Biostratigraphy and chronostratigraphy of the Early and Late Weichselian substages in Denmark are discussed and a more complete terminology than previously used is proposed. The size variation in Weichselian birch pollen assemblages was compared with subrecent samples. Mean pollen size and variance of the parent species were determined and the proportions of the parent species were calculated. The results confirm earlier conclusions. Percentage frequency‐curves for Betula nana and B. pubescens in Late Weichselian pollen diagrams were calculate