This region has been re-defined to include an area from the Coolgardie Bioregion – the area between Lake Hope, Forrestiana and Mount Holland, which comprises Salmon Gum and Black Morrell woodlands on greenstone, with smaller areas of mallee and Acacia / Casuarina thicket on sandplains. The south-eastern part of Yilgarn Craton is gently undulating, with partially occluded drainage. Vegetation is mainly mallee over myrtaceous-proteaceous heaths on duplex (sand over clay) soils. "Melaleuca" shrublands characterise alluvia, and "Halosarcia" low shrublands occur on saline alluvium. A mosaic of mixed eucalypt woodlands and mallee occurs on calcareous earth plains and sandplains overlying Eocene limestone strata in the east.