Pisco Formation

Pisco Formation
Stratigraphic range: Mid Miocene-Early Pleistocene (Colloncuran-Uquian) ~15–2 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Lithology and sediments of the Pisco Formation across its allomembers
Type	Geological formation
Unit of	Pisco Basin
Overlies	Chilcatay & Caballas Formations
Thickness	640 m (2,100 ft)
Lithology
Primary	Tuffaceous sandstone, diatomaceous siltstone
Other	Conglomerate, dolomite
Location
Coordinates	15°42′S 74°30′W / 15.7°S 74.5°W / -15.7; -74.5
Approximate paleocoordinates	15°48′S 73°48′W / 15.8°S 73.8°W / -15.8; -73.8
Region	Arequipa & Ica Regions
Country	Peru
Extent	From Pisco to Yauca
Type section
Named for	Pisco
class=notpageimage| Outcrops of the formation in Peru

The Pisco Formation is a geologic formation located in Peru, on the southern coastal desert of Ica and Arequipa. The approximately 640 metres (2,100 ft) thick formation was deposited in the Pisco Basin, spanning an age from the Middle Miocene up to the Early Pleistocene, roughly from 15 to 2 Ma. The tuffaceous sandstones, diatomaceous siltstones, conglomerates and dolomites were deposited in a lagoonal to near-shore environment, in bays similar to other Pacific South American formations as the Bahía Inglesa and Coquimbo Formations of Chile.

Several specialists consider the Pisco Formation one of the most important Lagerstätten,^[1][2] based on the large amount of exceptionally preserved marine fossils, including sharks (most notably megalodon), penguins, whales, dolphins, birds, marine crocodiles and aquatic giant sloths.

Famous fossils found in these layers include the giant raptorial sperm whale Livyatan,^[3] the aquatic sloth Thalassocnus,^[4] the sperm whale Acrophyseter, and the walrus-like dolphin Odobenocetops.^[5]