(Table 3) AMS radiocarbon datings of soil profiles obtained in the Nagqu area

All macroremain samples from the Nagqu area yielded negative radiocarbon ages. The atmospheric nuclear weapon tests in the 1950s and early 1960s caused a steep increase of atmospheric 14C production to nearly double the natural value in 1963, leading to 'hyper-modern' 14C contents in naturally produced organic material, thus to highly negative radiocarbon ages. Thus the radiocarbon ages of the macroremains analysed can be clearly identified as modern (after 1950).