Ayacara Formation

The Ayacara Formation is a sedimentary formation made up of interbedded sand and siltstone cropping out around Hornopirén and Ayacara Peninsula in western Los Lagos Region, Chile. Less common rocks are tuff and conglomerate. The formation dates to the Early and Middle Miocene (no earlier than 21.8–17.6 million years ago) when it deposited during a marine transgression.