Sedimentary rocks of Triassic and Jurassic age occur along the margin of the polar plateau from northern Victoria Land south to the Central Transantarctic Mountains. These fluvial and lacustrine Mesozoic sediments were deposited in two separate basins. A foreland basin, related to the folding and thrusting along the subducting Panthalassan Ocean margin in the region of the present central Transantarctic Mountains led to the deposition of the Triassic and Jurassic vertebrate bearing beds.

Figure 1: Generalized section for the Beardmore area showing stratigraphic position of the Mesozoic vertebrate faunas.

The Fremouw and Falla Formations (figure 1), which are up to 1,000 meters thick, comprise the Triassic of the Central Transantarctic Mountains. The Fremouw Formation has been informally divided into lower, middle and upper members. Fluvial sandstones, siltstones and mudstones of the lower Fremouw have produced the diverse Early Triassic vertebrate faunas.

Figure 2: Map showing the location of Mt. Kirkpatrick in the Transantarctic Mountains of Antarctica.

The most complete Jurassic sequence in Antarctica is in the Beardmore Glacier region. The Hanson Formation (figure 1), exposed at several localities on the higher peaks in the area, has yielded the Early Jurassic dinosaur fauna on Mt. Kirkpatrick at an elevation of over 4,000 meters and only 600 km from the Geographic South Pole (figure 2). Although the unit is predominantly silicic tuff, the vertebrates occur within a fluvial interbed of tuffaceous siltstone.