ABSTRACT

Age determinations by the C¹⁴ method have been made on the matrix and enclosed fauna of a Quaternary calcareous concretion from the shelf southeast of Cape Campbell, New Zealand. The results show that the concretion must have formed within 19,500 years, and probably within 7500 years. It appears to have grown in a calcareo-argillaceous sediment containing an abundant molluscan fauna.

The classification of concretions, and the terminology applied to them, are discussed in this paper. The three categories recognised by Richardson (1921) are retained, but it is suggested that the terms "contemporaneous," "penecontemporaneous," and "subsequent" should be replaced by "syngenetic," "diagenetic," and "epigenetic." The Cape Campbell concretion is considered to be diagenetic.

C¹⁴ determinations on other Quaternary concretions should throw further light on the absolute rate of concretion-forming processes.