| Soncco Formation | |
| Type: | Geological formation |
| Age: | Late Eocene-Early Oligocene |
| Period: | Oligocene |
| Prilithology: | Conglomerate, sandstone |
| Otherlithology: | Coal, lacustrine limestone |
| Namedfor: | Soncco |
| Region: | Puno & Cusco Regions |
| Coordinates: | -13.3367°N -71.7411°W |
| Unitof: | San Jerónimo Group |
| Subunits: | C, D & E Members |
| Underlies: | Punacancha Fm., Tinajani Fm. |
| Overlies: | K'ayra Formation |
| Thickness: | 1600m (5,200feet) |
| Map: | Blakey 035Ma - COL.jpg |
The Soncco Formation is a Late Eocene to Early Oligocene geologic formation in southern Peru. The base of the formation at the contact with the K'ayra Formation is dated using fission track analysis at 43 Ma and the top, the contact with the Punacancha Formation, at 30 Ma.[1] In other places the Tinajani Formation overlies the Soncco Formation.[2] The formation has a thickness of 1600m (5,200feet).[3]
The formation was first dated to the Cretaceous, and fossil ornithopod tracks had been reported.[4] Over 9,000 fossil tracks are said to be found within this formation. As the formation has been dated to the Paleogene, the tracks could not be attributed to dinosaurs.[1]