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Immediately W of the islands of Uist in the Outer Hebrides is a wide, low-gradient submarine shelf on which glacifluvial deposits of Devensian age and calcareous sand accumulated. Following moulding by Devensian ice, the Lateglacial landscape of the littoral zone of the Uists became a series of low-lying bedrock ridges and basins. The analysis of sub-tidal organic deposits has shown that in the early Holocene this landscape supported water bodies, marshes and a vegetation mosaic of Betula-Corylus woodland and Calluna vulgaris-herbaceous taxa open ground. The submergence of this littoral area during the Holocene Marine Transgression, together with wave action typical of the position on the Atlantic margin, led to the transfer onshore of submarine shelf deposits, so creating machair (sand plain) landscapes. This brought about vegetational changes, eventually creating calcareous grasslands. The timing of these events was asynchronous, being location- and site-specific due to variations in the configuration of the littoral zone. Although the date of the initial transfer of sand is unknown, evidence from the sub-tidal deposits indicates that a major incursion of sand, in North Uist, occurred c. 7600 BP (8450–8340 cal BP). The same source also suggests that a further major sand movement took place during the period 5800–4200 cal BP, a period of widespread sand drift in NW Europe. The analyses of the sub-tidal deposits have also reinforced the current theory of machair evolution.
Low altitude sandy plains (machair) are a common feature of the Atlantic coasts of the Outer Hebrides. They formed as a result of shoreward movement of material consequent upon a rise in Holocene sea levels. A number of earlier, partially inconclusive, investigations into machair evolution proposed that fuller understanding could arise from an examination of inter-tidal organic deposits, in so far as these could provide a fossil proxy record of the processes involved in machair formation. Study of a series of inter-tidal peats sites located on a beach platform at Borve, island of Benbecula, provided both spatial and chronological evidence for sand movement as well as furnishing new data on vegetational and environmental history. The pollen diagrams show a flora in which Calluna vulgaris (heather) and Poaceae (grass) are frequent dominants, while such arbroeal taxa as Betula (birch) and Corylus avellana-type (cf. hazel) are notable. The existence of birch–hazel woodland for the period c. 8855–6190 BP might conceivably have had a retarding effect on sand movement. Later cycles of sand movement would not have met such obstruction with the consequence that sand mobility and machair plain evolution could have been faster. Sand arrival at the seaward site (Borve 3), is dated to c. 6735 BP and it continued until c. 6045 BP, after which it slowed before increasing again from around 5990 BP. This sand incursion produced a machair plain over the Borve sites as part of a continuous, but variously paced, marine and aeolian process. The presence of charcoal from c. 6860 BP, with a major increase in charcoal to pollen ratios by 6190 BP, may suggest that natural or intentional burning of the vegetation cover of the machair occurred in Mesolithic times; if the burning was anthropogenic in origin, then it pushes the possible involvement of humans in machair destabilisation to a time long before the previously proposed Neolithic period. A wet slack deposit, dated to 3400 ± 70 BP, indicates a time when sand movement overwhelmed the area around the landward site (Borve 1) and when the rate of sand movement was likely to have been impeded. The data from Borve suggest that evolution of machair landforms occurs at a slow, variable rate and that there is considerable long-term stability.
Sedimentary sequences in lower Strathspey provide a record of Late Pleistocene interglacial and glacial environments. After deposition of till and glacifiuvial sediments, probably in Oxygen Isotope Stage 6, a soil developed at Teindland and Redburn which contains downward translocated pollen. This indicates that the earliest vegetation was woodland with grassland openings, Pinus-Alnus at Teindland and Alnus-Corylus at Red Burn. Podzolisation of the soil ended with an influx of sands derived from erosion of the surrounding slopes, at Teindland perhaps a response to extensive burning during a grassland phase. The combined pollen and sedimentary evidence suggests events at the close of an interglacial. Luminescence dates of 79 ± 6 and 67 ± 5 ka for the sands over the soil suggest that the soil developed in Oxygen Isotope Stage 5e. Overlying the soil and sands at Teindland are glacigenic debris flows, perhaps reflecting glaciation during Oxygen Isotope Stage 4. Three, undated, younger till units, with interbedded gravels, also occur in the surrounding area and provide evidence of the complex glacial history of lower Strathspey since Oxygen Isotope Stage 5.
Interst in the Roman incursions into Scotland has a long history and, despite the numerous works that have appeared on the subject, there is still no diminution in the appearance of new writings. Of considerable interest is the recent appearance of a paper by Hanson and Breeze which undertakes a critique of existing studies of Roman Scotland and the nature of the data on which they depend, while also suggesting lines along which future enquiry might proceed. Several statements made by them are pertinent to the findings to be reported here. The first of these is that, ‘the relationship between the occupying Roman forces and the indigenous population is relatively poorly understood’. A second is that, ‘the pax Romana has frequently been cited as the occasion for changes in settlement patterns in north Britain’. The third, relating to the impact of the Roman arrival on agriculture and the environment, is that ‘…the pattern which is beginning to emerge suggests that the effect of the Roman army's presence was minimal’.
Deposits of windblown sand up to 4 m thick on the Torridon Sandstone massif of An Teallach are shown to be of predominantly niveo-aeolian origin, a form of sedimentation hitherto unrecognised in upland Britain. Sand grains weathered from bedrock and from exposed clasts on plateau areas are blown on to the winter snowpack on surrounding slopes. When the snow melts, the grains are lowered on to the underlying vegetation, which traps the sand and thus allows a stable deposit to accumulate. The deposits formed in this way are massive, poorly sorted and coarser than most aeolian deposits, comprising mainly medium sand (212–600μm) with a substantial proportion of coarse sand and even very small pebbles. The coarseness and poor sorting of the sands reflect the size of grains available for transportation, the strength of the wind, short transport distances and admixture of different grades of sand during deposition. Sand accumulation began in the Early Flandrian before c. 7900 BP, but was eventually much reduced by the establishment of vegetation cover over the plateau source area. Recent disruption of this vegetation cover triggered either by increased storminess or overgrazing resulted in extensive erosion of sand deposits on the plateau and their redeposition on surrounding slopes. Niveo-aeolian deposition continues on lee slopes at present, but is offset by erosion of unvegetated scarps at the margins of the deposits.
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