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The main aim of VUWAE 24 was to provide the scientific support for coring the floor of Western McMurdo Sound, an enterprise that would involve close collaboration with the Ministry of Works drilling team and the logistic services of Antarctic Division. In addition scientists from four other countries were to participate. The object of the drilling was to obtain a record of the early history of the East Antarctic ice sheet and hopefully reach strata predating its formation (Barrett, 1979). Preliminary results are given in Part I of this report. The planned programme also included a variety of investigations after drilling was completed. Some of these, such as the gravity and seismic surveys, were scientifically related to the drilling; others were mainly to allow scientists already in Antarctica for the drilling to exercise their skill and curiosity further. Post-drilling programmes of both types are described in Part II.
Because of the integral nature of preparations for the drilling and the subsequent field events they are discussed together below.
A grant of $14,000 was obtained from the University Grants Committee to pay for food, clothing, camping items, scientific equipment, travel, freight and insurance. However, this was not sufficient for both the drilling project and the subsequent field programme that developed. The University's Internal Research Committee made a further grant of $530 in addition to its grant to student assistants, the Geology Department paid for repairs to a theodolite, and the Physics Department purchased a $500 share in the "Mate" earth/ice auger. The running grant of the Antarctic Research Centre was also used to help cover the gap, our total budget for the season being $16,300, despite a range of economies in purchasing.
A grant of $1,388 was also made from the Trans-Antarctic Association to help the participation of Dr McKelvey, sedimentologist, and Howard Brady, micropaleontologist.
Equipment bought for VUWAE 24 was mainly scientific used in conjunction with the MSSTS project for sea floor sampling and the cross Sound Surveys. A "Mate" motorised earth auger with accompanying 4 and 10 inch diameter augers was used to make access holes through the sea ice. We also purchased a meter wheel for measuring toboggan travel accurately which was used in the cross Sound Surveys. Also purchased were six hundred metres of low stretch terylene cord used for depth sounding and two thermometers for the VUWAE Thommen 3B4 altimeters.
Several pieces of equipment were built, some of which incorporated borrowed equipment. The Oceanographic Institute camera and flash units for photographing the sea floor were fitted inside pressure vessels built by the VUW Engineering Workshop. A tripod was also made to lower the camera and piston cover to the sea floor. Nick Thompson built for us a very successful tide gauge used at the MSSTS drill site, and also modified the piston corer.
Antarctic Division (DSIR) supplied expensive and specialised equipment. The main items were vehicles, snow-trac and toboggans used during the across Sound Surveys, and on the Taylor Glacier Gravity Survey following MSSTS. VUWAE 24 field programmes (post MSSTS) were supplied with: Polar tents (4), two man tents (2), SSB radio transceivers (4), first aid kits (4), assorted climbing equipment and fuel (petrol and kerosene).
VUWAE 24 was charged by Antarctic Division on a man-week basis for food while at Scott Base and in the field. The weekly rate this season was $32 per person.
The MSSTS project has put a greater strain of VUWAE field equipment and clothing resources than for the smaller manpower expeditions of normal years. Old clothing normally used for repair materials were repaired to accommodate the increased manpower of this expedition. Much of the clothing has suddenly become redundant earlier in their life than usual because of the rigorous conditions of drilling. New clothing therefore needs to be purchased for the coming season's expedition.
Coring began: 21 October, 1979
Coring ended: 22 November, 1979
Position: 77° 33′ 25.83″ S; 164°23′ 12.85″
Water depth: 196 metres
Drilled depth baton, sea floor: 229.6 m
Number of cores: 73
Percentage core recovered: 44%
Oldest sediment cored:
Depth below sea floor: 229.6 metresLithology: Stratified, muddy, very fine sand with rare small pebblesAge: Middle Miocene
Two of the outstanding problems in Antarctic earth science are the early history of the East Antarctic Ice Sheet and the history of the Transantarctic Mountains, and they may well be linked. The GLOMAR CHALLENGER made the first major breakthrough in 1973 by recovering cores from the centre of the Rose Sea showing that ice rafting began there 25 m.y. ago and has been going on ever since (Hayes et al., 1975), but whether the floating ice came from East or West Antarctica is still debated. The cores contained little information about the history of the Transantarctic Mountains because the holes were too far offshore, and there is unlikely to be much further information from on land, for no dateable sequences from the key time period (50-10 m.y.) are known to crop out on land in the McMurdo Sound region. The glacial history and the uplift of the mountains are likely to be best recorded in the thick sedimentary sequence seen in seismic profiles along the Transantarctic Mountain Front (Northey et al., 1975). This sequence can be sampled only by drilling.
The first attempt to core this sequence (DVDP15) reached 65 m sub-bottom before sea ice conditions terminated drilling (Barrett et al., 1976). The second attempt, which is described here, was much more successful, though drilling was again terminated by sea ice conditions before the target depth was reached. Further background to the drilling can be found in Barrett (1979) and in the Scientific Operations Handbook (Barrett s Waghorn, 1979). Personnel for the operation are listed in Table 1.
Field operation of the MSSTS programme began with the arrival of an advance party of ten, including one from VUW, at Scott Base on 28 August 1979. Vehicles and equipment were prepared and a series of reconnaissances undertaken by Power wagon and Snotrac (Fig. 2). A flagged route closely following the southern and western boundaries of McMurdo Sound was established from Scott Base to New Harbour. Rough ice prevented an initial attempt to establish a route directly out to the MSSTS 1 site from the dump of DVDP drilling gear at Rig Point on the northern shore of New Harbour. During a Subsequent reconnaissance good travel was found on a route bearing 030 true from Butter Point.
On September 19 a reconnaissance party arrived at a point at 77. 33.3S:164 23.4E. The locality of the site was reached by dead reckoning and the position on the sea ice was fixed by resection using a Kern DkM 1 theodolite. Although 3 km SW of the proposed site (Barrett, 1979) the site was logistically preferable, being nearer land, and scientifically acceptable, being within the region previously surveyed by seismic refraction methods (McGinnis 1979) and known to have at least 500 m of sediment overlying basement.
Sea ice thickness at the adopted site, 1.98 m, was more than sufficient for drilling operations; water depth was 196 m and not varying from this by more than ±10 m at points 50C m north, south, east and west. The site was 80 km by sea ice road from Scott Base and 26 km from Rig Point.
Two huts were established at the site and an attempt was made to flood the area with sea water to strengthen the sea ice platform. The attempt failed as the pumps froze - the air temperature was −35° C. In the following weeks equipment and fuel were brought to the site by D4 sledge trains from Scott Base, McMurdo Station and Rig Point. By October 10 the camp, consisting of two oil-heated Jamesways and six insulated plywood huts, was fully operational and most of the drilling gear was on site. The main party of drillers arrived on October 12 and the erection of the rig began immediately. Casing was lowered to the sea floor on October 20 and drilling began on October 21.
The procedure for extracting core from the core tube varied depending on the core size being drilled. HQ core (dia. ≈ 63 mm) was recovered in a split tube ("splits") within the core tube. The 10 foot long splits containing core were hydraulically extracted from the tube and transferred intact and unfrozen onto the specially constructed bench in the Science Hut. The smaller sized NQ & BQ core tubes did not have splits. Core therefore was directly removed from the tube onto an HQ 'split' by gently tapping the tube and extruding the core with a steel rod. Often the tube had to be heated in a "Herman Nelson" hot air hose to unfreeze water surrounding the core before extraction could proceed. NQ & BQ cores therefore suffered some sub-horizontal fracturing resulting from core extraction. These fractures, however, were fresh and easily distinguished from natural fracturing within the core. Boxing, initial examination and description was done on the unfrozen core in the Science Hut.
The primary purpose of the onsite description was to record as accurately as possible the depth from which core was recovered and any features which might be changed by freezing and transportation to the core lab.
Information from the driller often enabled a more accurate determination of from where core was recovered during the coring run. This was particularly important when recovery was less than 100%. The position of core recovery was shown at the graphic log, a double line being used to indicate the bottom depth of the run when the run was not the full 10 feet. When doubt existed about the exact depth of "the core, it was assumed to have come from the top of the run.
Fracturing was noted on the graphic log and where possible determined as natural or induced from drilling and core extraction. Some mudstone lithologies initially recored and intact cylindrical blocks suffered extensive conchoidal fractures on subsequent freezing.
The colour of the core was compared with the "Revised Standard Soil Colour Charts" (Japan). Bioturbation and bedding was often most easily seen when the core was fresh and wet.
Routine on-site measurements of sonic velocity, density and chemistry of the core were planned. Due to low and fluctuating temperatures in the Science Hut and the cramped space, only sonic velocities were finally performed. Sonic velocity measurements were undertaken with a PUNDIT, determining the travel time between two transducers of an 82 kHz pulse, as described in Barrett & Froggatt (1978). Only whole, coherent segments of core free from fractures or clasts and at least 50 mm long were chosen. Sampling between transducers and core was improved by washing measuring points on the core with water and use of water as a complant. Grease or oil was avoided to lessen core contamination. Consistent readings about the core axis were obtained in this manner. Measuring was performed as soon as possible after cote recovery, usually as soon as the core was boxed and before initial logging. Except for Core 2, the cores remained unfrozen. Time after recovery was usually less than one hour although delays of up to eight hours occurred.
Velocities measured ranged between 1.78 and 5.10 km.s−1 for sediments and 3.44 to 5.92 km.s−1 for basement clasts of dolerite, granite etc. Clast velocities agree well with the data of Barrett & Froggatt 11978). However, sediment velocities were generally higher than determined from seismic refraction profiles in McMurdo Sound (Barrett 1979, Nor they et al., 1975) and more varied than for DVDP 15 where many of the cores were frozen (Barrett s Treves, 1976). Velocities determined on each core or unit within a core have, initially been averaged (Table 2) and plotted against depth (Figure 3). A steep uniform velocity gradient of V = 19.OH + 1.6 (V = velocity in kms and H = depth in km) is shown to 110 m sub-bottom where there is a marked velocity reversal. A further reversal occurs at 190 m. Reflectors labelled A, K, B & C (Northey et al., 1975) have been tentatively identified at 141 m, 168 m, 180 m and 210 m sub-bottom respectively. The lithology of each reflector is a well
−1, compared to 2.0 - 3.5 km.s−1 for less cemented material adjacent to the reflectors. There is no apparent correlation between these reflectors and lithologic units. There is an overall good correlation, however, between lithology and reversals in the overall velocity gradient.
Sonic velocities determined with the PUNDIT were found to provide quick, easy and reliable measurements on the core. These allowed the actual Velocity profile to be built up as drilling proceeded with consequent readjustment of projected target depths using the available seismic reflection records. Only reflectors A, C, & D were recognised on the reflection profiles beneath MSSTS 1, so once A had been penetrated, adjusted velocities gave projected depths of C at 204 m and D at 270 m sub-bottom. Based on two-way travel times from Track XXII (Northey et al., 1975) depth estimates were revised after each reflector was recognised. Calculated and actual depths are compared in Table 3. General close agreements between depths indicates reliability of average core velocities.
The gas composition dissolved in circulating water from drill hole has been analyzed by using a gaschromatograph (Shimadzu GC-30AT) coupled with a pen recorder. The amounts of O2, N2 and CH4 are measured by a Molecular Shieve 5A column, and those of air Components (O2 + N2). CO2, CH4 and C2H6 by a Porapac-Q column.
The equipment was set in a small hut placed just near the drill-rig. The gas analysis was made at constant column temperature (15°C). Helium was used as carrier gas.
The time table of working at drill site is:
Nov. 1-2 Set-up of equipments at drill site
Nov. 8-17 and 20-23 Analyses of gas composition of water and ice samples.
Because the drilling condition was not good at the time of Nov. 8-23, only five measurements were made for circulating water from the bottom of drill hole. Gas composition of room air, atmospheric air, and dissolved gas in sea water were also measured for comparison.
Preliminary results are summarized in Table 5. As seen from the table, CH4 and C2H6 were not found in circulating water samples. Low oxygen contest (6–15%) and rather high CO2 content (1–6%) are commonly observed for water samples except for sample no.5, the gas composition of which is the same as that of sea water. However, main components (O2 and N2) are not much different from the atmospheric air. This fact suggests that the dissolved gas in the circulating water is mainly from atmospheric air, probably sucked in by the pump used for water circulation. The low oxygen content may have caused by contact of sucked air with the down hole sediment, which is in a highly reducing state.
Four bench marks number BM1 to BM4 were established on a line bearing 300° and situated at 25, 50, 100 and 200 metres respectively from the rig (Fig. 3). These, together with a point on the Science Hut 10 m from the rig and a point on the rig itself were levelled throughout the drilling operation. Until October 19 a Kern DkM1 theodolite was used, thereafter a Wild level; observational error is estimated at less than ±5 mm. Differential vertical movements of all stations relative to BM3 are plotted in Figure 4 which shows that BM1 and BM2 descended rapidly with respect to BM3 in the period October 10 to 19 when weight was being concentrated at the rig. There followed a 10 day period during which a small but significant rebound occurred. This was greatest and most pronounced at BM2, the farthest station from the rig measured other than the datum bench mark BM3. After October 28 BM1 & 2 and the Rig show a consistant subsidence relative to BM3 while BM4 had risen, Which is taken to indicate that BM3 in fact descended relative to sea level and that the zone of subsidence due to loading at the rig exceeded 200 m in diameter. The total subsidence of the rig relative to BM4 in the period October 28 to November 21 was 65 mm.
Late in the drilling operation when snow had ablated from the sea ice surface a number of old healed cracks were discovered in a region 40 m from the rig. In contrast to the experience at DVDP 15 no relative movement was observed on any existing cracks and no new cracks in the vicinity of the rig or camp were observed during the entire operation.
As at DVDP 15 differential slackness on the guy ropes of the drill mast occurred. The slack guys were on the side of the mast loaded by the main lifting pulley. The amount of slackness increased with load and was attributed to deformation of the mast.
Ice thickness was monitored and is graphed in Figure 4. On September 19 when the site was first visited the ice was 1.98 m thick. The ice thickness increased to 2.33 m by November 14 after which there was a slight decline to 2.28 m at the termination of drilling. All thicknesses were measured in a small region about 10 m from the rig. During the bathymetric survey of the drillsite, ice thickness was measured in 16 holes and found to be the same to within 20 mm over the entire area.
On October 8 during a 30 hour break in drilling, downhole temperatures were measured using a thermistor and bridge circuit on loan from the Physics Department, VUW.
Seven temperature readings at known vertical spacing were obtained in the hole plus two further readings in the water column above.
The thermistor was calibrated prior to the field season with cable and bridge held at room temperature (about 15°C] and only the thermistor temperature lowered. Using this calibration a temperature of −3.3°C was obtained for the seawater above the hole. As it is known that the water temperature in McMurdo Sound is remarkably constant at −1.8°C it appears that either the instrument had drifted since calibration or the bridge circuit was affected by low ambient temperatures. A re-calibration was made on site using Mercury thermometers and a commercial thermistor temperature probe. The new calibration curve was approximately parallel to the old but gave a temperature for seawater closer to the expected value of −1.8°C.
Downhole temperatures derived from both calibrations are plotted against depth in Fig. 5. Absolute values of temperature are known to be in error but the estimate of temperature gradient is not thought to be badly affected. The gradient, 35°C/km, is slightly higher than the value of 31°C/km obtained at DVDP 15.
A tide gauge consisting of a line anchored to the sea floor and running over a pulley suspended above the sea ice (Fig. 6) was set up in the Science Hut adjacent to the rig. Tidal movements were recorded by taking off the movement through a pulley reduction system onto a chart recorder. Usable records were obtained for the periods 1 to 25 September inclusive and 1 to 24 November inclusive. Until 9 September a reduction of 13.6:1 was used, thereafter 10.1:1. The maximum tidal amplitude was 0.89 m. In addition to the main tidal variations with periods of about 24.20 and 12.20 hrs small cyclical movements with amplitudes of a few mm and periods of 5–50 sec occurred. These are attributed to attenuated ocean swell and were too small to be measured by the recorder.
Water depths were measured by weighted metre line on a, 200 metre grid surrounding the site. Results are summarized in Figure 7. The sea floor around the site has a very subdued topography with an approximately north-south strike and gentle dip to the east.
Three student members of VUWAE 24 worked as offsiders on the Longyear 44 drill rig alongside MOW drillers during the MSSTS project. Shift work began on October 16 in 8 hour shifts with one VUWAE member in each of three of the four drill crews. Some of the jobs done by the student offsiders are described below. The rig set up is shown in Figure 8.
Two ten foot lengths of drill pipe were joined to make 20 foot "stands". This was accomplished by means of chain vices and stilsens.
Floor work in the drill shack included joining and breaking of "stands" to and from the drill string, monitoring pump pressure, and general maintenance.
Derrick work consisted of detaching the winch howser from the "stands" while "tripping out" (removal of the entire drill string from the hole), and attaching it while "tripping in". This was often very uncomfortable as the derrick was exposed to all weathers.
Core pulling, or "grabbing" included breaking the drill string and lowering a light wire line with an "overshot" attachment down the hole. The "overshot" latches onto the core barrel, which is then pulled up the hole by winch. The core was then removed from the barrel by a high pressure water jet or other means.
Mixing of mud was always enjoyable, though often rather more grubby. This consisted of mixing the various drill muds and gels in the mud tanks with the help of motorized stirrers. The mud was then pumped down inside the drill string, returning up the casing and bringing with it rock clips from the drilling.
We also acted as general "dogs body", which included any tiling from getting the coffee (and not forgetting the biscuits) for smoko, to refuelling the rig and pump at the end of the shift.
The VUWAE members also assisted in the packing up of the camp and dismantling of the rig. All rig gear and camp buildings were dismantled and towed on sleds by D4 caterpillar back to Scott Base. Because this was such a long (9 hours), slow, monotonous and potentially dangerous trip, the D4 was escorted by a student in a Snotrac. "Riding shotgun" was at times a rather tedious task but enjoyed by most as it gave an opportunity to be relatively alone and reflect on the Antarctic surroundings.
Forty-one boxes of core were transported from the drillsite to Scott Base by U.S. Navy Helicopters, Power Wagon and octago sledge pulled behind by a D4 crawler tractor.
Although some core damage has occurred, mainly in the larger size HQ and NQ cores, this is attributed to drying out of the core, rather than damage due to transport. No difference in core preservation was observed between the different modes of transport.
The first 2 1/2 metres of core recovered, considered to be from a frozen layer deteriorated rapidly. No deterioration in the consolidated material occurred.
Storage and processing at Scott Base:
The core was processed and stored in the carpenter's shop at Scott Base. The sequence of processing was as follows:
Transport to New Zealand:
Core boxes were packed into a wooden cargon which was consigned from Scott Base about the 5th of December.
It was despatched from Christchurch on the 7th December, by rail to Wellington where it arrived on the 21st December. The cargon was picked up by carrier and arrived at the Geology Department on 28th January.
Core condition:
Little physical damage to the core occurred during transport back to New Zealand although a fair amount of relative movement of core pieces occurred within individual boxes.
A preliminary investigation by Dr Ann Bell (Botany Department, VUW] showed the presence of Hyphomycete fungi in four of the forty-four boxes, growing on core labels (gummed paper) wooden blocks and in some cases on the core.
Fungi growing on the core labels was either Penicillium sp or Paecilomyces while an Actinomycete, possible a Streptomyces sp, with very fine hyphae and chains of cauidia was growing on the core. Neither organisms could be mistaken for pollen grains.
Duplicate photographs of boxed core were made with both FP4 black and white film and Ektachrome 200 colour slide film. The core was photographed following the insertion of wooden blacks showing core number and sub-bottom depth and where possible prior to both core description and sampling.
Two 35 mm cameras with 50 mm lenses, mounted 1.1 metres above the core on adapted tripods were used. A Sunpack model 411 electronic flash was used for lighting with a double layer of tissue taped to the front to diffuse the light. A centimetre scale, Kodak colour separation guide and grey scale were used and are visible in each photograph.
The black and white film was processed at Scott Base and printed on 10 × 8 Ilfospeed grade 3 paper. These photographs were found to be extremely useful for both locating sample positions and for general use.
Colour film was processed in New Zealand.
535 samples for ten investigators were collected from the core during the drilling period (Table 6). Each sample is recorded in a sample register and the position labelled with the investigators initials in the core box. This should enable sample localities to be accurately located even if some disturbance of core occurs during transport or handling.
Samples have been defined by core and sections numbers respectively and measured in centimetres from the top of each section. Sub-bottom depths for each sample are calculated by adding this distance in centimetres to the sub-bottom depth of the section top.
The detailed cote description was carried out at Scott Base, and the summary logs on a scale of 1:50 are being prepared along with photographs of the boxed core, for publication in the VUW Antarctic Data Series. A log of the hole with the main lithologies is given in Figure 9.
Although a procedure for description was outlined in the Scientific Operations Handbook, pressure of time, facilities and differences in background of the four people involved lead to some unevenness in the descriptions. This problem is being overcome by reference to the core to check the summary logs. However, it is now clear that it would have been more satisfactory to carry Out a small full description at the drill site.
The strata cored at MSSTS 1 represent a moderately varied sequence of diamictite, muddy sandstone, sandy mudstone and well-sorted sandstone in units from a few to about 30 m thick. Pebbles and a few cobbles are scattered throughout, floating in the mud and sand and indicating a continuous glacial influence in sedimentation. Preliminary paleontological data [HTB; SML, BLW in this report] indicate that the sequence is entirely marine and. from 32 m to the oldest core, is mid-Miocene in age. The younger strata are Pliocene to decent in age. The MSSTS 1 core contrasts with the Late Miocene-Recent cores from nearby DVDP 10 and 11, in lower Taylor Valley, in that it is wholely marine, the amount and size of coarse debris is less and there is much less textural diversity.
Three main lithologies are recognised in the core recovered; diamictite, muddy sandstone or sandy mudstone, and sandstone. The diamictite is characteristically a non-stratified, very poorly sorted muddy sandstone with evenly scattered pebbles and cobbles forming 1 or 2 percent of the rock. However, all diamictite units include some intervals of stratification. The muddy sandstone and sandy mudstone units also have scattered pebbles, but are better sorted and lack the granule and coarse sand components of the diamictite, and are widely, if faintly, stratified. An indistinct mottling, attributed to bioturbation, is also common. The third lithology is the non-stratified homogeneous well sorted medium grained quartzose sand that forms unit 12. It is far more mineralogically and texturally mature than any other sediment encountered, the size and roundness of the groups indicating direct derivation from the Devonian quartzose sandstones 50 km inland.
Soft sediment deformation occurs in many parts of the core, but is more marked in Units 9 and 10. Three types are recognised:
In situ brecciation of at least partly lithified strata, usually accompanied sand injection. This is common between 148 and 156 m, and was also seen elsewhere (e.g. 126 m).
The upper 12 m of the hole are unconsolidated sediment, but below this the resistance to the bit increased dramatically and the subsequent core from level to the bottom of the hole, showed a high degree of lithification, reflected in the sonic velocities of 2 to 3 km.s−1, which record an irregular increase down the hole (Table 2). Highly cemented layers of the order of a metre thick occur at a number of levels below 140 m, and several are correlated with seismic reflectors (Table 3, Fig. 9).
The core was sampled for smear slide analysis at varying intervals depending on lithology.
Cadex was used as a mounting media and after initial problems in its application, proved to be a reasonable substitute for Canada Balsum. The slightly higher refractive index of cadex did not allow differentiation between Ca and Na plagioclase feldspar.
The smear slide analysis proved useful in determining sediment texture (sand: silt: clay ratio), mineralogy of the sand size fraction and nature of the biogenic component.
Three petrographic provinces could be recognised in the cored section:
Micritized carbonate (micarb) often occurs in large quanities, probably derived from the dissolution of foraminifera and other calcareous fossils or from erosion of marble basement rocks in southern Victoria Land. No calcareous nannoplankton were observed in the smear slides. Micarb appeared at 40 metres (s.b.) and occurred consistently to the bottom of the hole.
Coarse-grained, well rounded quartz, with occasional silica overgrowth, characteristic of Beacon Sandstone sediments were found in significant proportions at 130 metres (s.b.).
The smear slide analysis has proved to be useful for a quick and effective determination of mineralogical changes that occurred in the core. It is useful for determining the presence of diatoms and was the basis for detailed sampling for diatoms.
The exclusion of the coarse fraction during slide preparation caused a textural bias which resulted in an apparent increase in the amount of mud-size sediment.
We sampled 72 intervals from the MSSTS 1 drill core taken in western McMurdo Sound. Core recovery was 100.15 m, 43.6% of the drilled succession. Our average sample frequency of recovered sediment is 1.4 m. The size of the samples was generally small and became progressively smaller down hole as narrower diameter core barrel was utilized. Sample sizes range from 15cc to 30cc.
Most of the samples proved to be semi-lithified diamictons. To extract the Foraminifera, we originally used the procedure of soaking and boiling each Sample in hydrogen peroxide to disaggregate the sediment. As this proved to be insufficient for most of the samples, we attempted to improve break-down of the material by drying the fragments in an oven at 120°C for three hours, then placing them in kerosene to soak overnight. Following this, the samples were removed from the kerosene and boiled in water. This procedure was applied to seven of the samples known to contain Foraminifera. This also proved to be inadequate. A second chemical, dimethyl sulfoxide (DMSO), was used on one sample, 36-5, 17-19cm, on an experimental basis to determine if it would penetrate the sediment and thus facilitate disaggregation. The sediment was boiled in DMSO at 100°C for several hours. This method also did not substantially increase disaggregation of the sediment, and as the chemical is very caustic, we returned to the use of hydrogen peroxide. This time, we preceeded the boiling treatment by crushing the larger fragments of the core samples with a hammer or mortar and pestle. The crushing was first
Further processing included washing, sieving through a 63 micron standard mesh to remove clay-sized particles, followed by floatation in carbon tetrachloride to concentrate the biogenic material. Microscopic examination was then made of the floated portion. Table 7 lists the samples, the contained biogenic material, and the sub-bottom depths from which each sample was taken.
There are two foraminiferal assemblages evident in the samples we collected from the MSSTS 1 drill core. The upper fauna was found in cores 2, 10, 11, 15 and 16. It consists of twelve species, as follows: Trochammina sp., Pyrgo sp., one other species from the Miliolidae family, Fissurina sp., Rosalina globularis, Epistominella exigua, Spirillina sp., Globocassidulina subglobosa, Globocassidulina crassa, Nonion sp. (possibly Elphidium sp.), and a planktonic from the Globigerinidae family (see Table 6). The sub-bottom depths from which this fauna was extracted range from 9.72m to 32.15m. The assemblage consists of several species which are long-ranging in time, making it very difficult to determine an age for the sediments of this upper sequence.
This fauna exhibits some similarities to Pleistocene faunas from the DVDP holes 10 and 11 in Taylor Valley and also to that of the elevated marine deposits of the Cape Barne-Royds area of Ross Island (Wrenn, 1977, Ward, 1979). Rosalina globularis, Epistominella exigua (?vitrea), Globocassidulina crassa and G. subglobosa are found in all three of these sites. Species of Pyrgo, Trochammina, Fissurina, and Trifarina are also found at all three locations, though all those present in MSSTS 1 drill core have not been specifically identified to the species level. None of these taxa are particularly definitive as to time range, but the comparisons of the MSSTS 1 material with the known Pleistocene collections seen to indicate a similar age for the upper fauna of MSSTS 1.
The lower foraminiferal assemblage is also characterized by sparse faunal occurrences. The largest populations are confined to the interval from 118m to 127m sub-bottom (Cores 36 through 39), although scattered tests are found between 63m (Core 29) and 186m (Core 59). The interval from 186m to the bottom of MSSTS 1 (229m) appears to be barren of Foraminifera. Fifteen species are recognized in this lower assemblage: ?Verneuilina sp., Fissurina cf. annectens, Cassidulinoides parkerianus, C. ?porrectus, Epistominella exigua, Rosalina globularis, Elphidium Sp., Trochoelphidiella sp., Cribrononion cf. magellanicum, Globigerina quinqueloba, ?Candeina sp., Eponides tumidulus, Ehrenbergina sp., Nonionella bradii, and Anomalinoides sp. Two of these species are also present in the upper assemblage.
The small size of the lower foraminiferal assemblage and its sparse occurrences put some constraints on age determination. This fauna has strong similarities to the early and mid-Miocene assemblages from DSDP Sites 270, 272 and 273 in the Ross Sea (Leckie, Koch, D'Agostino, these in progress). The planktonic foraminiferid Globigerina quinqueloba has a New Zealand range of Otaian (early Miocene) to Recent (Jenkins, 1971). A potentially useful bioseries in the genus Trochoelphidiella Webb has been recognized in the early Miocene sequence of DSDP Stie 270 (Leckie, in progress). Continued investigations of Trochoelphidiella sp. from MSSTS 1 using the scanning electron microscope may permit better age resolution and correlation.
The preservation of the Foraminifera from MSSTS 1 is generally moderate to good. The tests have a characteristic yellowish color, differing from the clean white forms found on the floor of McMurdo Sound today. The presence of fragmented diatoms, sponge spicules, and other macrofossil debris as well as stratification of the sediments, suggests some reworking. There is no clear evidence for mixing of foraminiferal faunas of different ages. This observation, along with the quality of preservation, argues against extensive recycling of sediments. The very low abundance of Foraminifera may, in part, be explained by the small sample sizes. Oceanographic conditions
Two hundred and thirty samples (approx. 5 cc) were taken from the MSSTS core at Scott Base for fossil diatom analysis. These were treated with Hydrogen Peroxide in the U.S. Thiel Earth Laboratory at McMurdo and smear slides were made using Naphrax as a mounting media.
Fossil diatom fragments occur in at least 60% of the samples. Preservation is poor and identification difficult. No samples have been found which can provide an easy key to the stratigraphy such as occurred in DVDP 10 and DVDP 11. There is so much evidence of reworked Middle Miocene material that this author provisionally interprets the core interval from 35.43 m to 222.43 m as sediments scoured from ancient Miocene fjords during the uplift Of the Transantarctic Mountains.
So far, no Pliocene or Pleistocene diatoms have been found in the 38.43 −222.54 m interval. This suggests a Miocene age for the material even if it has been reworked. Fossil diatoms themselves indicate a Middle Miocene age with close affinities to the RISP J9 cores. No subdivision of this large interval has yet been found except there are some intervals barren of fossil material (148.63 - 167.17 m and 186.09 - 213.70 m).
The upper section 9.71 m - 21.70 m is different. Even though the majority of diatom fragments are similar to those in the lower core, non-marine diatoms occur. The analysis of DVDP 10 & 11 indicates that this flora is a Pleistocene to Early Pliocene flora which lived in terrestrial lakes, or in freshwater lakes wedged between ice shelves and the land, or in freshwater pools on ice shelf surfaces. As yet no definite date can be assigned to this upper section other than to indicate a Pleistocene - Pliocene age.
In August-September a fuller report will be available on the diatom stratigraphy of the MSSTS core. There are some intervals which may provide some control if the diatom fration can be concentrated by heavy liquid techniques.
Six lines approximately normal to the axis of McMurdo Sound were set out with flags on wooden beacons at 2 1/2 km spacing to facilitate surveys across the sound (Fig. 10). Ice breakout prevented those lines north of the Strand Moraines from extending more than 16 km east from the Victoria Land coast. It was intended to make extensive piston coring, bottom photography, bathymetric and gravity surveys. However, electronic problems with the triggering of the camera prevented any underwater photography and the piston coring was only partially successful.
Piston cores were obtained from 9 sites (Table 8). The corer, 1 m long by 47 mm in diameter, was loaded with 40 kg of lead. It was lowered on a 4 mm wire rope through a 25 cm diameter hole drilled in the sea ice by mechanical auger and triggered to free fall the last 5 m to the sea floor. Core was recovered in a plastic liner and held with a phosphorbronze cone core catcher, extended by plastic strips. Most cores obtained were less than 60 mm long and only one attempt in three produced any core at all. The reasons for non-recovery of core were not ascertained but it appears likely that when lowered rapidly the corer descends on a helical path induced by spinning due to unwinding of the hawser laid rope. In addition, there may have been core loss due to inadequate functioning of the core catcher.
Eleven piston core samples were examined. Most of the cores, (PC1-8) contain dominantly calcareous foraminiferal faunas, with several hundred well-preserved tests present. PC 9-11 contain dominantly finely agglutinated assemblages, and a lower number of tests. The preservation of calcareous tests in these three samples is very poor, indicating re-working or calcium carbonate dissolution.
Cores 4 and 5 consisted of live sponge and sponge spicule mat respectively. Core 4 had a sparse foraminiferal assemblage but species present were similar or identical to those in the other cores.
The sediment in the samples varies from very fine sand to granule and pebble size clasts. To date no sedimentologic analyses have been attempted on this material.
At all gravity and piston core sites in McMurdo Sound water depth was measured to an accuracy of 1 m with a weighted terylene line. Along the Strand profile, McMurdo Sound has an assymetric cross-section with the longer limb on the western side and a maximum water depth of 611 m occurring two thirds of the way across the sound. The Butter Point profile is similar. The Ferrar profile runs down the centre of the valley formerly occupied by the Ferrar Glacier. Water depths in the valley were found to vary between 200 and 235 m but 15 km from the present glacier snout there is an abrupt rise in the sea floor and water depth decreases to 125 m. Further out water depth increases again to 180 m, the typical depth obtained from many measurements throughout the New Harbour area. The shallows at the mouth of the Ferrar Valley are thus anomalous. They are thought to be due to moraines left by the retreating Ferrar Glacier. Similar moraines, now submerged, have been reported from elsewhere in McMurdo Sound (Northey & Sissons (1974); Wong & Christoffel, in press).
A 75 × 50 mm pole with 500 mm square crossed red plywood vanes was set up on the floating snout of Ferrar Glacier. The pole is buried about 1.5 m in the ice and the top of the pole was measured to be 0.860 m above the ice surface on 9.11.79.
Colin Fink, N.Z. Lands and Survey Department, has established three stations on the sides of Ferrar Valley to monitor the movement of the pole. The co-ordinates of the pole in November 1979 were
Co-ordinates of the three valley side stations are
Gravity was observed with a Worden gravity meter at 2 1/2 km intervals along all profiles except that at Cape Armitage (Fig. 10). All observations on the sea ice were repeated and the standard error of observation found to be 0.4 mgals. The positions of stations were determined by starting profiles at known locations and setting a course directly toward another known feature. Distances were measured by metre wheel. Precise surveys were subsequently made of the entire Strand Profile and of three beacons in the Ferrar Profile including one at the snout of the Ferrar Glacier. In all cases station positions are known to better than ± 200 m. Elevations on the sea ice are known to within 0.1 m. The total error in computing Bouguer Anomalies is less than 0.7 mgals.
Bouguer Anomalies computed for a crustal density of 2.67 gm/cc and water density of 1.00gm/cc were used to construct Figure 10, a Bouguer Anomaly map of McMurdo Sound Dry Valley region. The map includes additional data from land based surveys discussed later (Event 13). Bouguer Anomaly profiles along the lines of observation are given in Figure 11. The main feature is steep positive eastward gradient across the Victoria Land Coast previously described by Bull (1962) and Smithson (1972). Smithson attributed his results to crustal thinning under McMurdo Sound together with a +0.2 gm/cc intrusion at a depth of 4 km in basement under the Sound.
Our survey also shows a 15 mgal anomaly in the reverse sense to the main gradient and not found in the previous surveys. The anomaly has a wavelength of 5 km and is centred 10 km east of the Victoria Land Coast. Preliminary models show that it is consistent with a vertical 0.4 gm/cc density discontinuity having a throw of about 1 km and mid depth of about 1 km, the feature could be a basement fault down thrown to the east.
Several VUWAE members remained in Antarctica after drilling had been completed to participate in other field programmes, many of which were related to the MSSTS project. Part 2 is a report on these programmes and presents preliminary scientific results.
The Mt. Fleming area was revisited to complete a study of the Weller Coal Measures initiated the previous 1978-79 season. Further outcrops of the coal measures in the "cirque basin" at Mt. Fleming were measured and described in detail. These latest data complete the detailed three dimensional coverage of the outcrops which is required to determine the depositional history of the Weller Coal Measures. The new information has also helped to confirm and refine the interpretation of several features found the previous season.
In southern Victoria Land the alluvial Weller Coal Measures are deposited on the Pyramid Erosion Surface (P.E.S.) overlying the Permian Metschel Tillite. Barrett and Kyle (1975) has already shown from evidence at Mt. Fleming that the "time gap" represented by the Pyramid Erosion Surface is small. Work this year has shown that a pod comprising tillite interbedded with carbonaceous shale (Plate IX) is stratigraphically equivalent to a thin laterally extensive sandstone bed containing dispersed clasts and carbonaceous material. These three lithologies are considered facies of the Metschel Tillite. In some places the pyramid Erosion Surface has formed on the sandstone bed. In others, however, sandstone of the Metshcel Tillite appears to grade into the lowest shale lenses of the Weller Goal Measures.
At Mt. Fleming the Metschel Tillite facies are interpreted to have been deposited in glacial and proglacial environments. Small fluctuations of the ice front incorporated vegetation growing around the ice margin. The basal Weller Coal Measures were deposited immediately after the final ice retreat in a periglacial climate. The lithofacies association suggests deposition from a meandering stream system and this will be checked from analysis of the paleocurrent measurements taken from the coal measures. This will show more precisely the directions of current flow and the sinuosity of the depositing river. The paleocurrent directions from the outcrops at Mt. Fleming also will be compared with the directions from Shapeless Mt. 20 km away where the coal measures are very similar.
Three thin calcareous beds (av 100 mm) previously described by Barrett & Webb (1973) and Bradshaw (in press) were traced over a large area of Mt. Fleming this season. The trace of the outcrop delineates an area of about 10 square kilometres. Three very similar calcareous beds were also found in the same stratigraphic position at Shapeless Mtn. about 20 km away. It is inferred that the depositional environment in which these beds accumulated coexisted at both localities and that the environment was laterally continuous over 20 km.
Bradshaw (in press) has found analcime zeolite associated with the upper calcareous bed at Mt. Fleming and interpreted the analcime to have formed from evaporation. This season symmetrical ripple marks (Plate X) were found in the same bed (Bradshaws main horizon) and indicate subaqueous accumulation.
By determining whether the ripples are wave or current formed it is hoped to define precisely the depositional environment.
A point of interest last season was the finding of paleosols at Mt. Bastion and Mt. Fleming that appeared to have formed under cool temperate conditions in the Permian. This season similar paleosols were found higher in the sequence in the upper part of the Feather Conglomerate at Horseshoe Mtn. A comparison of the paleosols shows that both have a well-developed gammate structure in the greenish clay-rich upper horizon and an iron accumulation zone in the lower clay-deficient horizon.
The paleosols are interpreted to have formed under similar climates yet the nature of the flood plans on which they developed were quite different.
Five days were spent at Horseshoe Mountain, near Mt. Fleming, where geological mapping and sampling was carried out. The strata cropping out are the Feather Conglomerate (Late Permian-Early Triassic) and tile Lashly Formation (Mid-Late Triassic). (Plate XI)
The Feather Conglomerate is a corase to very coarse poorly sorted quartzose sandstone with large scale trough cross-bedding. The upper part is represented by a series of "fining-upward" cycles of medium, moderately well-sorted sandstone (Fleming Member - McKelvey et al., 1970).
The Lashly Formation is a sequence of sandstone and carbonaceous mudstone and has been divided into four members (Barrett et al., 1972); Members A, B and C appear to be complete at Horseshoe Mountain with member D occurring within the top 15 meters of the summit.
The Lashly Formation also crops out at the summit of Mount Fleming where 20–30 meters of member A is represented. Reconnaissance and a small amount of sampling of the Lashly Formation at Shapeless Mountain was all that time and weather conditions permitted. Several of the key stratigraphic horizons found at Horseshoe Mountain could be recognised at Shapeless Mountain, including the thin blue-grey muds-bone beds containing white rootlets and the silicified tree horizon.
Detailed petrological studies will be made of the sandstone samples from Horseshoe Mountain to determine mineralogical changes that may occur throughout this Triassic sequence. The relationship between sandstone texture and sedimentary structures will also be studies.
The Coombs area was visited this season to locate and examine remnants of pre-Pleistocene lodgement tills. A study of these deposits was started in 1977/78 by VUWAE 22 and this season's work was a continuation of that programme.
A major find this season was the uncovering of a fossil striated pavement at over 2800 m on Mt. Brooke. This is at least 800 m above the present ice level. This pavement, in conjunction with other evidence from Mt. Feather (Brady and McKelvey 1979) strongly suggests the East Antarctic Ice sheet in Southern Victoria Land predated the Victoria Orogeny. In other words, the mountains are being pushed up through the ice-sheet. The ice-flow direction shown by the pavement is in very close agreement with that determined from the Cenozoic tillite described from Mt. Feather.
The pre-Pleistocene tillite examined at the northeastern end of the Coombs Hills was previously considered to be a Plateau derived remnant of the so-called Sirius Tillite (Mayewski 1975). However, when taking into account the composition of the till stones and comparing these with the geological composition of the Coombs Hills it appears the till can only have been derived from a local neve field in the Convoy Range region, that was drained by an earlier phase of the then expanded Curreen Glacier.
Further Palaeontological and mineralogical investigations of the Cenozoic till are planned.
Granitic basement rocks were sampled in the Bull Pass - Lake Vida region to use for fission track investigation. The samples arrived in Melbourne at the end of February where processing of the material by Dr A. Gleadow of the Particle Tracking Laboratory, University of Melbourne was immediately commenced. The fission track technique will be employed to decipher the uplift history of the Transantarctic Mountains (i.e. the Victoria Orogeny) by determining the time when the basement reached a certain level in the earth's crust.
Moraine lobes which flank the Pearse Valley slopes of the Kukri Kills were mapped in detail. The lobes average 250 to 300 metres in length with faces approximately 25 metres high and have wind-blown hollows giving the surface hummocky relief. Surface clasts show no evidence of imbrication or elongation.
These lobes are interpreted to result from at least two phases of alpine glaciation. Detailed mapping revealed that one lobe contains features possibly formed by delayed retreat during the second phase. This could possibly be interpreted as a third alpine glacial phase.
The alpine moraines can be distinguished from Robinson's (1978) "early Taylor" moraines present in the Pearse Valley by mineralogical composition. The "early Taylor" moraines contain plutonic clasts, specifically K-feldspar granites, which are absent from the alpine moraines.
Formation of patterned ground on the alpine moraine surfaces indicates they are ice-cored and Robinson (pers. comm.) has found matrix ice within the moraines. The shape of the moraines suggests plastic deformation of the matrix ice is presently occurring.
Further investigation in the Pearse Valley is needed to relate the chrono-stratigraphy and ice-flow directions of the "Taylor" glacial expansions to the alpine glacial phases, and also to the fluctuations in levels of Lakes House and Joyce.
The present survey was intended to extend marine seismic coverage to: i) the western side of McMurdo Sound, in order to examine the nature of any faulting or other structures in the boundary zone between the Trans Antarctic Mountains and the Ross Sea: ii) to examine the continuity of the basin structure to the north side of Ross Island; iii) to extend seismic coverage northwards to link with previous work at Terra Nova Bay; iv) to obtain reconnaissance results around Beaufort and Franklin Islands and also across the sould into Granite Harbour. With the limited time available it was not possible to achieve many of our objectives. However, a moderate amount of good data was obtained in this year's survey, which will form a good basis for future work intended in this region.
Seismic operations commenced at 0530 UT, 7 February, and continued until 0600, 11 February, except for a seven hour break on 8 February to return to McMurdo station. Several piston cores were also taken by the Project S207 team during the survey, some of which coincided with downtimes of K-12 seismic system. K-12's larger compressor was damaged due to oil pressure failure before the start of surveying, and they were therefore obliged to use their backup airgun system and smaller compressor throughout the survey. This meant that maintenance downtime was much greater than would otherwise have been the case. However, the K-12 backup system in general operated reliably.
Standard operation procedure was as follows: three siesmic arrays and a magnetometer fish were trailed astern of the fantail, while the airgun was launched and towed from the portside fantail winch. The signal from one array was filtered and fed to the K-12 EPC recorder to give an immediate analog display of the seismic coverage, while a second array was fed without filtering into a FM tape recorder for later processing and playback. The third array was also directly recorded to provide a trigger signal corresponding to gun fire instant. The magnetic field was recorded in analog form on two chart recorders. Three disposable sonobuoys were launched to obtain seismic refraction data. Two worked well, and one transmitted data which can probably be reprocessed to give a usable record. A continuous PDR watch was also maintained by members of the S207 project team and the marine science technicians during seismic operations.
The approximate coordinates of end points of seismic lines, and the positions of sonobuoy drops are listed below. Deviations from straight course and breaks in seismic records along these lines Occurred due to ice conditions, equipment downtime and coring station stops.
A reasonable amount of useful seismic data, and a good bathymetric record were obtained. The Beaufort Island - Granite Harbour leg in particular gave a good seismic record. Gently dipping strata are evident and are truncated at or near the seabed by an unconformity. The unconformity is thought to be the same as that observed elsewhere in McMurdo Sound and the Ross Sea.
The Dry Valleys gravity survey was designed to compliment the Sea Ice gravity survey made earlier in the season and to fill gaps in the existing data measured by Bull (1962, 1964), Smithson (1971), Stern (1978) and Hicks, Bennett and Wendon (1980). A detailed gravity traverse was completed down Taylor Valley from Northwest Mountain to the sea, with stations at 1 to 3 km intervals. Gravity readings were also made at approximately 10 km spacings in the Lower Ferrar and Blue Valleys and on the Dailey Islands.
Gravity was measured with a Worden gravity meter relative to the Scott Base Gravity Ease for which absolute gravity is 982992.6 mgals Hatherton (1961). Precision of measurement is within 0.3 mgals. Heights of stations were determined barometrically relative to surveyed heights of trig stations and lake surfaces; heights are known to within ± 5 M. Where available the 1:50 000 USGS topographic maps which now cover most of the survey area were used. Terrain corrections for Hamner Zones B to D were estimated in the field and for zones E to M templates were used on the topographic maps. The total error in determination of Bouguer Anomalies is less than 2 mgals.
Major movements were by helicopter and the service was completely satisfactory. The necessity to use "opportunity basis" helo movements at times caused only minimal delays due to the competent scheduling of the Scott Base Deputy Leader (Ted Robinson). Work from base camps was done on foot and a small camp back-packed to Horseshoe Mt.
Event 11a camped at Mt. Fleming from December 4 to January 2 on the same site that was occupied the previous season. Horseshoe Mountain was visited by climbing from the camp up the back of the Mt. Fleming cirque to Plateau level then walking southwestwards on blue plateau ice and moraine to Horseshoe Mt, where the three party members spent a total of four cosy nights in a two man tent. The party moved to Vanda station (by helo) for the festive season after returning to Mt. Fleming camp from Horseshoe Mt., and returned again to Mt. Fleming in late December. Early in January Event 11a moved to Shapeless Mt. camping in the large north facing cirque for five days.
The weather pattern at Mt. Fleming was similar to that experienced previously in the 1978–79 season. Katabatic winds from the polar plateau and low temperatures (averaging about −14°C (@ camp level) restricted the duration of a field day to a few hours especially when working on the exposed ridges.
Winds less than 20 knots (@ camp level) were experienced for only 1/3 of the period December 4 to 22.
Weather observations were made approximately twice daily at Mt. Fleming and Shapeless Mt. These records are summarised in Appendix III.
In general no problems were experienced using a DSIR Compak SSB radio to communicate with Scott Base. Most communication problems we had appeared to originate from the Scott Base transceiver. A lithium cell was used with the Compak set at Horseshoe Mt., giving excellent service. Blowing snow at this camp caused a static electricity charge on the dipole aerial. This was sufficient to give a significant shock or a violent spark of 2-3 mm when earthed to the tent pole. Under these conditions even communication with Vanda Station was nearly impossible, and the radio was used for a minimum period of time. The aerial was disconnected to prevent damage to the radio when not in use in this situation.
The only damage, apart from breakages of scientific equipment, was the bending of one section of the aluminium ridge pole in an Italian Tent.
Event 11b would have used nearly all its allotted 6.5 hours helicopter time in being placed near Mt Brooke in the Coombs Hills and in Bull Pass
Overall the weather conditions in the Coombs Hills ranged from poor to dismal. Out of the nine days (6th to 14th) spent in the Mt. Brooke end of the Hills four were entirely lost due to gale conditions (winds in excess of 50 knots and temperatures down to −18°C). On another one and a half days conditions were at best only marginal. At the second (lower) campsite at the northern end of Coombs Hills near the Curreen Glacier conditions were considerably better. Only one day was lost, although gale conditions made another marginal. Observations of the Mt. Brooke end of the Hills made from the northeastern (Curreen Glacier) end suggested that bad weather conditions (i.e. non working) existed in the former location when workable conditions existed in the latter.
We would strongly recommend that campsites in the Coombs Hills along the Plateau edge and near the headof the Odell Glacier be avoided. On no account should parties camp on the Upper Odell Glacier. Very strong katabatic winds would appear to be common throughout the region and in the latter area would place a party at risk.
At Bull Pass the typical Dry Valley climate was relaxing and much appreciated. Summary of weather records are presented in Appendix III.
Primus problems
The primus issued with the NZARP kitchen box was not usable in the Coombs Hills. Although tested by us and apparently O.K. at Scott Base, at 2000 m the production of carbon monoxide was profuse, the indicator becoming black within minutes. The back-up stove (an Optimus from the VUWAE store) operated safely and well at all times.
Brady and McKelvey were outfitted with cold weather gear by Antarctic Division D.S.I.R. for which VUWAE paid a rental. The new D.S.I.R. issue (green) quilted jackets and the new style windproofs were much appreciated under the weather conditions encountered in the Coombs Hills. The windproof trousers do need braces, however, as they work down particularly when the pockets contain equipment, etc. Ankle tapes are also needed as it's very easy to snag a crampon spike and, and while climbing, even a projecting rock.
Every effort should be made to extend for at least one more season the search for "old" pre-Pleistocene tills and tillites, and striated pavements north of the Mawson Glacier. Particularly, this should be done in the Trinity Nunatak, Schultz Peak - Mt Armytage, and Mount Murray regions. It is appreciated that the Coombs Hills-Allan Hills area is at the limit of helicopter range for a payload of 1650 lbs. However, we feel that by adopting a much more austere (but still adequate) field ration and by pruning equipment to essentials this load for a ten day trip could be reduced to under 1000 lbs. This could be done without jeopardizing in any way the safety of the field party. Given the refueling facility at Marble Point, could not the operational range be extended so as to reach these localities at the head of and on the north side of the Mawson Glacier.
Event 11c camped at Sigrid Pond during the period December 4-13 and mapped on foot moraines in the upper and lower Pearse Valley.
Event 11c was not supplied with meteorological instruments although records of the weather conditions in Pearse were made visually and with the use of a soil thermometer. These observations were relayed to Scott Base on the morning and evening radio scheds. and are summarised in Appendix III.
Event 11c experienced excellent weather conditioning during their stay (Dec. 8 - 13) in Pearse Valley. The wind was never greater than 25 knots and temperatures were warm enough to melt surface ice of Sigrid Pond.
A Labgear radio was used and generally gave no problems in communications with Scott Base. On two separate days relay via Vanda Station was necessary due to poor radio conditions at Scott Base.
Two batteries were picked up together with a radio from the Scott Base Post Office. In the field, one battery was found to be dead even though the Post Office had given the assurance that both were fully charged. Problems could have been experienced without a spare battery if the planned field duration had been longer.
It is necessary for pre-field checks to be carried out on both the radio transmitter and spare batteries.
The supply of tent pegs at Scott Base was nonexistent when 11c was preparing to leave for the field. Makeshift pegs were prepared at Scott Base for use at the Sigrid Pond campsite where suitable rocks were known not to be available. A greater number of tent pegs and ice screws (for ice camps) should be held at Scott Base for tent pitching purposes.
(Note: Event 12 was based on USCG icebreaker "Glacier". Field notes are therefore not presented as for other Scott Base supported field events.)
Fine weather and calm seas were experienced throughout the survey. Temperatures were rather low for the time of year (min. −15°C). The sea ice had broken out from most of the Sound except on the western side. The surveys were prevented in New Harbour and Granite Harbour by very close pack ice.
Icing of the pressurised air system of the airgun, and ship generated electrical noise, were the main problems. Despite siting the compressor in the wet lab. corridor for warmth, freezing of the airline between compressor and firing board, and also at the firing board itself regularly occurred. This problem was partially overcome by running an electrical heater near the firing board. Both the seismic arrays and the magnetometer were subject to electrical noise pickup, which in the case of the magnetometer resulted in the collection of very little useful data. Apart from 60 Hz noise, intermittent noise from motor drives and other sources, and radio transmissions caused interference problems at times. However, it will be possible to remove most of this noise from the seismic data on replay of the tapes.
On Taylor Glacier 180 km of travel was completed with Snowtric toboggan 016 in the region between Finger Mountain and the vicinity of Lake Joyce. Generally travel was with a very lightly laden sledge except for the move from Camp I to Camp II where a 250 kg load was hauled.
The Briggs and Stratton motor started and ran well until a bearing in the centrifugal clutch seized near the end of projected glacier travel. A small disc to prevent direct air entry to the carburettor was lost and had to be replaced after the second day.
The tobaggan being designed to run on snow did not travel particularly well over the rough scalloped ice on the lower Taylor Glacier. On two occasions bolts were sheared in the front suspension and once the right rear axle came loose and was dragged by the track to jam against the front axle.
A gravity survey was completed from the head of the Taylor Glacier near Northwest Mountain to the sea. Travel on the glacier was by tobaggan. Walking traverses were made down the Pearse Valley and in that part of the Taylor Valley below the glacier. Camps were made on the Taylor Glacier at the head of the Pearse Valley and near Lake Joyce. From Lake Joyce the party was moved to a camp at the snout of the Howard Glacier. The party was put in on 8.12.73 and taken out on 24.12.79.
Systematic weather observations were not made. No severe storms were experienced but about three of the seventeen days in the field were spent confined to the tent due to winds exceeding an estimated 30 knots.
Morning and evening scheds were maintained with Scott Base except occasionally when the party was away from camp making surveys at the time of the 1830 sched. Communication from Scott Base was almost invariably excellent but on one occasion transmissions to Scott Base had to be relayed via Vanda.
The radio aerial was broken near one end due to it becoming embedded in glacier ice but all was recovered, temporarily repaired and returned to the Post Office.
As mentioned above various mishaps befell the toboggan.
(i) A better selection of spare parts should be provided for the toboggans. A supply of nuts, bolts and locking washers is essential.
(ii) It appears that the roller bearing in the clutch should be lubricated occasionally. This was unknown to us and should be made known to future tobogganers.
The 1979-80 Victoria University of Wellington Antarctic Expedition members would like to extend their gratitude and thanks to:
The University Grants Committee for shouldering the manor financial burden of the expedition.
The University Internal Research Committee for financial support and grants to expedition students.
Antarctic Division, DSIR, personnel for their continuous logistic, field and clerical assistance.
The U.S. National Science Foundation for providing generous air support by the US Navy VXE-6 Squadron.
The 1979-80 Scott Base staff and M.O.W. Drillers without whose help the drill project and later field events would not have been possible.
Also we wish to thank:
We are especially grateful to the Trans-Antarctic Association for grants to support the participation of Dr B.C. McKelvey and Mr H. Brady.