In this and the following chapter, the correlation techniques applied in NW Europe (particularly in the North Sea Basin) are summarized, emphasizing their relative applicability (Fig. 8) and the history of their use. The latter aspect (pre-1978) was summarized in more detail by Curry et al. (1978, pp. 12-16). More general aspects of Tertiary biostratigraphy were discussed in some detail by Lourens et al. (2004a), Luterbacher et al. (2004), Hilgen et al. (2012) and Vandenberghe (2012).