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Pollen diagrams, 14C‐datings, and peat stratigraphy are presented from 3 sites in the Forradal sub‐oceanic area in Nord‐Trøndelag, a moorland complex of flat and sloping fens and blanket bogs lying 400–500 m above sea‐level, ca. 40 km E of the Trondheimsfjord. The vegetational and climatic history during the last 8500 years is described, together with a survey of present‐day conditions. The origin of the blanket‐bog areas is shown to agree generally, in both time and mode of genesis, with similar bog types in Scotland and N England. Dates are given for the expansion of both alder and spruce, the latter occurring more than 1000 years later than in SE Norway. The possible role of provenance formation and Roman Iron Age amelioration of the climate is discussed in this connection. The course of the alder pollen curve indicates a drier and probably colder type of climate at ca. 3000–2400 B.C.

Pollen analysis, 14C datings and peat stratigraphy from blanket mires overlying two of the six drumlins in the Momyr area NW of the Trondheimsfjord in Sør‐Trøndelag county are presented in order to trace the peat development and vegetational history. 14C datings of the mineral soil/peat transition in 9 of the II profiles indicate that peat formation started about 7,800 years ago on the drumlin plateaux which at that time had a vegetation of scattered birch trees. From the plateaux the peat formation spread slowly down the slopes. Eventually, the mire surface bore a cover of pines which disappeared about 4,900 years ago, at the same time as peat formation commenced at the foot of the drumlins. This was probably a result of a change in the water table and onset of erosion in the already existing peat on the drumlin plateaux. During a period of about 1,000 years this new peat buried a dense birch vegetation existing at the lower part of the drumlins. Peat growth then spread upslope, and the drumlins' overall blanket of peat was completed well before the Subatlantic chronozone.