This is arguably the most damaged ecosystem in the state. This is a low-lying coastal plain, mainly covered with Tuart-Banksia woodlands. It is dominated by Banksia or Tuart on sandy soils, "Allocasuarina obesa" on outwash plains, and paperbark in numerous former swampy areas. In the east, the plain rises to duricrusted Mesozoic sediments dominated by Jarrah woodland. Three phases of marine sand dune development provide relief. The outwash plains, once dominated by Allocasuarina obesa-marri woodlands and "Melaleuca" shrublands, are extensive only in the southern part of the region.