The Blacklane Brook profile, first published in 1964, has been re-examined and given firm dating in the light of the archaeological and fossil tree-line interest that the profile has generated. A much fuller record of the open vegetation of Flandrian I is presented, and many new pollen types for the site are indicated. The recession phase noted in 1964 is found in this profile also and is dated to begin ca. 7760 BP. It is thus placed well within the Mesolithic cultural period. The resolution of the pollen diagram and the difficulties of interpretation of upland sites do not make it possible to make firm statements about the location of the tree-line at different periods.