Preliminary statement on an error in British Museum radiocarbon dates

Abstract

A  systematic  error has  been  identified in  radiocarbon measurements run in  the British  Museum  laboratory  between  approximately  mid  1980 and the end of 1984, when  all  dating was  halted for a  number of months. The measurements  potentially affected  have  numbers between about BM- 1700 and BM-2315,  and correspond roughly to date  lists XV to XIX  pub- lished  in  Radiocarbon.  The  error  is systematic,  giving  dates  that  are  too young by varying  amounts:  some  may have  been  underestimated  by 200- 300 years, whilst others  may be little affected. BM dates issued during this period should be used with caution. Dates obtained since mid  1985 are not subject to this  error as  evidenced by  repeated radiocarbon measurements of dendrochronologically-dated wood (see  for example  BM-2432, date list XX,  forthcoming). A  comprehensive  set  of experiments  to  clarify and quantify the  dis- crepancy is continuing. When sufficient  data are available a  full account of the problem  will be published. Submitters of a series of samples during the period in question will also  be notified individually.