TY - JOUR
T1 - Identification and significance of ice-flow-transverse subglacial ridges (Rogen moraines) in northern central Ireland
AU - Knight, J
AU - McCabe, AM
PY - 1997/11
Y1 - 1997/11
N2 - In the Omagh Basin, north central Ireland, subglacial diamict ridges lie transverse to southwestward Late Devensian (ca. 23-13 ka) ice flow. These ridges (0.5-2.5 km long, 100-450 m wide, 15-35 m high), are similar morphologically to Rogen moraines, which have not been described previously from the British Isles. The crests of some transverse ridges are streamlined, cross-cut or overprinted by drumlins, whereas other ridges are unmodified and were not affected by later drumlinisation. At Kilskeery, west-east trending eskers overlying unmodified transverse ridges post-date drumlinisation (17-14 C-14 ka). Esker formation shows that the subglacial thermal regime changed from cold-based, favouring bedform preservation, to warm-based with meltwater flowing through enclosed subglacial channels. Patterns of flow-transverse-ridges and spatial variations in the degree of bedform modification record dynamic changes in regional subglacial environments during the last deglacial cycle. This ice-mass variability cannot be reconciled with current Irish glacial models, which are based on immobile ice centres and ordered stages of ice retreat. In a wider context, these changes in bedform patterns and basal ice regimes have a similar signature to millennial-scale ice-mass oscillations recorded by dated proxy evidence elsewhere in the amphi-North Atlantic.
AB - In the Omagh Basin, north central Ireland, subglacial diamict ridges lie transverse to southwestward Late Devensian (ca. 23-13 ka) ice flow. These ridges (0.5-2.5 km long, 100-450 m wide, 15-35 m high), are similar morphologically to Rogen moraines, which have not been described previously from the British Isles. The crests of some transverse ridges are streamlined, cross-cut or overprinted by drumlins, whereas other ridges are unmodified and were not affected by later drumlinisation. At Kilskeery, west-east trending eskers overlying unmodified transverse ridges post-date drumlinisation (17-14 C-14 ka). Esker formation shows that the subglacial thermal regime changed from cold-based, favouring bedform preservation, to warm-based with meltwater flowing through enclosed subglacial channels. Patterns of flow-transverse-ridges and spatial variations in the degree of bedform modification record dynamic changes in regional subglacial environments during the last deglacial cycle. This ice-mass variability cannot be reconciled with current Irish glacial models, which are based on immobile ice centres and ordered stages of ice retreat. In a wider context, these changes in bedform patterns and basal ice regimes have a similar signature to millennial-scale ice-mass oscillations recorded by dated proxy evidence elsewhere in the amphi-North Atlantic.
U2 - 10.1002/(SICI)1099-1417(199711/12)12:6<519::AID-JQS313>3.0.CO;2-Q
DO - 10.1002/(SICI)1099-1417(199711/12)12:6<519::AID-JQS313>3.0.CO;2-Q
M3 - Article
VL - 12
SP - 519
EP - 524
JO - Journal of Quaternary Science
JF - Journal of Quaternary Science
SN - 0267-8179
IS - 6
ER -