Published online by Cambridge University Press: 18 July 2016
The C14 dates given below are a continuation of the work presented in our previous list (RIKEN III), and have been obtained by counting CO2 at ca. 2 atm pressure in a 2.7 L stainless steel counter. Results obtained mainly during 1967 are described.
Shell samples were treated with 1% HCl to remove the outer 10%. Calcareous deposits on the surface, when observed, were removed by mechanical means.
Dates were calculated on the basis of the C14 half-life of 5568 yr and 95% NBS oxalic acid as modern standard. No correction was applied even for fresh water shell samples.