Fremouw Formation

Fremouw Formation Stratigraphic range: Upper Permian - Upper Triassic
The Beardmore Glacier, which overlies parts of the Fremouw Formation.
Type	Geological formation
Unit of	Victoria Group
Sub-units	Lower, Middle, Upper
Underlies	Falla Formation
Overlies	Buckley Formation
Thickness	up to 1,000 metres (3,300 ft)
Lithology
Primary	Sandstone, siltstone, mudstone
Location
Region	Transantarctic Mountains of Antarctica

The Fremouw Formation is a Triassic-age rock formation in the Transantarctic Mountains of Antarctica. Fossils of prehistoric reptiles and amphibians have been found in the formation. Fossilized trees have also been found. The formation's beds were deposited along the banks of rivers and on floodplains. During the Triassic, the area would have been a riparian forest at 70–75°S latitude.

The Fremouw Formation is Triassic in age, although the oldest rocks date back to the latest Permian. Much of the formation is quartzose sandstone that was deposited in stream beds. It overlies the Permian Buckley Formation, which consists of coal and Glossopteris fossils. The formation is informally divided into lower, middle, and upper units. Most fossils are found in the Lower Fremouw Formation. Here, bones are preserved in fine grained siltstones and mudstones, coarse grained channel sandstones, and conglomerates.

The first tetrapod or land-living vertebrate from Antarctica was found in the Fremouw Formation and described in 1968. It was represented by a small bone fragment that is probably part of the left mandible of a temnospondyl amphibian. The bone was found the previous year by a researcher from Ohio State University who was studying the geology of the Transantarctic Mountains. The animal was later named Austrobrachyops jenseni. After its discovery, paleontological expeditions were launched to the area around the Beardmore Glacier to uncover more fossils. Since then, fragmentary remains of temnospondyls, therapsids, and archosauriform reptiles have all been found in the formation. These fossils are found around the Shackleton and Beardmore glaciers in places such as Gordon Valley and Fremouw Peak.