History of a Foreland Basin
Mountain building halts and it begins to erode back down to a peneplain. Meanwhile the sediment eroded from the mountain has largely filled in the Basin
and a substantial meandering river system builds its way toward the foreland. This progressive building of environments across the Basin
is called Progradation
Also observe that by this time the depositional environments have evolved to a long system. Deposition of the submarine fan has all but stopped; the Basin
to the west is just too shallow to provide the kinds of slopes turbidity currents require. Instead meandering river and shelf environments dominate the Basin
(compare with Stage III
), and will finish filling in the basin.