Esker formation and the nature of deglaciation: the Ballymahon esker, Central Ireland

Delaney, Catherine (2001) Esker formation and the nature of deglaciation: the Ballymahon esker, Central Ireland. North West geography, 1 (2). pp. 23-33. ISSN 1476-1580

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Abstract

The Ballymahon esker, central Ireland, is one of a series of eskers formed shortly after a drumlinising event towards the end of the last glaciation. It lies within a belt composed of segments, each of which comprises a narrow, sharp-crested ridge composed of short-grained sediments leading down-ice to a flat-topped terminus. The segments are interpreted as subglacial tunnel/channel to ice-marginal 'beads', deposited sequentially as the ice margin retreated. Tunnel/channel deposits underlie esker remnants, indicating that short-lived drainage routeways existed to either wide of the main routeway during ice margin retreat. The evidence indicates that deglaciation in this area was characterised by stagnation-zone retreat, rather than mass in situ downwasting of the ice.