The first terp excavations
The Association played an important role in financing the early excavations in, for instance, De Wierhuizen (1916-17), Godlinze (1919), Hatsum (1021-1923), Ezinge (1923-1934) and Leens (1939). In Ezinge, Van Giffen uncovered the posts and walls of longhouses, which made him famous.
In the 1940s, he shifted his activities to the Roman camp of Valkenburg (in Zuid-Holland). He convinced the board that this was actually a terp, and was financed by the Association of Terp Research!