(a) Cape Barne

The ice-free area adjacent to this Cape is situated 33 kms NNW of Scott Base. Cape Barne forms a right angle in the coastline. Along the southern side are three partially dissected basalt cones, the most westerly exposed to the interior where two dykes and associated agglomerates have resisted marine erosion to form the Cape Barne Pillar. To the north, kenyte lavas have flowed westwards from sources high on Mt. Erebus. During Pleistocene times ice is considered to have cut two parallel arcuate valleys, concave to the west, within the kenytes, each about 100 ft. deep. These valleys now possess three lakes, and adjacent to them are steep cliffs which display a complex of polygonal joints radiating outwards from the centres of the kenyte lava flows. To the east, most of the bedrock outcrops are mantled with moraine, forming a hummocky topography with many distinctive debris cones.

Within the inner eastern valley a small pass of moraine separates two of the lakes. It is at this site, within and upon the surface of the moraine, that the fossils have been located. Consisting of three beds, alongside a prominent mirabilite deposit, the fossils consist mostly of molluscs, bryozoans, sponge spicules and foraminifera.

The kenyte forms an undulating topography with bedrock cropping out on the higher levels to form small tors which display well developed polygonal jointing. Within the hollows coarse sands have accumulated which are considered to represent the end product of salt weathering out the individual crystals within the bedrock to form 'lag gravels'. A thin morainic cover may be located in a few places which often contains diagnostic pale green kenyte erratics.

The moraine to the east extends northwards to form the coastline of Backdoor Bay and southwards to the Barne Glacier. Kenyte erratics are to be found on the basalt cones to the south, whilst two moraine mounds a little to the north are composed almost entirely of basalt with a few granite erratics. On steeper slopes only the coarse angular blocks remain as a scree, the fines presumably winnowed away by the wind. In contrast, the gentle lower slopes form more typical morainic lithologies of unsorted, chaotic masses of blocks, sands and silts which frequently form solifluction deposits.

Marine sands and gravels have accumulated at the seaward ends of the outer, western coastal valley. Here four raised beaches were levelled for height and distance from sea level.

The basalt cones to the south have been denuded to expose central dykes and breccias with interdigitating steeply dipping lava flows. A curved fault plane was discovered within the eastern cone, which is considered to represent a fault of similar structure to a cone-sheet dyke. Considerable controversy surrounds the age relationships between the basalts and kenytes. Smith (1954) draws no conclusions, whilst Treves (1962) considered the basalts were older. Our field observations were not conclusive, but there is a strong suggestion that kenyte overlies basalt at one locality. Between the two eastern basalt cones is a low saddle with an outcrop of kenyte bedrock, which we consider must be younger than the basalt. Furthermore, no basalt scoria or lavas were found upon the kenyte lavas.

Thus from our work the geological history of Cape Barne could be summarised into the following series of events:

(a)	Eruption of basalt cones;
(b)	Outpouring from flanks of Erebus of kenyte lava flows (at least three successive flows are visible near Cape page 16 Royds.
(c)	The cutting of the two arcuate valleys by an enlarged ice sheet, which occupied McMurdo Sound, with erosion of the seaward portions of the basalt cones.
(d)	The deposition of moraines over extensive areas of land behind the cape, less than 32,000 years ago.
(e)	The deposition of beach gravels and sands at both ends of the seaward valley prior to the postglacial rise in sea level. This is assumed because the present lake within the valley is beneath present day sea level, and there is no indication of a former, larger lake which has decreased in size to its present form.

Detailed petrological and geochemical examination of the rock types is proceeding at present, together with identification of fossil molluscs and bryozoans collected from within the inner valley, and also at two localities within moraine along the coast of Backdoor Bay.

(b) Cape Bird

The excursion to Cape Bird (40 kms north of Cape Barne) proved more rewarding than expected. A number of fossils have been recorded here previously by Speden (1962). Belonging to the Scallop Hill Formation, they are presumed to belong to at least the Penultimate Interglacial, and have since been uplifted to at least 600 m above sea level. They are now found within moraines being deposited by the Mt. Bird ice cap. A search throughout this area revealed many of the fragmented pectens (Chlamys andersoni) and bryozoans collected previously, together with the rarer solitary coral Gardineria antarctica and a whale bone about six inches long.

Traversing along the coastline to Cape Bird B, twenty-three successively raised beaches were discovered, and considerable time was spent in measuring these features along a number of parallel traverse lines. The formation of the beaches on this spit is considered to have formed by a current flowing around Cape Bird from the east, eroding and carrying material along the coast (probably by longshore drift) until it reaches the principal northward current of McMurdo page 17 Sound. Here the gravels have been deposited and under favourable weather conditions the moving ice flows express the surface currents exceedingly well.

The highest of the sequential raised beaches was only about 6.9 m above sea level, but raised beaches found at other localities along the coast range up to 11.4 m a. s. l.. A bench found between 36 m and 39 m a. s. l. is attributed as being of Last Interglacial age.

A one day excursion was made to the more southerly region of the ice-free area at Cape Bird. Here a number of quite different volcanic rock types are exposed (Cole and Ewart 1968), and a collection was made for detailed geochemical work. Rock types include hornblende - pyroxene trachytes, olivine basalts and olivine - augite basalts. Additional features observed and described along the coastline include gravels being deposited by the ice-foot (the rim of ice along the shoreline). Samples have been obtained (in conjunction with the Waikato and Canterbury Expeditions) of soils developed on variously aged, raised beaches from the Northern Penguin Rookery to compare the effects of addition of guano to the regolith.

Dr. C. Hendy is intending to radiometrically date a number of the beaches (assuming that the penguins are rapid colonisers of ice-free areas as soon as they become available). If this dating is successful, it will enable us to determine the build-up of concentrations of major elements at the sites with respect to time. This may form an interesting chronosequence with few variables involved in the system. Such opportunities are rare.

(c) Cape Crozier

Little geological field work has been attempted at Cape Crozier, and since 1957 the area seems to have assumed a 'biological playground' function with the large number of penguins nearby. The cape is located on the most easterly extremity of Ross Island and is about 70 kms northeast of Scott Base.

Only one fossil - a gastropod, has previously been found at Cape Crozier, but a search in the area did not reveal any further fossils. An outcrop of tuffaceous sandstone was discovered adjacent to Post Office Hill, samples of which will be submitted to the recognised experts for microfaunal and microfloral analysis. Three page 18 raised beaches were also measured at the Northern Penguin Rookery to the north and south of Williamson's Rock.

The rest of our time was spent on the volcanic geology of the coastal section at Crozier. The area mapped was a 9 km strip of land, about 6 km wide, which extended up to an altitude of about 600 m a. s. l., but not including the 150 metre high cliffs which fringe the sea. This mapping was possible because a base-sheet existed of this area, prepared by Lands and Survey Department, Wellington.

The two principal cones in this region are The Knoll and Post Office Hill, both composed of trachyte. In both cases a small crater is preserved at their summits, and The Knoll crater contains a frozen lake. Basalt has been erupted from The Knoll as a late phase of activity, forming thin black flows over the steep-sided, light yellow trachyte. On a nearby basalt cone spirally twisted volcanic bombs were located. Further to the north another basalt cone is exposed to show a trachyte dyke. From this type of evidence the age sequence was established. Detailed examination of these interesting and important rock sequences will proceed shortly when the specimens arrive back in New Zealand.

Many more basalt and trachyte cones extend eastwards along the flanks of Mt. Terror, almost to the summit. These cones remain unmapped, but a request has been made to U.S. Geological Survey, Washington, to obtain aerial photographs of this region.

A great variety of lichens were found at Cape Crozier, including red, yellow and green crustose types and a black and green fruiticose lichen.

At this point it should be noted that the detailed examination of the volcanics was limited to Ross Island. Here the Tertiary and Quaternary volcanic rocks constitute the McMurdo Volcanic Group, page 19 a suite of rocks quite different from those occurring in the North Island of New Zealand. Whereas the North Island andesites and rhyolites belong to the calc-alkaline suite of volcanics more typical of orogenic areas, the alkaline suite of the McMurdo Volcanics is more typical of continental volcanic areas.

Ross Island consists of the central basalt - kenyte cone of Mt. Erebus (3,794 m) which is symmetrically surrounded by three volcanic lineations characterised by a basalt - trachyte - basalt sequence of eruptions. These three lineations consist of the Mt. Bird (1,766 m) eruptive centre to the NNE; the easterly lineation of Mts. Terra Nova (2,130 m) and Terror (3,230 m) to Cape Crozier; and to the SSE, the Hut Point Peninsula lineation. Samples collected by Scott's expeditions (Smith 1954) showed the basalts of the Erebus vent to be different from the surrounding linear vents. The dissimilarity of Mt. Erebus from the eruptive centres of Cape Bird, Cape Crozier, and the Hut Point areas offers an interesting problem requiring detailed geochemical and petrological investigation of samples collected. This study is planned for this year's laboratory research work.

(d) The Labyrinth and the Lower Taylor Valley

Both the above localities are in the Dry Valley Region, some 150 kms NW of Scott Base. The surfaces at the western end of the Wright Valley are all structurally controlled by the inter-bedded Beacon sandstones and Ferrar Dolerites where a broad platform of dolerite is exposed called the Labyrinth. This particular 'bench' of dolerite has been eroded to form a system of steep walled canyons which anastomose within the dolerite lithology only. Conjecture as to the processes forming it have been many and varied. Our limited investigations there (due to support problems) suggest the Labyrinth was first exposed by glacial action by a previously expanded Upper Wright Glacier. During this cutting many of the accordant cirques to the north and south probably formed. Later development of the box canyons seems to be predominantly an 'in place' erosional process whereby the dolerites are broken down into their individual components. Small potholing within dolerite pebbles in the Labyrinth clearly display how the wind erodes the coarser crystals from the dolerite.

Whilst at the Labyrinth our ideas on the geological history of the region were formulated with respect to data from the Taylor page 20 Valley (about 85 kms from Scott Base). Recent American literature shows that volcanics were erupted 2.7 million years ago in an ancestral Taylor Valley (Armstrong, Hamilton & Denton 1968). This clearly indicates that pre-Pleistocene glaciations existed, and we therefore collected the highest basalt and kenyte erratics we could find in the Lower Taylor Valley. Dating of these volcanics could assist in interpreting whether events in the Lower Taylor match those in the Middle Taylor Valley. Such an assumption was made by early reconnaissance workers, but has yet to be validated. A potassium-argon (K/Ar) date of these samples would give a maximum date to these deposits. (See page 22).

Together with Vucetich and Topping, the Pleistocene sediments in the Lower Taylor Valley were sampled to see if there are any marine microfossils present within these sediments. Micro-faunal examination may support the hypothesis that these sediments were deposited in a fiord, and that they have since been uplifted above sea level. Alternatively, they may have formed in a huge lake. Microfaunal analyses are to be completed by Dr. P.N. Webb (N. Z. Geological Survey) on foraminifera, Mr. W. Briggs (Geology Department, V. U. W.) on ostracodes, and Neall on bryozoans.

The type locality of the Taylor Formation (Speden 1962) was also examined. The distribution of the deposit has been extended, our investigations showing that shells are in situ up to 9 metres above sea level. They are located at most points along the coastline of the mouth of the Taylor Valley. In all cases they are marine deposits on moraine, and they are not found in areas subjected to flooding or the build-up of deltas. A detailed map of these localities will be published later. Shells found in these deposits include Adamussium colbecki, two other genera of bivalves, an as yet unidentified gastropod, and two complete echinoderms. An age determination for these shells may assist in determining the rate of uplift of this section of the coastline.

(e) White Island

White Island (25 kms south of Scott Base) is mostly aproned by glacial moraine. Fragments of the pecten Chlamys andersoni, and worm tubes were located at the northernmost point, as found by Speden (1962). Undoubtedly the same fossils as the Scallop Hill Formation, they range up to 54 m a. s. l.

The most conspicuous features on White Island are five page 21 glacial benches on the north side of the island. These were measured in altitude using a barometer and are at approximately 114 m, 177 m, 246 m, 300 m and 340 m above sea level. None of these features could be correlated with distinctive moraines reported from Black Island by Vella (1969). No diagnostic kenyte or Tertiary fossiliferous erratics were sighted. It can only be suggested that the Black Island benches were cut by an expanded Koettlitz Glacier, whilst White Island has been subjected to the Ross Ice Shelf.

A few volcanic rock samples were collected from the north facing cliffs and from the summit of Mt. Heine for further detailed work.

White Island would appear to consist of at least two coalescing basalt shield type volcanoes which have been eroded by cirque development at a period of lower sea level. The two vents lie along a north-south line, with the northern vent represented by a large oval crater on the northwestern side of the island. The later history is dominated by the building of many small basalt cones with their remnant craters scattered over most areas of the island. From the general topographic appearance and the lack of trachyte eruptions, it is considered that the island is the last phase of the basalt - trachyte - basalt sequence noted by Cole and Ewart (1968) on Black Island and Brown Peninsula (both of which lie within 30 km to the west of the island), White Island is probably considerably younger in age than either of the latter two areas.

(f) Hut Point Peninsula

Two days were spent investigating rock outcrops to the north of Scott Base. Cole and Ewart (1968) completed a survey of the geology of Cape Bird, Black Island and Brown Peninsula, and to complete this work along the west side of McMurdo Sound we examined the geology of Castlerock and the outcrops to the north, along the central portion of Hut Point Peninsula. Wellman (1964) has previously studied the surficial geology of the area. Castlerock is composed of a complex autoclastic palagonite breccia, which is presumed to have formed in the throat of a volcano, and it has later been intruded by a small dyke. Most of the other cones were basaltic, with some craters displaying fine examples of once molten volcanic bombs. A new outcrop of trachyte was located, and a breccia similar to that composing Castlerock was found to the south page 22 behind McMurdo. The famous sponge spicule balls were still located in this region (Wellman 1963). It is hoped that this sampling of volcanic rocks together with those from Capes Barne, Royds, and Crozier, and White Island can be combined to complete the regional reconnaissance of the volcanics.

(g) Potassium - Argon (K/A) Dating

It may be possible for a small number of volcanic samples collected by VUWAE 14 to be submitted for K/A dating. The following samples are considered well worthwhile being dated for the following reasons:

(1)	Kenyte from the highest moraines in the Lower Taylor Valley - Dating of this sample could give a maximum age to some of the glacial events in the Lower Taylor Valley.
(2)	Basalt from Cape Barne - This would give some indication of age relationships between the basalts and kenytes, as well as giving information about erosional processes. The kenyte is being dated for paleomagnetic work in the United States.
(3)	Basalt from White Island - This sample dates the oldest rock in the stratigraphic sequence recognised at the northern end of White Island. It gives a maximum age to cirque development as well as to the regional volcanic stratigraphy.
(4)	Trachyte dyke from basalt cone at Cape Crozier.
(5)	Basalt cone intruded by above dyke - Clearly, when such a well exposed relationship is established between two contrasting rock types, it is imperative to investigate their relative ages. These two samples represent a pattern observed at a number of localities at Cape Crozier, and they are considered to be representative of the area. An indication of the general stratigraphic sequence may assist in correlations to volcanic events studied by Cole and Ewart (1968).
(6)	Basalt dyke from Castle Rock, Hut Point Peninsula - page 23 From topographical evidence this rock may well be the oldest feature of the area. Composed principally of autoclastic breccias, a small dyke has intruded these rock types, thus dating the last phases of activity preserved at this locality. Again, dating would assist assessments of the rates of erosion in the region.
(7)	Basalt from Cape Bird - This sample was selected because it dates the main cone-building phase of Mt. Bird. Comparison with samples from Cape Crozier, Hut Point Peninsula and Black Island will give comparative data on the build-up of these volcanic lineations and assist in comparisons with the sequence of Cole and Ewart (1968).

Another three samples are to be submitted by Dr. J. W. Cole from those collected by VUWAE 9 on Black Island (see Cole and Ewart, 1968).

It is hoped that all these samples will be dated at the Institute of Nuclear Sciences, Gracefield. Material will be submitted for whole rock analyses except the kenyte which will be determined on the extracted anorthoclase phenocrysts.

(h) Recommendations for future scientific projects

1.

As a follow-up to our investigations a tentative programme is suggested for VUWAE 16 for 1971-72. This is to examine the volcanics exposed above 2,000 ft altitude at Cape Crozier, when photographs will then be available from U.S. Geological Survey. A visit to the Upper Koettlitz Glacier region could also be incorporated into this expedition to search for kenyte outcrops presumed to exist on Mts. Morning and Discovery. The source of the kenyte in moraines in the Lower Taylor Valley and at Black Island is presumed to have come from the Koettlitz region, but now some confirmation is required of this assumption by the early geologists. Examination of rock types on the flanks of Mt. Discovery could also be encompassed on this expedition, enabling a petrologist to carry out the first detailed sampling of this area. Collection of these samples could prove a valuable contribution in the understanding of the geochemistry of the McMurdo Volcanics and may also reveal some extremely important outcrops of kenyte. It is this type of "specific problem" research which is required in the future to solve the more page 24 difficult and less glamorous questions which have been left unresolved by earlier workers.

2.

In conjunction with geophysical research on the sea and shelf ice, an interesting study could be made by a Victoria student of the sediments which now mantle the sea floor of McMurdo Sound. Geophysicists are continually probing through the ice and collecting sediment samples for experimentation; biologists are continually dredging the bottom to collect invertebrates and divers scan the bottom waters examining seal behaviour etc. It seems about time that a sedimentologist collate the wealth of unusual information available to prepare a sediment map of the Sound.