The site of Kocabas is located in the Denizli Basin, in western Anatolia, 400 km southwest of Ankara, 360 km south of Istanbul, 200 km east-southeast of Izmir and 150 km northwest of Antalya. The Denizli Basin depression, at the junction of the Buyuk Menderes and Gediz grabens, which began to form at the beginning of the Miocene, was filled in around the edges, along fault lines, by significant travertine formations, some of which are still active today. The age of the Kocabas travertines, which yielded the Kocabas Homo erectus skullcap, was evaluated by thermoluminescence at 828,000 years, by electron spin resonance (ESR) at 1,110,000 years and by the Al-26/Be-10 cosmogenic nuclide method to more than 1.22 Ma and less than 1.5 Ma, a date which has been confirmed by magnetostratigraphy and biochronology. (C) 2014 Elsevier Masson SAS. All rights reserved.