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

marked by hummocky moraine/kame and kettle topography around Pyle, Margam (Margam- Pyle Moraine)
and Llanilid (Bowen, 1970). A large area of kame and kettle topography located between Pencoed and
Newport marks the ice sheet margin fed by glaciers from the South Wales Coalfield dValleysT ice
(Charlesworth’s, 1929 “Glamorgan Piedmont Glacier”). This feature was later confirmed by Bowen (1970)
as the ice sheet margin between Pencoed and Cardiff, but regarded by him as a recessional position between
Cardiff and Newport based upon reconstructions of an ice lobe flowing offshore in that area, fed by the
coalesced dValleyT and eastern coalfield glaciers (Welch and Trotter, 1961).
In Pembrokeshire Charlesworth’s SWEM limit was drawn along the north Pembroke coast, based upon
the Gwaun–Jordanston marginal meltwater and glacial lake overflow channels and the
glacifluvial/glacilacustrine sediment bodies at Banc-y-Warren and Tregaron. The Gwaun–Jordanston
channels were later re-interpreted as subglacial in origin by Bowen and Gregory (1965) and Bowen (1967),
thereby suggesting an ice limit further to the south and questioning the existence of lakes in the area.
However, the sediments and landforms at Banc-y-Warren and Tregaron, together with evidence of former
lacustrine environments at other sites, provide clear documentation of glacifluvial and glacilacustrine
environments during glacier recession, as would be expected if glacier ice uncovered such a large system of
deep subglacial channels. Watson (1970) used pingo distribution to demarcate the margins of the last ice
sheet in southwest Wales but this has been questioned via various alternative interpretations (e.g. Handa and
Moore, 1976; Bowen, 1973a,b, 1974). A long history of study of the Banc-y-Warren succession has resulted
in a thorough documentation of the internal structures and sedimentology. Helm and Roberts (1975)
suggested a deltaic origin, explaining the large scale faulting in the sequence as a result of subaqueous mass
failure. This supported the contention of Jones (1965) that the lower Teifi Valley had hosted a lake during
Late Devensian glaciation. Whilst accepting that some sediments at Banc-y-Warren were deltaic, Allen
(1982), and later Worsley (1984), suggested that the majority of the material was glacifluvial outwash and
that a small supraglacial lake was formed at the same location some time during deglaciation. Although
Banc-y-Warren has been cited as a possible Gilbert-type raised marine delta by Eyles and McCabe (1989), its
location on an interfluve high above the Teifi Valley mouth clearly requires Irish Sea glacier ice impinging
on the coast. Moreover, the 140 m altitude of the feature is far in excess of predicted marine limit altitudes for
the Irish Sea basin (McCarroll, 2001). Another glacifluvial feature to the south of Banc-y-Warren at Trefigin
was one of a number of features regarded as eskers by Bowen (1982a,b; Monington esker) but which has
recently been interpreted as an erosional remnant of a former outwash plain or kame terrace associated with
the Irish Sea glacier by Owen (1997). Crimes et al. (1994) mapped a series of kame terraces, eskers, kames,
meltwater channels and ice-contact proglacial outwash (including the Monington Esker), that in some places
grade into features and sediments associated with a deglacial Lake Teifi such as fan deltas and lake sediments.
A linear suite of these depositional features is used by Crimes et al. (1994) to reconstruct the Irish Sea ice
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