Flandrian Environmental History of the Isle of Mull, Scotland

Abstract

SUMMARYFlandrian percentage pollen diagrams are presented from three sites in western and northern Mull, Inner Hebrides, Scotland, and these data are augmented by pollen concentration evidence from one of the sites. In general terms, the pattern of vegetational development is broadly similar to that found in a previous study in the uplands of south-central Mull. However, differences in detail are apparent in the vegetational history of the northern and western parts of the island, particularly in the representation oi Empctrwn,Jutuperus and Betula pollen in the early Flandrian deposits, and in the frequencies of Alnus and Quercus in the mid-and late-Flandnan pollen records. These pollen-stratigraphic contrasts between the three sites, and between these profiles and those from the more sheltered south-central parts of the island can be attributed partly to differences in pollen recruitment processes and partly to variations in degree of exposure to prevailing winds.

Flandrian Environmental History of the Isle of Mull, Scotland

“…By contrast, the reduced concentration of pollen and spores in zone C is a reflection of rapidly increased sedimentation rates during the middle Flandrian. Significantly, a very similar record was obtained from Beinn Reudle, the only other site on Mull from which pollen concentration data are available (Lowe & Walker, 1986b). The close correspondence between the trends in the curves for pollen concentration in these two sites suggests that the biostratigraphic records reflect primarily the influence of regional rather than local site factors.…”

“…The pollen stratigraphy described above constitutes the most detailed Flandrian record from the seven sites recently investigated on the Isle of Mull. Although useful insights were gained into Flandrian vegetational changes on Mull from the pollen sites in Glen More , and at Mishnish and Beinn Reudle (Lowe & Walker, 1986b), a combination of poor stratigraphic resolution in parts of the successions, particularly in the early Flandrian sediments, and apparently low rates of peat accumulation in the upper levels of the profiles, produced an incomplete and somewhat uneven picture of Flandrian vegetational history. The most detailed sequence had previously been obtained from Loch an t-Suidhe on the Ross of Mull (Lowe & Walker, 1986b), but at that site stratigraphic resolution of the early and middle Flandrian was not as clear as in the Gribun profile and, moreover, the highly thixotropic muds on the present lake bed made sampling impossible in the upper levels of the sediment column.…”

“…In general, these shortcomings are not manifest in the Gribun profile due principally to the maintenance of a relatively rapid rate of sedimentation during much of the Flandrian stage. Although no dates were obtained from Gribun, an estimate of the rate of sediment accumulation can be obtained using radiocarbon ages on comparable biostratigraphic horizons at other sites in the Hebrides and western Scotland (see Lowe & Walker, 1986b). The age/depth curve (Fig.…”

“…On the wider scale, the high degree of stratigraphic resolution in the Gribun profile and the relative scarcity of detailed pollen diagrams from the islands of the southern Inner Hebrides and adjacent areas of the Scottish mainland, make Gribun a strong candidate for the Flandrian type site for the central stretch of the west coast of Scotland. Lowe & Walker, 1986b) Local pollen assemblage zones, Gribun…”

“…An important additional feature of the site at Gribun is the lack of an extensive catchment area, and this combined with the absence of streams flowing into the basin means that many of the problems surrounding pollen recruitment are unlikely to be encountered. In particular, the difficulty of interpretation of fossil pollen records in which both airborne and stream-borne components are combined (Lowe & Walker, 1986b) should not arise at Gribun.…”