The Moyjil site, south-west Victoria, Australia: stratigraphic and geomorphic context

Abstract

Shelly deposits at Moyjil (Point Ritchie, Warrnambool), Victoria, together with ages determined from a variety of techniques, have long excited interest in the possibility of a preserved early human influence in far south-eastern Australia. This paper presents a detailed analysis of the stratigraphy of the host Bridgewater Formation (Pleistocene) at Moyjil and provides the context to the shelly deposits, evidence of fire and geochronological sampling. We have identified five superposed calcarenite–palaeosol units in the Bridgewater Formation, together with two prominent erosional surfaces that may have hosted intensive human activity. Part of the sequence is overlain by the Tower Hill Tuff, previously dated as 35 ka. Coastal marine erosion during the Last Interglacial highstand created a horizontal surface on which deposits of stones and shells subsequently accumulated. Parts of the erosional surface and some of the stones are blackened, perhaps by fire. The main shell deposit was formed by probable mass flow, and additional shelly remains are dispersed in the calcareous sand that buried the surface.

The Moyjil site, south-west Victoria, Australia: excavation of a Last Interglacial charcoal and and burnt stone feature — is it a hearth?

“…A rhizomorph cast with a diameter of around 3 cm was uncovered in the western part of Square C (Figures 8,11,12). This rhizomorph appears to have formed in situ and possibly represents a post-depositional intrusion into CBS1 by a root from a shrub growing around 2 m above the developing upper calcrete layer at least 50,000 years ago (see Carey et al 2018). Figure 11: CBS1 during excavation of upper level of feature with large fragments of charcoal surrounded by charcoal-stained sediments (Square C) and darkened (dark-grey to grey) stones (Square D) exposed at the end of XU4 (Square C) and XU12 (Square D).…”

“…GEOMORPHIC AND CHRONOLOGICAL SETTING CBS1 is located near the top of the stepped cliff face of Moyjil on the west side of the mouth of the Hopkins River, Warrnambool, western Victoria (Figures 1 and 2). Detailed geological and geomorphic investigation of the headland by Sherwood et al (1994) and most recently by Carey et al (2018) and Sherwood et al (2018a) indicates a complex sequence of loose and cemented aeolian dune sands dating to the Pleistocene and spanning at least the past 400,000 years. Of immediate concern for CBS1 are two calcrete layers (carbonate-cemented calcarenite sands) found across the upper sections of the headland: an 'upper calcrete' (unit Q2cs) up to 0.5 m thick and a 'lower calcrete' (unit Rcp) up to 1.25 m thick ( Figure 3).…”

“…The upper surface of the lower calcrete layer (unit R) has been stripped back by recent erosion to create a 2-5 m wide pavement or bench designated Ground surface alpha (Gsa) by Carey et al (2018) (Figures 2 and 3). CBS1 is embedded within the lower 15 cm of sands resting directly on the upper surface (Gsa) of the lower calcrete layer at an elevation of c.8 m above sea level ( Figure 4).…”

“…CBS1 is embedded within the lower 15 cm of sands resting directly on the upper surface (Gsa) of the lower calcrete layer at an elevation of c.8 m above sea level ( Figure 4). According to Carey et al (2018), the basal 20-30 cm of calcarenite sands forming the matrix of CBS1 gained their reddishbrown colour as a result of oxidation and development of a reddish clay coating on grains through weathering and pedogenesis. Such oxidation is considered to have taken place elsewhere and not to represent in situ weathering and pedogenesis.…”

“…. Broader stratigraphic and OSL dating interpretation of underlying sediments suggests strongly that unit Q sands, and by extension CBS1, dates to the Last Interglacial (~120,000 years ago) (see Carey et al 2018;Sherwood et al 2018a for details).…”