During the Jurassic period (200 – 145 Ma) the Ligurian-Piedmontese ocean is formed by the separation of the lands. Thus the Atesina Platform and the Lombard Basin are separated. The Southern Alps become part of the northern margin of the Adria microplate, belonging to the African continent. In the western Trentino area, new carbonate platforms are formed (Corna Formation). At the same time, on the Atesina platform, the Group of Gray Limestones (Formation of Monte Zugna, Oolithic Limestone of Loppio, Rotzo Formation, Oolithic Limestone of Massone) is deposited. Made up of limestones in an environment whose depth gradually increases from the tidal plain to the open sea.
At the same time as the Group of Gray Limestones, the Formation of the Tofino settles in the Lombard Basin. Currently it emerges between the Giudicarie Line to the west and the Vedretta dei Camosci Line to the east. It consists of flint-rich limestones. Starting from the Middle Jurassic, the differences between platform and basin are smoothed out, there is a widespread collapse of the Southern Alps with the deposition of Rosso Ammonitico Veronese and Selcifero Lombardo.