Extensive and broad zones of outwash sands surround the prominent strike ridges of the Grampian Ranges. Examples include outwash slopes along the eastern fringe of the Grampians Ranges, for example, the Pomonal area, western Black Range and Fyans Creek Valley.
These depositional landscapes are dominated by landforms including alluvial fans, sand plains and tributaries of major drainage networks within and surrounding the ranges (e.g. Mount William Creek, Wannon River, and Glenelg River). Outwash slopes of sandsheets have maximum gradients of 5% that tend to level out towards alluvial flats and drainage lines below the ranges. Relief is generally 30 m or less (Ollier & Joyce 1986) over long gentle slopes with the number of depositional layers and depth of these deposits varied. Terraces and floodplains are found along valleys within the confines of the Grampians Ranges (Hills 1936).
Streams are unidirectional flowing away from the prominent strike ridges of the Grampians and Black ranges, often converging as tributaries into significant waterways of the catchment as creeks and rivers of floodplains and alluvial plains. Lake Belfield in the Fyans Creek Valley is an example of a dam that has harnessed the significant volumes of water shed by the ranges and slopes into this significant water supply. | |