Marichuela Formation

The Marichuela Formation (Formación Marichuela, N1m) is a geological formation of the Bogotá savanna, Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The formation consists of coarse to very coarse conglomerates. The Marichuela Formation dates to the Neogene period; Late Miocene to Early Pliocene epochs, and has a maximum thickness of 40 m.

Etymology
The formation was defined by Helmens and Van der Hammen in 1995 and named after the Marichuela neighbourhood of Usme. Part of the Marichuela Formation had been included in the Conos de Tunjuelo, defined by Julivert in 1961.

Lithologies
The Marichuela Formation consists of coarse to very coarse conglomerates.

Stratigraphy and depositional environment
The Marichuela Formation unconformably overlies the Cretaceous rocks of the Guadalupe Group. The age has been estimated to be Late Miocene to Early Pliocene. The depositional environment has been interpreted as alluvial fans, caused by earthquakes or heavy rains.

Outcrops
The Marichuela Formation is apart from its type locality in the Usme Synclinal, the valley of the Tunjuelo River, found in the synclinals of Neusa, Sisga and La Calera.