The Soncco Formation is a

Late Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "d ...

to Early Oligocene geologic

formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondary ...

in southern

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...

. 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.Carlotto, 2016, p.522 In other places the Tinajani Formation overlies the Soncco Formation.La Torre et al., 2004, p.116 The formation has a thickness of .Cusco.gob, 2015, p.120

Misattributed ornithopod tracks

The formation was first dated to the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

, and fossil ornithopod tracks had been reported.Weishampel, et al. (2004). "Dinosaur distribution." Pp. 517-607. Over 9,000 fossil tracks are said to be found within this formation. As the formation has been dated to the

Paleogene The Paleogene ( ; also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period million years ago (Mya) to the beginning of ...

, the tracks could not be attributed to dinosaurs.

References

Bibliography

* * * * {{ISBN, 0-520-24209-2 Geologic formations of Peru Paleogene Peru Eocene Series of South America Oligocene Series of South America Tinguirirican Divisaderan Mustersan Rupelian Stage Priabonian Stage Conglomerate formations Coal formations Limestone formations Sandstone formations Lacustrine deposits Fossiliferous stratigraphic units of South America Paleontology in Peru Geography of Cusco Region Geography of Puno Region