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Victoria University Antarctic Research Expedition Science and Logistics Reports 1978-79: VUWAE 23

West Beacon

West Beacon

Sampling at West Beacon was much more rapid. Our camp on the northeast ridge was almost half way up the section, and a minimum of time was spent in travelling to the sites. We benefited considerably by a third person in the party. Two people orienting and collecting the samples can slmost keep up with one driller.

The weather was better and although there was some snow on the rocks near the summit, it was easily cleared.

The slopes containing the chosen section faced north and northeast, enabling sampling to be carried out during the normal day. Sun compass orientations were obtained on a large proportion of samples.

The effect of these factors is reflected in the fact that it took 7 days to sample an equivalent length of section that took 14days at Mt Bastion.

We started sampling near the bottom of the section, at the New Mountain Sandstone - Altar Mountain Formation boundary in the Devonian - the exposures below this were very scattered beneath scree and it was difficult to tell whether they were in place.

Sampling was straightforward up and through the Arena Sandstone to the very prominent Beacon Heights Orthoquartzite (BHO) boundary. The rock was rather friable near the contact with dolerite sill, presumably due to baking. Some cores were taken through the 150 m thick dolerite sill. The section was then continued further around to the North and more directly up to the main peak. The BHO - Aztec Siltstone contact was a prominent erosion surface. The Aztec siltstone was characterised by hard layers of dark green siltstone which gave good cores.

The Weller Coal Measures (Permian) comprised the topmost part of the section to the summit dolerite cap rock. It was fairly coarse and extensively cross-bedded, but had no coal beds here - very similar to the lower Weller at Mt Bastion. The sampling overlap between here and Mt Bastion should provide a useful check on the reliability of the paleomagnetic measurements.

During the coring of the last few samples, the motor was behaving erractically and had considerably reduced power. With the day remaining after finishing the Beacon Heights section, the motor was decarbonised and the spark plug checked. In addition the samples were packed for transport.