Jama Formation

The Jama Formation is a Pliocene to Early Pleistocene (Montehermosan to Ensenadan in the SALMA classification) geological formation in Ecuador. The claystones and sandstones were deposited in a coastal environment. The age of the Jama Formation is constrained by 40Ar/39Ar dating of tephra beds. The formation is correlated to the Charco Azul Formation of western Panama and southeastern Costa Rica.

Subdivision
The formation is subdivided in, from top to base:
 * El Matal Member (60 m, fluvial)
 * Punta Ballena Member (lower shoreface)
 * Punta Pasa Borracho Member (20 m, marine)

Fossil content
The formation has provided bivalve, gastropod and scaphopod fossils.