Geology and preliminary dating of the hominid-bearing sedimentary fill of the Sima de los Huesos Chamber, Cueva Mayor of the Sierra de Atapuerca, Burgos, Spain - Bischoff, J.; Fitzpatrick, J.A.; Leon, L.; Arsuaga, J.L.; Falgueres, Christophe; Bahain, J.-J.; Bullen, T. (Journal of Human Evolution, 1997)