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Victoria University Antarctic Research Expedition Science and Logistics Reports 1980-81: VUWAE 25

B. MAIN AREAS COVERED

B. MAIN AREAS COVERED

The specific objectives were to sample rocks from two sets of red beds, regarded as overbank and lake deposits in an alluvial plain. The youngest, the Aztec siltstone is Upper Devonian in age and we sampled at reported suitably exposed outcrops. These were all at the head of the Skelton Nevee, at Portal Mt., Alligator Peak and Mt. Crean. At Portal Mt. we camped on the Nevee at the foot of the Eastern side of the slope and about 100m below the rock exposures. The site was easy to land at and reasonably sheltered on drift snow.

The Alligator Peak site to the South was up a gully immediately at the foot of the rock exposure. It provided a confined landing site and a rather confined campsite on a patch of snow on the side of a slope. Our proximity to the rocks paid dividends as even with our limited time we were able to collect a full set of very friable rocks.

The second set of red lake bed deposits were in the Terra cotta siltstone of Lower Devonian age. The best outcrops are at Mt. Kempe, Table Mt. and Knobhead.

The Mt. Kempe site at an elevation of 2,600m was on the Kempe Glacier, overlooking the Koetlitz G1. It was a magnificent site with a view to Ross I. and beyond. We could regularly see Beaufort I, 230km distant. We were about 3/4 hr walk from the rock sections up the N.B. ridge of the mountain.

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The Table Mt. site was on a small snow patch in a valley looking out to the junction of the Ferrar and Taylor Glaciers. The rocks were a 20 rain walk up a hillside and were exposed mainly under two overhangs.

The Knobhead site was in a rocky valley between Knobhead and Mt. Handsley. These rock exposures were the best and most complete of the Terra Cotta. They showed evidence of extensive burrowing and were more purple than those at Table Mt. We sampled the complete section in two different places. Our camp was in the valley, about 200m below the section. There is a large flat platform on the E. ridge level with the top of the section. It has a commanding view of the Taylor and Ferrar Glaciers and of Mt. Lister in the Royal Society Range. It would make an ideal campsite.

The site at Mt. Crean was on the south shoulder of the mountain. It was almost level with the Polar Plateau to the W. but fell away sharply to the Skelton Nevee on the East. Geologically it was in the Weller Coal Measures of Permian age. We took over the site vacated by Event K14. The Aztec red beds were on the southern buttress of the ridge, about 3/4 hr walk, where we obtained samples throughout the 100m extent of the Aztec exposure. The sun got onto the face at about 1900 hrs but owing to restraints of time and weather most of the sampling was undertaken in the morning or cloudy conditions without the sun. We looked directly down to the Portal, one of the access routes from the Skelton Nevee to the Polar Plateau.

During my second visit to Antarctica this season with Event K9, whilst awaiting the departure of the Benjamin Bowring, I was able to obtain more samples from the following areas:

Wright Valley. Samples were obtained from about 12 lamprophyre dykes outcropping on the south side of Lake Vanda. They are intruded into the granite basement and are believed to be of Ordovician age.

Miers Valley. We landed on the north side of Miers Valley, on a tableland dotted with small tarns, which at that time of year were ice-free and circled by algae. We sampled the numerous dykes which criss-crossed the region and again are believed to be of Ordovician age. Our pick up helo came earlier than scheduled, but we still managed to collect good samples from 12 sites.