The formation of upper Paleozoic (Viséan to Sakmarian-Artinskian) Euramerican cyclothems, which resulted from base-level fluctuations of up to 100 m, commonly are attributed to large-scale waxing and waning of Gondwanan glaciers. However, evaluation of the geographic and chronostratigraphic distribution of Gondwana deposits reveals that glaciation was not the primary cause of base-level changes of that magnitude.Gondwana strata contain three non-overlapping glacial successions. Glacial I (Frasnian to possibly Tournaisian) and Glacial II (Namurian to lowermost Westphalian) rocks were deposited by alpine glaciers. Water sequestered by these glaciers was insufficient to account for the base-level changes. In contrast, Upper Carboniferous (Stephanian) to Lower Permian (Sakmarian-Artinskian) Glacial III rocks were widespread and indicate deposition by ice sheets that may have covered a total area of between 17.9 and 22.6 × 10 6 km 2 . Complete ablation of a single ice sheet of this size would produce eustatic changes of ~100 m. However, multiple ice sheets were likely present, which would have resulted in considerably smaller fluctuations in sea level during Glacial III deposition.The argument that Glacial I and II deposits were originally comparable in extent to those of Glacial III, but were eroded during the advance of Glacial III ice-sheets, is untenable. Weathered granite profiles on the pre-Glacial III unconformity occur scattered over a 1200-km length of the central Transantarctic Mountains. The profiles indicate prolonged subaerial exposure and, thus, an absence of ice cover. These and non-glacial successions in Gondwana constrain the size of ice sheets before Glacial III deposition and imply that glaciation prior to Glacial Episode III was not the primary cause of base-level changes linked to upper Paleozoic Euramerican cyclothems.

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The Permian-Triassic Transantarctic basin, which occupied the Panthalassan margin of the East Antarctic craton, including the present Transantarctic and Ellsworth Mountains, evolved above a mid-Paleozoic passive continental margin basement through the following stages: (1) Carboniferous/Permian extension, (2) late Early Permian back-arc basin, (3) Late Permian and Triassic foreland basin, and (4) Jurassic extension and tholeiitic volcanism. A mid-Paleozoic (Devonian) wedge of coastal-to-shallow marine quartzose sandstone developed on the eroded roots of the Late Cambrian-Early Ordovician Ross orogen. A lacuna in EastAntarctica during the Carboniferous was followed by the inception of Gondwanan deposition in a wide Carboniferous/Permian extensional basin. Volcanic detritus at the base of the late Early Permian post-glacial marine(?) shale and sandstone sequence in the Ellsworth Mountains is the first sign of a volcanic arc and subduction along the Panthalassan margin. A similar but much thinner non-volcaniclastic sequence accumulated in the Transantarctic Mountains. The introduction of abundant volcanic detritus to the cratonic side of the basin and a 180° paleocurrent reversal in the Late Permian in the Beardmore Glacier area are the earliest indicators of tectonism along the outer margin of the basin and the inception of a foreland basin that accumulated thick Late Permian and Triassic braided stream deposits of mixed volcanic and cratonic provenance. The Permian sequences in the Ellsworth and Pensacola Mountains were folded in the Triassic. The foreland basin was succeeded in the Early Jurassic by extension and initial silicic and then tholeiitic volcanism that led to the breakup of Gondwanaland.

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