The calcarenite, shale, siltstone, marl and conglomerate formation dates to the Tertiary period and has a maximum thickness of 2,200 metres (7,200 ft).

The Iguape Formation is 1,103 to 2,200 metres (3,619 to 7,218 ft) thick,[1] and consists of bioclastic calcarenites and calcirudites, containing bryozoa, echinoids, corals, foraminifera, fragmented shells, and algae remains.

They are interbedded with grey-greenish clays, siltstones, marls and variegated grey fine-to-medium grained conglomerates.

The depositional environment is thought to be a marine carbonate platform, influenced by the arrival of alluvial clastics in the most proximal areas.

Biostratigraphic data from planktonic foraminifera, calcareous nannofossils and palynomorphs indicate a Tertiary age.