The Hiló Formation (Spanish: Formación Hiló, Kih) is a geological formation of the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The predominantly shale formation dates to the Middle Cretaceous period; Late Albian to Early Cenomanian epochs and has a measured thickness at its type section of 470 metres (1,540 ft). The fossiliferous formation has provided a great abundance of ammonites and other marine species.

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Hiló Formation
Stratigraphic range: Late Albian-Early Cenomanian ~102–98 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Geological formation
Unit of	Villeta Group
Underlies	Simijaca Formation
Overlies	Capotes Formation
Thickness	more than 470 metres (1,540 ft)
Lithology
Primary	Shale
Other	Sandstone, limestone, siltstone
Location
Coordinates	4°47′28″N 74°30′49″W
Region	Altiplano Cundiboyacense Eastern Ranges, Andes
Country	Colombia
Type section
Named for	Caserío Boquerón de Hiló
Named by	Hubach
Location	Apulo-Anapoima
Year defined	1931
Coordinates	4°47′28″N 74°30′49″W
Approximate paleocoordinates	0.6°N 45.3°W / 0.6; -45.3
Region	Cundinamarca, Tolima
Country	Colombia
Thickness at type section	470 m (1,540 ft)
Paleogeography of Northern South America 105 Ma, by Ron Blakey

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The formation was defined and named in 1931 by Hubach after the Caserío Boquerón de Hiló in Anapoima.^[1]

Fossils of Actinoceramus munsoni, Actinoceramus aff. subsulcatiformis, Beudanticeras cf. rebouli, Desmoceras latidorsatum, Eubrancoceras cf. aegoceratoides, Exogyra aff. texana, Goodhallites aguilerae, Inoceramus anglicus, Inoceramus cf. cadottensis, Inoceramus aff. dunveganensis, Inoceramus aff. etheridgei, Inoceramus cf. ewaldi, Inoceramus aff. irenensis, Inoceramus prefragilis, Inoceramus cf. richensis, Lyelliceras pseudolyelli, Mojsisovicsia evansi, Mortoniceras arietiforme, Neocomiceramus neocomiensis, Neoharpoceras hugardianum, Oxytropidoceras intermedium, Oxytropidoceras karsteni, Oxytropidoceras laraense, Oxytropidoceras multicostatum, Oxytropidoceras nodosum, Oxytropidoceras peruvianum, ?Oxytropidoceras robustum, Oxytropidoceras venezolanum, Prolyelliceras gevreyi, Prolyelliceras prorsocurvatum, Puzio media, Tegoceras mosense, Acompsoceras sp., ?Bositra sp., Camptonectes sp., Entolium sp., Hamites sp., Hysteroceras sp., Mariella sp., Ostrea sp., Phelopteria sp., and ?Syncyclonema sp. have been found in the Hiló Formation.^{[4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]}

Type locality of the Hiló Formation to the west of the Bogotá savanna

The Hiló Formation is apart from its type locality along the road from Apulo to Anapoima, found just east of Viotá, Cundinamarca,^[26] and in the department of Tolima.^{[4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]} West of Guayabal de Síquima, the formation is offset by the Vianí Fault.^[27]

Geology of the Eastern Hills

Geology of the Ocetá Páramo

Geology of the Altiplano Cundiboyacense