Naar de zandzuigerij aan de Zomerweg te Bergum

The author has collected a great number of crystalline and sedimentary erratics of Fennoskandian origin in a sandwinning-locality near Bergum, Friesland. Remarkable is the sporadic occurrence of rapakivi -granite from the Åland Isles, common to very common in other localities. The absence of sulphide of iron in alle limestones from this locality and on the other hand the abundance of pyrite in nodules. Peatballs and mudballs. A description is given of the problems, the possibilities and the solution of the problems