Agua de la Piedra Formation

Agua de la Piedra Formation
Stratigraphic range: Late Oligocene (Deseadan) ~26–23 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Geological formation
Unit of	Malargüe Group
Sub-units	"Rodados Lustrosos" level
Underlies	alluvium
Overlies	Pircala-Coihueco Formation
Thickness	37 metres (121 ft) (tuffs)
Lithology
Primary	Tuff
Other	Paleosols
Location
Coordinates	36°36′S 69°42′W / 36.6°S 69.7°W / -36.6; -69.7
Approximate paleocoordinates	37°48′S 62°54′W / 37.8°S 62.9°W / -37.8; -62.9
Region	southern Mendoza Province
Country	Argentina
Extent	southernmost Precordillera northernmost Neuquén Basin
Type section
Named by	Gorroño et al.
Location	Quebrada Fiera, Malargüe
Year defined	1979
Coordinates	36°33′13.3″S 69°42′3.5″W / 36.553694°S 69.700972°W / -36.553694; -69.700972
Region	Mendoza Province
Country	Argentina
Thickness at type section	37 metres (121 ft) (tuffs)
Agua de la Piedra Formation (Argentina)

The Agua de la Piedra Formation (FAP, Spanish names include Estratos de Agua de la Piedra and Complejo Volcano-sedimentario del Terciario inferior)^[1] is a Late Oligocene (Deseadan in the SALMA classification) geologic formation of the Malargüe Group that crops out in the southernmost Precordillera and northernmost Neuquén Basin in southern Mendoza Province, Argentina.^[2]

The strictly terrestrial tuffs and paleosols of the formation, geologically belonging to Patagonia, have provided a wealth of mammal fossils of various groups at Quebrada Fiera, including Mendozahippus fierensis, Pyrotherium, Coniopternium and Fieratherium. Terror birds reminiscent of the terror bird Andrewsornis and indeterminate remains of the phorusrhacid family have found in conjunction with the mammals.