Figure 6

Core Monteith-A sedimentary facies relative to sea level and valley-wide cross section extrapolated from CPTs collected in transect. (a) The Bacon age-depth plot for core Monteith-A is plotted, relative to facies designation, against the Holocene sea-level envelope for the Southern Australian coast (blue)¹⁵. The inception of the Murray estuary, and commencement of deposition of the central basin sequence, is synchronous with the onset of marine flooding at this location. Calibrated ¹⁴C ages are denoted by black points, with the approximate timing of sea-level stabilisation to the present-day level shown as 3,500 yr BP^4,44,45,46. (b) A valley-wide cross section at Monteith (rkm 104; transect M-M’ given in Fig. 1c,d) developed from SBT analysis of thirteen CPTs reveals that the central basin (Unit 5) is uninterrupted across the whole width of the valley. The underlying single-thread fluvial (Unit 3) and braided fluvial (Unit 2) facies are interrupted only by limestone and bedrock outcrops at the extent of the valley. Dashed lines indicate uncertainty with question marks denoting uncertainty at depth.