The Tristel Formation is a stratigraphic formation of the northern-central Alps, deposited between the late Barremian and the early Aptian of the Early Cretaceous.

It consists of thickly banked limestones, marls and shales.

[1] It is the lowest formation of the Bündnerschiefer and belongs to the Rhenodanubic Group.

[2] Outcrops can be found in the Engadin window, the Tauern window, the Rechnitz window [de], and many localities of the Penninic realm of the eastern and western Alps.

[3] The type locality is the area around the Naafkopf (47°03′39″N 9°36′25″E / 47.060767°N 9.607067°E / 47.060767; 9.607067) in the border region of Austria, Liechtenstein and Switzerland.