| Chagres Formation | |
| Type: | Formation |
| Age: | Tortonian-Messinian (Clarendonian-Hemphillian) ~ |
| Period: | Messinian |
| Prilithology: | Sandstone |
| Otherlithology: | Siltstone |
| Namedfor: | Chagres River |
| Namedby: | MacDonald |
| Year Ts: | 1919 |
| Region: | Colón Province |
| Coordinates: | 9.2°N -80.3°W |
| Paleocoordinates: | 9°N -79.4°W |
| Subunits: | Río Indio & Toro Limestone Members |
| Underlies: | alluvium |
| Overlies: | Gatún Formation |
| Thickness: | uncertain |
| Extent: | Panama Basin |
The Chagres Formation (Tc)[1] is a geologic formation in the Colón Province of central Panama. The sandstones and siltstones were deposited in a shallow marine environment and preserve fossils dating back to the Middle to Late Miocene (Tortonian to Messinian, Clarendonian to Hemphillian in the NALMA classification) period.
The Chagres Formation is exposed in the northern part of the Panama Canal Zone. The formation overlies and partly overlaps the Gatún Formation. The outcrop area lies entirely west of the Panama Canal, extending from the Canal Zone southwestward along the Caribbean coast, about 45km (28miles) southwest of Colón. Calcareous strata at the base of the formation throughout most of the outcrop area in the Canal Zone constitute the Toro limestone member.[2]
The name Chagres Sandstone was proposed by MacDonald in 1919 for the sandstone forming the hills that overlook the coast from Toro Point to the mouth of the Chagres River. The sandstone is so massive that estimates of thickness are uncertain.[2]
Various fossils have been found in the Chagres Formation:[3]