The Santiago Formation is a Sandbian to Katian geologic formation of central Bolivia. The formation comprises gray quartzitic siltstones.

The formation has provided the following fossils:

• Bistramia sp.
• Lingula sp.
• Orthoceras sp.

• List of fossiliferous stratigraphic units in Bolivia

• R. Suárez Soruco. 1976. El sistema ordovícico en Bolivia. Revista Tecnica YPF Bolivia 5(2):111-123