Jama Formation

The Jama Formation is a Pliocene to Early Pleistocene (Montehermosan to Ensenadan in the SALMA classification) geologic formation in Ecuador. The claystones and sandstones were deposited in an coastal environment. The age of the Jama Formation is constrained by 40Ar/39Ar dating of tephra beds.[1] The formation is correlated to the Charco Azul Formation of western Panama and southeastern Costa Rica.[2]

Jama Formation
Stratigraphic range: Pliocene-Early Pleistocene
~5.3–0.8 Ma
TypeGeological formation
PrimaryClaystone, sandstone
Coordinates0°12′S 80°18′W / 0.2°S 80.3°W / -0.2; -80.3Coordinates: 0°12′S 80°18′W / 0.2°S 80.3°W / -0.2; -80.3
Approximate paleocoordinates0°18′S 79°54′W / 0.3°S 79.9°W / -0.3; -79.9
RegionManabí Province
Country Ecuador
Type section
Named forJama
Jama Formation is located in Ecuador
Jama Formation
Jama Formation (Ecuador)


The formation is subdivided in, from top to base:

  • El Matal Member (60 metres (200 ft), fluvial)
  • Punta Ballena Member (lower shoreface)
  • Punta Pasa Borracho Member (20 metres (66 ft), marine)

Fossil contentEdit

The formation has provided bivalve, gastropod and scaphopod fossils.

See alsoEdit


Further readingEdit

  • G. Cantalamessa, C. Di Celma, and L. Ragaini. 2005. Sequence stratigraphy of the Punta Ballena Member of the Jama Formation (Early Pleistocene, Ecuador): insights from integrated sedimentologic, taphonomic and paleoecologic analysis of molluscan shell concentrations. Palaeogeography, Palaeoclimatology, Palaeoecology 216:1-25
  • H. A. Pilsbry and A.A. Olsson. 1941. A Pliocene fauna from Western Ecuador. Proceedings of the Natural Sciences of Philadelphia 93:1-79