FIGURE 2. The excavated sediment section at Mamontovaya Kurya on the southern bank of the Usa river.
From the following article:
Human presence in the European Arctic nearly 40,000 years ago
Pavel Pavlov, John Inge Svendsen and Svein Indrelid
Nature 413, 64-67(6 September 2001)
doi:10.1038/35092552
The artefacts and bones were uncovered from the river channel deposits near the base of the exposure. Radiocarbon and optically stimulated luminescence (OSL) dates from the various layers are indicated (Table 2). We note that the radiocarbon dates are given in 14C years BP, whereas the OSL dates are in principal calendar years before the present. m.a.s.l., metres above sea level.