pitched about the middle of the eastern side of the island, not far from where the party landed. The specimens Nos. 2 to 7, 9, 10, and 14 were all taken from a “rubble-heap” a few yards from the tent. This so-called heap was an area some 20 yards by 3 yards, and none of the specimens were in situ.

Black Island, 1.—Dioritic texture, dark brown and practically white crystals. Brown augite, ophitic, diallagic in parts. The margins frequently darkened, sometimes with the development of a rich-brown pleochroic mineral. A few crystals are partially altered to uralite. Much feldspar, apparently all labradorite. Considerable areas of micro-pegmatite, in which the feldspar is always clouded. A sprinkling of ilmenite and some apatite. Quartz-augite-diorite. From half-way up peak of island, not in situ.

Black Island, 2.—Coarse-grained granite, pink feldspars, apparently precisely like Erebus, 3.

Black Island, 3.—Very fine-grained pale-grey rock, slightly mottled. Much white mica in minute brightly sparkling form. Groundmass microfelsitic, with minute sericitic mica. A few scattered grains of magnetite. Scattered blades and grains of olive-green hornblende, some of which shows striking pleochroism from olive to vivid blue-green. The porphyritic constituents are patches of much-clouded white feldspar, and quartz in sharply

Black Island, 10—Black basaltic rock, with olivine freely developed. Groundmass holocrystalline, consists of lath-shaped feldspars, brown augite, olivine, magnetite, and sphene. Feldspar also occurs in larger form, with rounded outline, and showing between crossed nicols a few very narrow bands widely spaced. Olivine inclusions in this feldspar. A few larger forms of pale-brown augite with rounded outline. Frequent larger olivines, mainly idiomorphic, but some with corroded outline. Trachydolerite.

Black Island, 11.—Weathered pebble. Rough-textured fine diorite in structure. Colour brownish-grey. Large plates of augite, in parts markedly diallagic. The more normal mineral has a distinct pleochroism from pale bluish-grey to pale pink. Here and there is slight decomposition, with development of serpentine. There is a very little brown mica, with strong pleochroism. Between the augite areas is a matwork of dear feldspars in moderately stout forms, apparently labradorite. Slight decomposition occurs here and there. Ilmenite and apatite are also present. Augitediorite.

Black Island, 12.—Very light warm buff, with greener shades locally. Trachytic texture. Ill-bounded feldspars, mainly lath-shaped, but some of stouter section, in a groundmass of minute feldspar mosaic. A fair quantity of aegirine-augite, pleochroism yellow-brown-green to blue-olive-green, in small prismatic forms and grains, for the more part ill-bounded. Possibly a little apatite. Under the ⅙-inch objective minute hexagonal and square forms of a clear mineral are visible. When the section is treated with hydrochloric acid, well washed, and stained with fuchsin it takes the dye locally where these hexagons and squares occur, and shows them marked out by the cleavage-cracks in larger forms of a mineral which is almost certainly nepheline. Phonolitic trachyte. From south-west corner of island; occurs in situ. This is 610 of official report, but there reported in error as from south-east of island.

Black Island, 13.—Volcanic agglomerate. Greenish base with black nodules, evidently basaltic. From north end of island. Described on page 139 of official report.

Black Island, 14.—Dark-grey rock, almost black. Tendency to conchoidal cleavage. Very close grain. Micro-crystalline quartz and reddish-brown mica are the prominent constituents. There is a distinctly parallel structure throughout the slide, but no banding. A fair amount of magnetite in irregular patches. An altered sedimentary rock from a contact zone. Apparently official specimen 525, page 135.

Black Island, 15.—Very dark-grey compact rock. Possibly a very little olivine. Groundmass microlitic. Consists of feldspar laths all conforming to one general direction, sphene, magnetite, and augite. In this occur larger water-clear feldspars, some striated, some zoned, many in associated intergrown crystals. A few porphyritic very pale-brown augites, and sphene in larger forms than in the general ground. From top of north peak of island, practically in situ.

Black Island, 16.—Slaggy vesicular lava, exterior with green tints, fracture red and black. Very closely resembles Brown Island, 4. From top of north peak of island, in situ.

Brown Island.

Brown Island, 1.—A very pale-grey slightly greenish trachyte. Compact and hard, weathered surface hard also. A few dark acicular crystals

4b.—Less highly vesicular, almost opaque, red in parts, in parts almost black by reflected light. Some feldspar rods scattered sparsely. Olivine freely developed, and some augite. Summit of island, in situ.

Armitage'S Sledge Party, Near New Harbour.

Medium grain, granitic texture, black mica, white feldspar. At one point within a little space four crystals of clear brown sphene, the largest 2·5 mm. by 1·25 mm. Biotite-mica, pleochroism pale olive-brown to very dark greens and browns. A little chlorite, developed at the expense of the mica. Quartz in coarse mosaic, fluid inclusions with small bubbles, some apparently empty cavities. Two classes of feldspar. The greater part orthoclase, but a fair proportion of plagioclase, probably ohgoclase. Both are very fresh in patches, much altered here and there. The plagioclase twinning shows the occasional shear of a crystal, and also considerable bending. Some apatite. Biotite-granite. Collected on the western sledge journey of 1902 by Lieutenant Armitage.

Western Mountains.

This collection numbers upwards of a dozen specimens, the wasters of a larger collection of loose rocks picked up by Dr. Wilson when on a sledge journey with Lieutenant Armitage to the southern extremity of the foothills of the Western Mountains forming the northern shore of the outlet of the Koettlitz Glacier. This journey was undertaken in December, 1903.

Western Mountains, 1.—Mica-schist, much dark mica partially leached and iron-stained. A gneissic rock of clastic appearance. Both feldspars and quartz are in interlocked granules, and both appear distinctly fresh. The feldspar is often striated (symmetrical extinctions 20°), and frequently penetrated by, or includes, needles of apatite. The quartz seems free from fluid inclusions. A few crystals of rutile occur. There is much mica, the more part intensely pleochroic from very pale pinkish-brown to rich red-brown; associated with this is white non-pleochroic mica, which in certain areas occurs in tracts of long bent blades, streaming in a uniform direction, and associated with patches of quartz and feldspar mosaic of fine grain, within which again are small patches of brown mica, otherwise excluded from these portions of the slide. It is to the white mica so developed that the marked schistosity of the rock is due. The whole slide gives evidence that the rock has sustained an intense crush—so intense, indeed, that the quartz-feldspar mosaic is at places reduced to a mere aggregate of powdered material.

Western Mountains, 2.—A grey rock of rough texture. A few feldspars are visible, but a rather dull brown-grey mica is by far the most prominent constituent. Much biotite. Face - colours vary from pale cinnamon-brown, with an occasional olive shade, to rich tints of brown in basal sections. Comparatively small patches and blades of hornblende are fairly frequent. The pleochroism is from pale olive to deep blue-green. Very numerous grains and some larger much-altered crystals of augite, showing slight pleochroism from bluish-grey to pink-grey. Large patches of calcite. All in a general confused groundmass of high double refraction, with serpentinous products. There is also, apparently, some secondary feldspar in mosaic form, and some sphene after titaniferous iron-ore. Dioritic lamprophyre.

Western Mountains, 4.—A dark basaltic rock. Groundmass pale brown. Consists of small brown augites and lath-shaped feldspars, with numerous crystals of magnetite. Some of the augite shows enclosures along both cleavages, giving well-defined dark lines. More or less this feature occurs throughout the slide. Olivine is present in much larger forms, colourless, occasionally with fair crystal outline, with inclusions of magnetite and sometimes of the groundmass.

Western Mountains, 5. — A thin slab, apparently of grey micaceous slate. Section cut parallel to cleavage. Much pale-brown mica, which, being largely cut parallel to the base, affords a fairly uniform tint throughout the slide, and appears as if filling the rle of a ground in which the other minerals are set. Exhibits moderate pleochroism, and in convergent light shows a slight separation of the cross into hyperbolae. Short prisms of tourmaline of pale-green colour are rather common, and are very uniformly distributed. There are numerous subangular granules of clear untwinned feldspar. Filling the interstices between the other constituents is a substance white by reflected light, mottled with palest green by transmitted light, showing crystal granular and fibrous structure with high tints between crossed nicols; the constituents are in much too minute form for identification. Dusty ferrite stains the slide in places, and magnetite is somewhat sparsely distributed throughout. Altered sedimentary.

Western Mountains, 6.—Soft brown rock, lighter in colour and softer after passing 9 mm. to 10 mm. from exterior. Glaciated. Contains rounded sand-grains. A bright brown tuff with rounded fragments of feldspar, some striated, and less-numerous olivine fragments. A few inclusions of white and black rock minutely speckled, and also of brown glassy rocks with feldspar laths. Tuff.

Western Mountains.—The collection also includes a fragment of kenyte; a granular felsite, apparently hornblendic; and some granites or diorites.

Granite Harbour.

Granite Harbour, 1.—Compact horny texture, dull - brown rock, evidently a felsite, with small pink porphyritic feldspars. Small dark spots (1 mm. largest) rather widely scattered. Mica in somewhat granular form. Groundmass minutely crypto-crystalline, pink in shade, strewn with green microlites (pleochroic from browner to bluer shades). The longer axes of these microlites lie in one general direction, and the mineral is almost certainly mica. A very rare grain of magnetite occurs. Porphyritic feldspars, some entirely clouded with red decomposition-products, others in parts quite clear and colourless with irregular streaks of cloudiness and a hatching of lines of same. The feldspars are clearly defined against the ground, and appear to be in large part microcline. Here and there the green mineral invades them in somewhat massive form, and it also fills cracks in the rock.

Granite Harbour, 2.—Fine-grained granitic texture, white feldspar, black mica, quartz slightly stained in places. Feldspars slightly clouded locally, practically all oligoclase. The quartz contains small fluid inclusions, with bubbles, and some empty cavities. Much brown mica; pleochroism pale straw to dark greenish-brown, almost black; gives practically uniaxial figure in convergent polarized light. Apatite prisms are frequent, in acicular form, the central parts much darkened by some dusty black substance, which lies mainly in a series of planes parallel to the base. Pale granular sphene, at times with a core of titanic iron-ore. Quartz-diorite.

Granite Harbour, 3.—Finer grain of “G.H., 2”; minerals apparently identical. The rock breaks in slab form, and the mica shows tendency to mark out a parallel structure.

Granite Harbour, 4.—The whole specimen is practically one mass of feldspar. No visible quartz. There is some dark mica partially leached and largely altered to chlorite, which occurs also lining a joint-face.

Granite Harbour, 5. — A grey rock, fine-grained admixture of dark greenish-grey crystals and dirty-white; the specimen is a thin slab. Grey-brown diallagic augite, ophitic, with very slight pleochroism. Between the augite plates, labradorite-feldspar in moderately stout forms, frequently zoned. Occasional patches of micro-pegmatite; no porphyritic quartz. Some ilmenite. Small widely separated spots of red-brown mica, associated with the augite. Quartz-augite-mica-diorite.

Note on Glacier-Recession, By T. V. Hodgson.

A great deal has been said and written about the retreat of the ice from north to south, and the glaciers from low to the higher levels. This has been based upon the fact that the edge of the Great Ice Barrier is some miles further south than it was when seen by Ross in 1839–40.

The various sledge parties encountered many glaciers the extremities of which do not reach the sea, or even come within reasonable distance of it. One fact must impress the Antarctic explorer, and that is the thinness of the ice-sheet and the large proportion of exposed rock. The thickness of the ice on the inland plateau is purely conjectural, and with the appliances of the average sledge party it would be impossible to measure it. Theoretical calculations have shown that ice cannot exist at a greater thickness than 3,000ft., and one feels—for one can do nothing else—when in those regions that there is no reason to believe that it might possibly be more than this.

I would ask, what right have we to accept so readily the assumption that the temperature-conditions are becoming less severe, and that therefore the ice-cap is receding? It appears to me that the evidence is very weak at the best.

To begin with the Barrier, the amount of recession is small compared to its enormous area. It is greatest on the eastern side, where we have absolutely no knowledge whatever as to the source of supply. As compared to the mountains of the west, King Edward VII Land, from the little that has been seen of it, is low-lying country, and if such should ultimately prove to be the case it may also prove to be the larger feeding-ground.

Only in one spot has the rate of movement of the Barrier been measured. It was a rather crude measurement on a sledge journey near Minna Bluff, and is probably only local; it works out roughly at about a quarter of a mile a year. There is no evidence whatever as to the seasonal fluctuations of this ice-sheet: a series of mild or of severe seasons seems to me to be amply sufficient to account for the difference in the position of its northern face. The icebergs met with by the “Discovery” were for the most part very small, and I think I am right in saying that none of them were over three miles long.

As to glaciers, many of them do not come down to sea-level, but end abruptly, frequently at some considerable distance from it, and it is very much open to question if they have ever been anywhere near sea-level.

These facts have been interpreted as proof positive that the glaciation of the region is receding, it being regarded as certain that in no very far distant