The Santa Teresa Formation (Spanish: Formación Santa Teresa, Tist, Pgst) is a geological formation of the western Eastern Ranges of the Colombian Andes, west of the , and the southern Middle Magdalena Valley. The formation spreads across the western part of Cundinamarca and the northern portion of Tolima. The formation consists of grey claystones intercalated by orange quartz siltstones and sandstones of small to conglomeratic grain size. The thickness at its type section has been measured to be 118 metres (387 ft) and a maximum thickness of 150 metres (490 ft) suggested.