The Valle Alto Formation ( es, Formación Valle Alto, Jva) is a geological formation of the

Central Ranges Central Ranges (code CER) is an Australian bioregion, with an area of 101,640.44 square kilometres (39,244 sq mi) spreading across two states and one territory: South Australia, Western Australia, and the Northern Territory.Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...

n Andes. The formation is composed of

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especial ...

s, sandstones and conglomerates and dates to the Late Jurassic period.

Ammonite Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...

s and fossil flora have been found in the Valle Alto Formation.

Etymology

The formation was described and named in 1977 by González et al. after Hacienda Valle Alto, San Félix, Caldas.Moreno Sánchez et al., 2007Mojica, 1984, p.132

Lithologies

The Valle Alto Formation is composed of

s, sandstones and conglomerates.Isagen, 2009, p.9

Stratigraphy, age and depositional environment

The Valle Alto Formation, part of the Quebradagrande Complex, is not defined as a proper formation, rather as a collection of rocks of different

facies In geology, a facies ( , ; same pronunciation and spelling in the plural) is a body of rock with specified characteristics, which can be any observable attribute of rocks (such as their overall appearance, composition, or condition of formatio ...

origin segmented by tectonic forces of the Central Ranges. The Valle Alto Formation has been deposited as the result of marine incursions from the proto-Caribbean into Colombia, preceding the larger-scale

transgression Transgression may refer to: Legal, religious and social *Sin, a violation of God's Ten Commandments or other elements of God's moral law *Crime, legal transgression, usually created by a violation of social or economic boundary **In civil law ju ...

of the Cretaceous.Mojica & Kammer, 1995, p.170

Fossil content

Fossils of '' Piazopteris branneri'', '' Cladophlebis sp.'', '' Classopollis sp.'', '' Ctenozamites sp.'', '' Desmiophyllum sp.'', '' Gleichenites sp.'', '' Nilssoniopteris sp.'', '' Otozamites sp.'', '' Pachypteris sp.'', '' Ptilophyllum sp.'', '' Rhabdoderas sp.'', '' Sagenopteris sp.'', '' Sandlingites sp.'', '' Sphenopteris sp.'', '' Substeuroceras sp.'', '' Trigonia sp.'', and '' Zamites sp.'' have been found in the Valle Alto Formation.Mojica, 1984, pp.131-132Valle Alto Formation
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...

.org

Outcrops

The Valle Alto Formation is found near its

type locality Type locality may refer to: * Type locality (biology) * Type locality (geology) See also * Local (disambiguation) * Locality (disambiguation) {{disambiguation ...

in the Central Ranges of the Colombian Andes, around Pácora and Salamina.

Notes

References

Bibliography

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Maps

* {{Paleontology in Colombia, state=expanded Geologic formations of Colombia Jurassic System of South America Jurassic Colombia Tithonian Stage Fossiliferous stratigraphic units of South America Paleontology in Colombia Sandstone formations Shale formations Shallow marine deposits Formations