Western Asgard Range

The Plio/Pleistocene deposits listed in Table 19.6 are lateral moraines associated either with the Taylor Glacier (i.e., Taylor II, III, IV) or with alpine glaciers (i.e., Alpine A, B, C, D). Both types of moraines are composed of boulders and cobbles in a matrix of sand and gravel. The boulders are composed of dolerite (-68%), 

The Miocene deposits consist of till and associated colluvium most of which are older than 11.4 Ma. Both types of deposits are composed of gravelly sand, gravelly mud, or sandy gravel and their thickness ranges from less than 1.0 to about 3.0 m. The clasts are composed of dolerite, sandstone, and granite in about the same proportions as in the Plio/Pleistocene drift of Arena Valley. Only the clasts in the Arena till and the Altar till contain faceted and striated clasts. In addition, the Brawhm till and the Arena till were deposited on striated bedrock. 

The history of glaciation of southern Victoria Land as we know it relies heavily on isotopic dating of Cenozoic 

In some cases, the volcanic ash in Arena valley was mixed into lobate achalanche deposits and into Quartermain I till. Ash also occurs in thin layers within colluvium and was deposited on the desert pavement of the Monastery colluvium in the central 

Arena valley. The undisturbed ash is more than 99% pure, whereas the reworked deposits contain more than 50% of non-volcanic contaminants. The ash appears to be unweathered and contains less than 5% of secondary clay indicating that the climate in this area has remained cold and dry since the middle Miocene (Marchant et al. 1993a). 

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Selected crystals of sanidine and shards of volcanic glass were dated by the Ar/ Ar method at the Berkeley Geochronology Center. In addition, exposure ages were determined by means of in-situ produced cosmogenic radionuclides (Brown et al. 1991 Brook et al. 1993). The "Ar/ Ar dates derived from volcanic ash in Arena Valley and from sites in the western Asgard Range are listed in Appendix 19.9.1. 

The volcanic ash in the western Asgard Range occnrs in sand wedges that formed by contraction of... 

In spite of the present harsh climatic conditions of the western Asgard Range, or perhaps because of them, endolithic plants are presently growing in the sandstone exposed in the Linnaeus Terrace on the north-facing (i.e., sunny) slope of the Asgard Range in Fig. 19.22... 

Fig. 19.22 The valleys of the western Asgard Range contain Range as weU as in Arena Valley during the Miocene and PUo/ deposits of till and colluvium of Miocene age. Although these Pleistocene (Marchant et al. 1993a, b). Excerpt from the topo-...

Table 19.7 Stratigraphy of the glacial deposits of Miocene age in the western Asgard Range (Fig. 19.22) of southern Victoria Land (Marchant 1993b)...

Marchant DR, Denton GH, Sugden DE, Swisher CC III (1993b) Miocene glacial stratigraphy and landscape evolution of the western Asgard Range, Antarctica. Geogr Ann 75A(4) 303-330... 

Fig. 3.5 The western end of Wright Valley in southern Victoria Land is framed by the Olympus Range in the north and the Asgard Range in the south. Ice from the East Antarctic ice sheet of the polar plateau enters the valley via the Airdevronsix icefaU and forms the Wright Upper Glacier. The Labyrinth at its base was carved by meltwater streams flowing under pressure at the base of a glacier that once flUed the Wright Valley. Lake Vanda is peren-...

Fig. 10.5 The Wright Valley in southern Victoria Land slopes west, away from the coast, and contains the Onyx River which flows from Lake Brownwoith at the foot of the Wright Lower Glacier to Lake Vanda at the western end of the valley (Fig. 3.5). The Asgard Range south of Wright Valley supports several valley glaciers which were named by Professor R.L. Nichols after...

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