Phanerozoic strata of the Bonaparte Basin in the north-western part are mantled by Quaternary marine sediments supporting Samphire - "Sporobolus" grasslands and mangal, and by red earth plains and black soil plains with an open savanna of high grasses. Outcrops of Devonian limestone karst in the west support tree steppe and vine thicket. Plateaux and abrupt ranges of Proterozoic sandstone, known as the Victoria Plateau, occur in the south and east, and are partially mantled by skeletal sandy soils with low tree savannas and hummock grasslands. In the south east there are limited areas of gently undulating terrain on a variety of sedimentary rocks supporting low Snappy Gum over hummock grasslands and also of gently sloping floodplains supporting "Melaleuca minutifolia" low woodland over annual sorghums.