Mike J Smith Paul Dunlopf and Chris D Clark

*School of Earth Sciences and Geography, Kingston University, Penrhyn Road, Kingston-upon-Thames, Surrey KT1 2EE, UK fSchool of Environmental Sciences, University of Ulster, Coleraine, BT52 ISA, Northern Ireland, UK $Department of Geography, University of Sheffield, Winter Street, Sheffield S10 2TN, UK

Figure 75.1 Summary map of glacial bedforms for Ireland, incorporating drumlins and ribbed (rogen) moraine including extensive ribbed moraine fields reported by Clark & Meehan (2001). Note the areas of cross-cutting ribbed moraine in north central Ireland indicating shifts in the ice divide.

Drumlin Belt Ireland

Figure 75.1 Summary map of glacial bedforms for Ireland, incorporating drumlins and ribbed (rogen) moraine including extensive ribbed moraine fields reported by Clark & Meehan (2001). Note the areas of cross-cutting ribbed moraine in north central Ireland indicating shifts in the ice divide.

their distribution over Ireland indicates that a major ice divide must have existed over the northwest Irish Coast with ice extending westwards onto the continental shelf.

Glacial lineaments (drumlins and larger streamlined forms) visible on the DEM conform to many published accounts indicating flow convergence into many of the bays and inlets of Ireland. In addition we have identified strong patterns of streamlining in Tipperary and Galway, far to the south of the main drumlin belt. In Clew Bay (half way up the west coast) a series of wave-like and irregular ridges are apparent (Fig. 75.3) that we interpret as ribbed moraine, possibly forming the western end of the main ribbed moraine belt, created beneath ice flowing towards the north-northwest. Our explanation deviates from the usual interpretation of these landforms as drumlins recording ice flow westwards into the bay (Warren, 1992). Jordan (1997) used satellite imagery to map these landforms, recording them as drumlins formed by ice flowing eastwards onshore. Figure 75.4 depicts some classic drumlins and streamlining south of Galway Bay. Surprisingly, the well known drumlins around Strangford Lough appear very poorly expressed on the DEM. We have mostly

Figure 75.2 Oblique view of the megascale ribbed moraine landscape (after Clark & Meehan, 2001). Note the arcuate planform shape and regularly spaced, anastamosing, ridges. Diagnostic features include consistent size (in relation to neighbours), downstream pointing horns and undulating ridge crests. Image is approximately 30 km across in the foreground and is looking northwards across Co. Monaghan. (Original data used to produce visualization, copyright University of Manchester/University College London, 2001.)

Figure 75.2 Oblique view of the megascale ribbed moraine landscape (after Clark & Meehan, 2001). Note the arcuate planform shape and regularly spaced, anastamosing, ridges. Diagnostic features include consistent size (in relation to neighbours), downstream pointing horns and undulating ridge crests. Image is approximately 30 km across in the foreground and is looking northwards across Co. Monaghan. (Original data used to produce visualization, copyright University of Manchester/University College London, 2001.)

Figure 75.4 Oblique view of classic drumlins and larger scale streamlining just southeast of Galway Bay. Image is approximately 20 km across in the foreground and is looking northwards across Co. Clare. (Original data used to produce visualization, copyright University of Manchester/University College London, 2001.) (See www.blackwellpublishing.com/ knight for colour version.)

Figure 75.4 Oblique view of classic drumlins and larger scale streamlining just southeast of Galway Bay. Image is approximately 20 km across in the foreground and is looking northwards across Co. Clare. (Original data used to produce visualization, copyright University of Manchester/University College London, 2001.) (See www.blackwellpublishing.com/ knight for colour version.)

Figure 75.3 Vertical view of bedforms around Clew Bay, Co. Mayo. The DEM data clearly demonstrate that these are not drumlins but are a series of WSW-ENE trending ridges with some sinuosity, which we interpret as ribbed moraine. These exhibit preferential planform concavity towards the north-northwest (usually taken to indicate flow towards this direction). Note the superimposition of drumlins on top of the ribbed moraine on the eastern side of the image. (Original data used to produce visualization, copyright University of Manchester/University College London, 2001.) (See www. blackwellpublishing.com/knight for colour version.)

Figure 75.3 Vertical view of bedforms around Clew Bay, Co. Mayo. The DEM data clearly demonstrate that these are not drumlins but are a series of WSW-ENE trending ridges with some sinuosity, which we interpret as ribbed moraine. These exhibit preferential planform concavity towards the north-northwest (usually taken to indicate flow towards this direction). Note the superimposition of drumlins on top of the ribbed moraine on the eastern side of the image. (Original data used to produce visualization, copyright University of Manchester/University College London, 2001.) (See www. blackwellpublishing.com/knight for colour version.)

Ribbed Moraines

Figure 75.5 Vertical view of rounded hummocks just south of Lough Neagh, Co. Armagh. Note the ovoid nature of the landforms with no preferred orientation. Image is approximately 20km across. (Original data used to produce visualization, copyright University of Manchester/University College London, 2001.)

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Figure 75.5 Vertical view of rounded hummocks just south of Lough Neagh, Co. Armagh. Note the ovoid nature of the landforms with no preferred orientation. Image is approximately 20km across. (Original data used to produce visualization, copyright University of Manchester/University College London, 2001.)

interpreted this area as ribbed moraine. It might be that the field-mapped drumlins are below the resolution of the DEM or that they have been confused with ribbed moraine. In many places subglacial bedforms take the form of rounded hummocks with isolated summits (Fig. 75.5). It remains to be ascertained what these are: a new type of bedform or degraded versions of drum-lins or ribbed moraine.

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