GEOMORPHOLOGY, GEOLOGY AND PALEOHYDROLOGY OF THE BROAD ALLUVIAL VALLEYS OF THE SALT RIVER SYSTEM, WESTERN-AUSTRALIA

The Salt River System forms the connection between the saline lakes of the Yilgarn River catchment in the east and the rejuvenated Avon Rive r System in the west. Judging from the age of the deposits in the pala eochannels of the Salt River after the Darling uplift and from the del taic deposits of the river before the uplift, it appears that the rive r has been occupying this same course since the Early Tertiary. The up lift dammed the course of the river and caused the formation of large inland lakes. The inland lake at Yenyening persisted for a long time u ntil the opening of the northern outlet of the Avon. This explains the absence of sedimentary deposits from the Avon in the Perth Basin duri ng the closure time. The relatively thick sediments that fill up the p alaeochannels comprise three formations of the Salt River Group: South Caroline Clay, Yenyening Formation and Quairading Sandstone. The reco nstruction of the palaeoriver showed that the river was occupying a st eep gorge about 70 m deep with a slope of about 0.35 m km(-1).