MID‐FLANDRIAN CHANGES IN VEGETATION ON MAINLAND ORKNEY

S ummary The presence of birch‐hazel scrub with a rich ground flora of tall herbs and ferns in the mid‐Flandrian on Mainland, Orkney, suggested by Moar (1969), is supported, but no evidence was obtained for Pinus, Quercus, Alnus or other major forest trees as indigenous species. Evidence from lake muds and intertidal peat in the region of the Bay of Skaill suggests an increase in onshore wind speeds with the formation of the Bay of Skail and the beginning of sand‐blow c. 5000 B.P. The birch‐hazel scrub declined at this time and the remaining tall herb and fern vegetation was replaced by pasture within c. 200 years under the influence of neolithic man and his grazing animals. At c. 3400 B.P. a combination of increased oceanicity of climate and high grazing pressure appear to have led to the initiation of blanket peat formation on the hills. A contribution to the interpretation of 14 C dates derived from marly sediments is included.