The bogs of S. E. Groningen are part of the great peat-marshes extending from S. E. Drente as far as N.W. Germany inclusive. So far as the territory of Westerwolde is concerned, people have begun digging off very early. According to the map by Krayenhoff in 1816 nearly the whole peat-marsh westward from the line Blijham—Termaarsch had already been reclaimed, only a few parts still being covered with the original peat-layer (cf. map, fig. 1). The digging off east of the above line commences at the beginning of the 19th century on the borderland of Groningen and Drente. Borings were performed in three places and the samples pollenanalytically and stratigraphically examined.