Genesis of late pleistocene cross‐valley moraine ridges, South—Central Ulster, Northern Ireland

• Published in: Earth Surface Processes and Landforms
• Main Author: Dardis, George F.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1985
• Subjects: Cross Valley; Moraine Ridge; Ice Sheet
• Online Access: http://dx.doi.org/10.1002/esp.3290100507; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fesp.3290100507; https://onlinelibrary.wiley.com/doi/pdf/10.1002/esp.3290100507

Abstract Four genetic varieties of ice‐marginal cross‐valley moraine ridge have been identified in south‐central Ulster, Northern Ireland. Type I ridges are flat topped, composed of stratified, water‐lain sediments and formed by coalescence of a series of supraaquatic deltas. Type II ridges are sharp crested, composed of stratified, water‐lain sediments and formed by coalescence of a series of subaquatic deltas. Type III ridges show mixed morphological and sedimentological characteristics of type I and II ridges. Type IV ridges are sharp crested or hummocky, composed of poorly‐sorted and poorly‐stratified water‐lain sediments and formed by coalescence of a series of subaquatic sediment gravity flow cones. Field evidence indicates that cross‐valley moraine ridges in south‐central Ulster were deposited in proglacial lacustrine environments. Ridge type depended principally on (1) the nature of the proglacial bedrock slope; (2) the manner in which meltwater entered the proglacial zone; and (3) ice‐sheet behaviour during deglaciation, particularly within the ice‐sheet terminus zone.