Often these rocks show evidence of deposition in an unstable setting, such as evidence of turbidity flows or submarine landslides. This sort of deposit is known as flysch . Such rocks are typical of a continental rise or trench setting. Accompanying these rocks are often submarine volcanic rocks, pillow lavas . The rocks of the foreland are typically shallow-water sedimentary rocks typical of a continental shelf, which become thinner toward the interior of the continent.
Igneous rocks are uncommon.
As the mountain belt rises, great thicknesses of sandstone and conglomerate are deposited on its flanks and frequently bury much of the foreland. These rocks are typically shallow-water or terrestrial, often red in color, and are called molasse deposits. The stable interior of the continent will often be covered with thin layers of shallow-water or terrestrial sedimentary rocks. This thinly-mantled region is the platform The Shield Areas where ancient crystalline rocks are exposed over wide areas are called shields . Every continent has at least one shield.