arc externe

CONT: Arc insulaire [...] De la fosse vers le continent, on peut rencontrer d'abord un arc externe (arc frontal) sans volcanisme actuel ou récent, puis un arc interne à volcans actifs [...]

CONT: Groups of islands which follow more or less curved lines are called island arcs. ... Typically there is an inner arc of active volcanoes and an outer arc of nonvolcanic islands which may contain sediments of the types now found on the deep-sea floor ...