Beacon Supergroup

The Beacon Supergroup is a geological formation exposed in Antarctica and deposited from the Devonian to the Triassic (400 to 250 million years ago). The unit was originally described as either a formation or sandstone, and upgraded to group and supergroup as time passed. It contains a sandy member known as the Beacon heights orthoquartzite.

Named after Beacon Heights. First named 1907, type section described in 1963. Originally dubbed a formation, with scope left (and later used) to expand to group, then supergroup, as better mapped and understood.Beacon Dome at the head of Griffith Glacier is named after the Beacon Supergroup.

also southern Victoria Land, Ross desert.

The series is over 1 km thick in places, and extends for over 1,000 miles.

The beds are almost flat lying, dipping at about 3° to the north; many are interleaved with dolerite sills.

The location of the formation in a cold, desert environment, and the lack of nutrients or soil (due to the purity of the sandstone) has led to the beacon sandstone being considered the closest analogue on Earth to Martian conditions, therefore many studies have been performed on life's survival there, mainly focusing on the lichen communities that form the modern inhabitants.

The unit is a "Fine grained, arkosic quartz sandstone". It is composed of shales, coals, conglomerates, and in places the occasional thin limestone bed.

Originally divided into 3 subunits, further refined into five facies, listed below from oldest to youngest:

Basal. Grades into Junction sandstone. Variable thickness; (0-5/17/80 m), overlies pre-Devonian plutonic rocks, of igneous and metamorphic nature, with over 30 m erosional relief. Contains igneous and metamorphic clasts.

Poorly sorted at base, influxes of coarser material. Coarseness is laterally variable - pebbles in places, sands in others, at same horizons. Planar beds, trough cross-bedding, flaser bedding, mud-drapes on some ripples; U-shaped burrows & escape structures; fining up cycles topped by desiccation cracks in places.

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