Figure 2. Valley of Lakes Paleogene and Neogene key sections dated by the K-Ar and 40Ar-39 Ar methods (from west to east). Symbols: 1 - Eocene basalt, 2 - Oligocene basalt, 3 - Miocene basalt, 4 - Shand-Gol Formation, redbed clay, 5 - Loo Formation, marl, 6 - clay, 7 - sand, 8 - gravelstone, 9 - cobblestone, 10 - weathered basalt, 11 - mammalian finds, 12 - Formation, 13 - Locality.