The site consists, among other things, of metamorphosed basalt lava and intrusions of basalt and gabbro derived from oceanic crust. At Tviberg you can also observe the boundary between the oceanic crust of the Solund–Stavfjord ophiolite complex and the Sunnfjord mélange, a mixture of continental and oceanic deposits. This area is important for understanding the processes involved in the formation of oceanic crust and its subsequent emplacement onto a continental margin during the Caledonian mountain-building event.
