Figure 10    VML dating of stone artifacts in the drylands of western USA. (A) A varnished grinding stone from Chili of northern New Mexico, where numerous Anasazi pottery shards were found. (B) Rock varnish from the grinding stone in (A) displays a latest Holocene layering sequence LU-1 (WH2), suggesting a varnish-based minimum age of 900-1100 YBP for abandonment of this occupation site by the Anasazi Indians. (C) A varnished primary stone core from Ocotillo of southern California (collected by Jay von Werlhof, Desert Museum of Imperial Valley College). (D) Rock varnish from the primary core in (C) displays a latest Pleistocene layering sequence LU-1/LU-2 (WP0), suggesting a varnish-based minimum age of 12,500 YBP for the making of this stone artifact by the Paleo-Indians. A green line in (B) identifies the position of probe line profile for Ba seen in Fig. 6E. Camera cap in (A) for scale; arrows in (A) and (C) point to sites where varnish-filled microbasins were cored with a minidrill (4 mm in diameter) for dating.