The abundance of Glossopteris and Mesosaurus fossils in the underlying Huab Formation are characteristic of the Gondwanan correlation across present-day South America, Africa, Antarctica and Australia.

In the lower half of this mainly pelitic succession, intercalations of dark brown, very often concretionary calcareous layers up to 1 metre (3.3 ft) thick, occur.

[5] The basal beds grade into a 20 metres (66 ft) thick succession of silty to fine-grained, and eventually medium- to coarse grained, sandstone.

[5] The white tuff layers within the Gai-As Formation contain very well-preserved former glass shards, now mainly replaced by barite, are rich in potassium feldspar and have a porcelain-like appearance.

The occurrence of flaser bedding, oscillation ripples and hummocky cross-stratification in silty intercalations indicates that the sediment, surface must have been above the storm wave base.

Fossiliferous stratiform carbonates (10 to 15 centimetres (3.9 to 5.9 in) thick) with molluscs of the Terraia altissima type are transitional to the sand-flat facies which is characterised by sandy, flat and lenticular deposits and occasionally contain abundant root marks.

[11] Due to increased subsidence in the central Paraná Basin, thicknesses of the correlative units are considerably greater than that of the Gai-As Formation, attaining a maximum of 1,200 metres (3,900 ft).