|Several clearly defined areas around Ouyen and to the east of Lake Tyrrell contain dry saline lake beds with prominent north east - south west ridges and occasional lunettes. East-west dunes occur on the ridges and plains. Landscapes are susceptible to increased salinity on the plains and to erosion on the dunes, sandy ridges, and lunettes which are composed mainly of red or grey clays.
North east - south west ridges about 2 – 10 km long, 1 km across and less than 5 m high have received scant attention being confused with strandline ridges. They occur in parts of the Raak, Tyrell and Noora depressions at variable density. They are prominent near some groundwater depressions in the Raak and Tyrrell basins. Soil profiles have been seen only in a few road and rail cuttings. The core of the ridges observed was a mottled red-grey clay, suggesting early Pleistocene weathering. These clays are overlain by calcareous loamy sandy layers of the Woorinen Formation and are frequently fashioned into east - west dunes.