The last British Ice Sheet: A review of the evidence utilised in the ...

moraine deposited by the Devensian ice sheet occurs on Jura where it documents former northwesterly ice
flow over the island (Dawson, 1979). Evidence of moraines and a possible minor readvance by Devensian ice
on Islay occurs at Loch Indaal (Synge and Stephens, 1966; Peacock and Merritt, 1997). Areas of hummocky
moraine have been mapped on Islay and Jura by McCann (1964), Dawson (1982) and Peacock (1984) and
related to ice sheet recession from the islands. The innermost of these moraines is composed of ice-contact
deltaic foresets that have been glacitectonized and overprinted by till.
Moraines deposited during ice sheet recession occur in other parts of northern Scotland where their
implications for glacier dynamics and age remain to be fully elucidated. Numerous transverse moraine ridges
document recession of glacier ice on Harris and are interpreted by Peacock (1984, 1991) as the products of
active glacier margins. Mykura and Phemister (1976) report a moraine belt on Papa Stour, Shetland Islands
that may represent ice marginal stabilization after recession from the continental shelf. Moraines are rare in
nearby Caithness and comprise ridges and mounds of gravel lying on both the local and shelly tills (Peach
and Horne, 1881b; Crampton and Carruthers, 1914). They are thought to relate to local ice that became
dominant after the recession of the northerly flowing Moray Firth ice.
It is evident from a number of studies reviewed above that meltwater channels are ubiquitous features in
the glacial landform legacy of Scotland. Many areas of meltwater channels were mapped in the 1960s and
1970s following the impact of the seminal work of the Scandinavian geomorphologists on glacial drainage
networks (e.g. Mannerfelt, 1945, 1949). Particularly significant was a paper by Sissons (1958a) in which the
influential ideas of Kendall (1902) on overspill channels were finally overthrown (see Ballantyne and Gray,
1984 and Evans, in press for review). There followed a large number of papers on the distribution and
interpretation of glacial meltwater channels in Scotland (e.g. Sissons, 1958a,b,c, 1960, 1961a,b, 1963b; Price,
1960, 1963, 1983; Derbyshire, 1961), demonstrating that glacial meltwater drained subglacially, marginally
and proglacially and that lake overspill channels were likely to occur only where other unequivocal evidence
for ice-dammed lakes existed (e.g. Russell, 1995).
2.2.2. Southern Scotland and Northumberland
Considerable accumulations of glacifluvial sediment have been often used as evidence for readvances by the
receding Highland and Southern Upland ice masses. Two eminent researchers of Scottish glacial
geomorphology, J.K. Charlesworth and J.B. Sissons were responsible for championing major regional
readvances, including the Lammermuir–Stranraer, Aberdeen–Lammermuir and Perth Readvances (detailed
briefly above). The Lammermuir–Stranraer Readvance of Charlesworth (1926a,b) and Sissons (1961c),
although later rejected by Sissons (1974a,b, 1976b), was based upon the occurrence of a prominent belt of
glacifluvial landforms in the Stranraer/ Galloway coast area and in central Scotland, specifically
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