Lateglacial and early Flandrian environmental history of the Isle of Mull, Inner Hebrides, Scotland

Abstract

Pollen-stratigraphic data, supported by lithological, geochemical and radiocarbon evidence are described from two Late Devensian Lateglacial sites on the Isle of Mull, Inner Hebrides, Scotland. The data suggest that, following the wastage of the Late Devensian ice sheet some time prior to 13,000 BP, an open grass- and sedge-dominated landscape was colonised first by juniper scrub and subsequently byEmpetrumheaths. Tree birch development was limited principally, it would seem, by exposure to strong westerly winds, although some scattered birch woodland did become established in more sheltered localities. The thermal maximum of the Lateglacial Interstadial appears to have occurred fromc.13,000 to 12,000 BP after which climate began to deteriorate as the atmospheric Polar Front migrated southwards. The harsh climatic conditions of the Loch Lomond Stadial, the full effects of which were experienced afterc.10,700 BP, led to the break-up of the Interstadial vegetation cover, the development of an ice cap and several smaller cirque and valley glaciers in the hills of south-central Mull, and the establishment of a periglacial regime throughout the island. Byc.10,200 BP, however, climatic amelioration was underway once more, the Loch Lomond Advance glaciers had wasted completely, and a plant succession was initiated which led to the replacement of tundra vegetation communities byEmpetrumheath, juniper scrub and eventually hazel-birch woodland within the space ofc.1500 years.