This region is bounded to the north and east by Hercynian massifs (Vendée, part of Armorica to the north and the Massif Central to the east). To the far south the basin is bounded by the thrust front of the Pyrenees. The Aquitaine region itself falls naturally into two halves, divided by the valley of the River Garonne To the west of the Garonne is a low lying area, the Landes. To the east of the Garonne there are bands of Jurassic, Cretaceous and Paleogene rocks in successive belts away from the southwestern part of the Massif Central. This area is dissected by a series of differentially incised meandering rivers. The coast, to the north of the Gironde estuary is low lying, dominated by saltmarshes, but to the south is a dune coast, the Landes coast.