Alluvial sediments:

The sediments of the Beacon Supergroup in north Victoria Land occur as scattered outcrops exposed along cliff faces and valley walls, that have been cut by glaciers. The Permian sediments (recognised from the presence of the Glossopteris flora) rest on the flat-lying sub-Beacon surface that cuts a basement of metasedimentary and plutonic rocks.

The Takrouna Formation proposed by Dow and Neall (1974) for the sediments of north Victoria Land is from this seasons field work divided into two facies (Walker, 1982).

Facies Association 1 which outcrops in the Alamein Range, Morozumi Range and Helliwell Hills is characterised by variation in type, scale and grain size of sedimentary structures. Medium scale trough-x-bedding and ripple lamination are the most common bedforms. Mudstone lenses, planar-x-bedding, scour fill and coal measures (including coal seams, green siltstones and fining upwards sandstones) are also found. Coarse to fine grained ratios vary within sections and between outcrops and it is evident that a variable paleohydraulic regime operated during the deposition of this facies. The trough and planar-x-bedding and ripple laminated units are considered to be deposits reflecting the varied flow conditions associated with the different water level stages of flood episodes. The different scales of the same sedimentary structures reflects the varying intensity of those floods. The fine grained units including the coal measures are most probably in channel facies that were deposited when a channel became separated by the processes of channel avulsion and migration from the main flow of water. Channel cross-sections, low paleocurrent variability and sequence of sedimentary structures suggest that the rivers that deposited facies 1 had high width to depth ratios and were of low sinuosity and due to an apparent variable climatic regime could expect a variable discharge.

Facies Association 2 is exposed in the Moawhanga Never Gair Mesa, Neall Massif, Jupiter Amphitheatre (Morozumi Range) and is in marked contrast with Facies Association 1. It is dominated by multi-storey "sheet-like" sandstone bodies comprised almost entirely of medium to large scale trough and planar-x-bedding with individual sandstone bodies separated either by erosion surfaces or mudstone drapes. Facies Association 2 is considered to have been deposited by braided rivers with high width to depth ratio channels. Individual sandstone bodies probably represent discrete flood events which transported large quantities of sand by the processes of dune and transverse bar migration. Flood events were relatively frequent and allowed no time for overbank deposits to develop.

Paleocurrents for Facies Association 1 show that it was deposited on a paleoslope dipping towards the northeast and that Facies Association 2 was deposited on a paleoslope dipping west (Fig. 8).

It is possible that Facies Association 1 represents the deposits of rivers that flowed over a flat low gradient flood plain from the area of the retreating Permian ice cap that was centred in north Victoria Land at this time (Barrett et al., 1972). This depositional episode ended when uplift of mountains to the east reversed and increased the gradient of the paleoslope resulting in a new paleohydraulic regime that determined the depositional character of Facies Association 2.

Glacial beds:

An early Permian (?) tillite sequence is exposed on the western side of the Lanterman Range, north of the Orr Glacier (McKelvey, 1982). The tillite is faulted against the metamorphic rocks of the Wilson Group and is tightly folded. The following description is from McKelvey and Walker (1982).

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The glacial beds are of acid plutonic and metasedimentary provenance and are exposed on two spurs about 2 kilometres apart. On the northern spur the oldest exposed strata consist of at least 70 metres of poorly sorted lensoidal or channel-fill outwash conglomerates, pebbly sandstones and diamictites associated with laminated or cross-bedded coarse sandstones. The coarser rock types are most common at the top and bottom of this interval. A dark mudstone and shale unit containing interbeds of thin sandstone, lensoidal conglomerate and a fine diamictite overlies. This unit thickens eastwards to at least 150 metres and changes rapidly in fades to a monotonous mudstone sequence containing in its uppermost 80 metres thin laterally persistent graded and laminated turbidites sometimes with erosional bases and containing infraformational sandstone clasts. No dropstones are present. More than 100 metres of coarse outwash strata similar to those at the base of the section overlie.

On the southern spur a similar coarse sandstone sequence with lensoidal conglomerates and pebbly sandstones at the base overlies more than 150 metres of fissile or massive mudstones alternating with very coarse tillite sheets and lenses. Most of the mudstone and shale horizons contain sparsely scattered dropstones.

The contact between the folded glacigene sequence in the Lanterman Range and the widespread Permian fluvial Takrouna Formation of northern Victoria Land has not been observed. Coarse metasediment breccias up to 50 metres thick and associated sometimes with minor petromict conglomerate lenses frequently mantle the pre-Permian basement complex beneath the Takrouna Formation. No definite glacial features have been observed in these breccias.