Qualla: Ipubi Formation

Ipubi Formation: Introduction

Thu, 16 Apr 2026 00:00:00 GMT

Photo credit Carlos E. Fabin, Osvaldo J. Correia Filho, Márcio L. Alencar, José A. Barbosa, Tiago S. De Miranda, Virgínio H. Neumann, Igor F. Gomes, Felipe R. De Santana, CC BY 4.0. The layer is only about fifteen meters thick, pressed between two thicker rock formations that get all the attention. Geologists call the Ipubi Formation the middle child of the Santana Group - less famous than the fossil-rich Crato beneath it and less dramatic than the Romualdo above, which captured sharks and pterosaurs in stone. But what Ipubi records is something stranger than any single creature. Over a few million years in the Early Cretaceous, an ancient lake in what is now northeastern Brazil dried and flooded and dried again, each cycle leaving behind shale and gypsum like pages in a notebook. The Atlantic Ocean had not yet opened here. When it did, Ipubi was the threshold.

Read more: Ipubi Formation on Qualla

Image: Carlos E. Fabin, Osvaldo J. Correia Filho, Márcio L. Alencar, José A. Barbosa, Tiago S. De Miranda, Virgínio H. Neumann, Igor F. Gomes, Felipe R. De Santana | CC BY 4.0

Ipubi Formation: Rift in a Young World

Thu, 16 Apr 2026 00:00:00 GMT

Photo credit Fabin et al., 2018, CC BY 4.0. To understand Ipubi, you have to picture a Brazil that no longer exists. Around 120 million years ago, South America was still pulling away from Africa, and the rift between them ran diagonally across what would become the Borborema Province. The Araripe Basin formed as part of t...

Read more: Ipubi Formation on Qualla