We determined Sr, Nd and Pb isotopic compositions and major- and trace-element compositions of soil samples recovered from three soil profiles developed on relatively young pyroclastic deposits, less than 10,000 years old, of the Mount Cameroon volcano. The time elapsed since then is short compared with the half-lives of Rb, Sm, U and Th, suggesting that radioactive decay can be neglected. We therefore assumed that (i) these polyphase soils developed on isotopically homogenous substrates and (ii) any isotopic variation within such profiles cannot be due to selective dissolution of primary minerals with isotopic compositions different from that of bulk bedrock. Any Sr, Nd or Pb isotopic variation would therefore record an allochtonous input occurring either in a solid or dissolved state.