Extended Data Fig. 3: Stratigraphy and artefacts of the Sembungan excavations.

a, Map of the Sembungan terrace, showing the lithology of the terrace and the location of the terrace rise in relation to the Solo River. The bottom-right inset shows the locations of the excavations I, II and V. b, A profile of the terrace along the A–B transect from A (marked by a red dashed line), showing the location of the sand quarry excavations in relation to the river. c, The west baulk of excavation I (marked on the inset in A), showing the stratigraphic layers and location of the stone artefact concentration (red dashed line at the base of the section). Layer J, very coarse sand; layer I, brown silt; layer H, cross-bedded coarse pebbly sand; layer G, lenses of siltstone; layer F, disturbed; layer E, massive siltstone; layer D, caliche palaeosol. d–i, Stone artefacts excavated in situ from Sembungan. d, Obsidian flake. e, Chert flake with unifacial retouching to the ventral surface across the proximal end, removing the point of force application. f, Chalcedony flake. g, h, Chalcedony centripetal cores. i, Quartz crystal cluster. Scale bars, 30 mm. j, A stone tool in situ from the Sembungan excavation V. k, Excavation I (inset in a). l, Excavation II (inset in a).