Santo Domingo Formation

Santo Domingo Formation () is a mainly marine Miocene sedimentary formation located in south–central Chile. The formation was defined by R. Martínez Pardo and Mario Pino in 1979 and named after the roadcut locality they studied about southeast of Valdivia. Sediments of the formation accumulated in Valdivia and Osorno–Llanquihue Basin.
The formations overlies basement consisting of metamorphic and igneous rocks; the Bahía Mansa Metamorphic Complex and Cretaceous granitoids respectively. In parts, it further overlies the coal–bearing Pupunahue–Catamutún Formation. The sedimentary facies of the Santo Domingo Formation are composed of sandstone, siltstone and mudstone and smaller amounts of conglomerate. The formation underlies Pliocene and Quaternary sediments.
Fossil content.
Some of the trace fossils that can be found in Santo Domingo formation are "Zoophycos" isp., "Chondrites" isp., "Phycoshiphon" isp., "Ophiomorpha" isp. "Thalassinoides" isp., "Asterosoma" isp. and "Terebellina" isp.
The benthic foraminifera found in Santo Domingo Formation are broadly similar to those found in other Chilean sedimentary formations of the Neogene like Navidad Formation of Central Chile, Ranquil Formation of Arauco Province and Lacui Formation of Chiloé Island. 
 The most common formaineral species of Santo Domingo Formation are "Hansenisca altiformis", "Rectuvigerina transversa" and "Sphaeroidina bulloides".