Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Abstract Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Clark, J. Articles by Xu, S. Search for Related Content GeoRef GeoRef Citation

Cosmogenic ¹⁰Be chronology of the last deglaciation of western Ireland, and implications for sensitivity of the Irish Ice Sheet to climate change

¹ School of Environmental Science, University of Ulster, Coleraine, County Londonderry BT52 1SA, UK
² Natural Environment Research Council Cosmogenic Isotope Analysis Facility, Scottish Enterprise Technology Park, East Kilbride G75 0QF, UK
³ Department of Geosciences, Oregon State University, Corvallis, Oregon 97331, USA
⁴ Department of Geography, National University of Ireland, Maynooth, County Kildare, Ireland
⁵ Scottish Universities Environmental Research Centre, Scottish Enterprise Technology Park, East Kilbride G75 0QF, UK

View larger version (32K): [in this window] [in a new window]   Figure 1. Map of Ireland showing general ic-flow patterns and ice limits associated with the Killard Point Stadial (lines with single hachures) and earlier events (from McCabe et al., 1998). Areas of this study in western Ireland are outlined, corresponding to areas shown in Figures 2 and 6. CB—Clew Bay; KB—Killala Bay; DB—Donegal Bay.

View larger version (54K): [in this window] [in a new window]   Figure 2. Glacial landforms in western Ireland between Clew Bay and Killala Bay associated with most recent ice limit shown by heavy dashed line corresponding to the Tawnywaddyduff moraine. See Figure 1 for location of area.

View larger version (111K): [in this window] [in a new window]   Figure 3. Photographs illustrating field relations of moraines and samples for cosmogenic dating. (A) Hummocky, bouldery moraine in the Furnace Lough area. (B) Hummocky moraine near Beltra Lough. (C) Internal sedimentary architecture of hummocks near Beltra Lough. Field notebook for scale (10 cm long). (D) Proximal slope of Tawnywaddyduff moraine in its type area. (E) Coarse, poorly sorted gravels comprising Tawnywaddyduff moraine where it abuts the eastern slopes of the Nephin Beg Range. (F) Well-defined lateral moraine crossing the western slopes of Nephin. (G) Right-lateral moraine descending slope from right to left, immediately to the east of Easky Lough. (H) Well-defined moraines backfilling valley between Benbulbin and Truskmore, south of Donegal Bay (see Fig. 6).

View larger version (153K): [in this window] [in a new window]   Figure 4. Location of samples for cosmogenic dating in the Furnace Lough area (see Table 1 for geographic coordinates).

View larger version (116K): [in this window] [in a new window]   Figure 5. Digital elevation model of topography in western Ireland and bathymetry on the floor of Donegal Bay. Multibeam bathymetry data were acquired in 2002 onboard the R/V Celtic Voyager under the Irish National Seabed Survey (data collected in 2002 by Geological Survey of Ireland). The Tawnywaddyduff moraine is shown by line with single hachures.

View larger version (34K): [in this window] [in a new window]   Figure 6. Glacial landforms in western Ireland between the Ox Mountains and Lough Melvin. Prominent lateral moraines marking upper limit of last ice advance occur in valley between Benbulbin and Truskmore (see Fig. 3H) and on western slope of Cornwal South. See Figure 1 for location of area.

View larger version (71K): [in this window] [in a new window]   Figure 7. Location of samples for cosmogenic dating from the Ox Mountains. Perspective is oblique view looking south from Donegal Bay.

View larger version (17K): [in this window] [in a new window]   Figure 8. 10Be exposure ages from Furnace Lough. Error bars correspond to 1 analytical uncertainty only. The black horizontal line identifies the mean age of the data set. Shaded gray band corresponds to 1 uncertainty (the standard error of the full data set). Inset graph shows the probability curves for the individual exposure ages (light-gray curves). Probability values are normalized so that each probability distribution is equal to 1. The sum of the probabilities is shown as the thick black curve.

View larger version (18K): [in this window] [in a new window]   Figure 9. 10Be exposure ages from the Ox Mountains. Error bars correspond to 1 analytical uncertainty only. The black horizontal line identifies the mean age of the data set. Shaded gray band corresponds to 1 uncertainty (the standard error of the full data set). Inset graph shows the probability curves for the individual exposure ages (light-gray curves). Probability values are normalized so that each probability distribution is equal to 1. The sum of the probabilities is shown as the thick black curve.

View larger version (30K): [in this window] [in a new window]   Figure 10. (A) Record of ice-rafted debris from marine core DAPC2 from the northeast Atlantic, ~200 km west of northwest Scotland (Knutz et al., 2007). (B) Our mean 10Be age from combined Furnace Lough and Ox Mountain data set (black solid dot; 1 internal error shown by black line; 1 error, including production-rate error, shown by gray line) and calibrated radiocarbon dates (Stuiver et al., 2005) that constrain ages of the Killard Point (K.P.) and Clogher Head (C.H.) stadials during last deglaciation (duration indicated by gray boxes) (Lowe et al., 2004; McCabe and Clark, 1998, 2003; McCabe et al., 2005, 2007). Specifically, these ages identify interstadials represented by raised marine deposits that underlie and overlie glacial sediments associated with the two stadials. (C) Percent Neoglobquadrina pachyderma from marine core DAPC2. (D) The 18O record from the Greenland Ice Sheet Project 2 (GISP2) ice core (Grootes et al., 1993; Stuiver and Grootes, 2000). N. pachy—Neoglobquadrina pachyderma.

View larger version (40K): [in this window] [in a new window]   Figure 11. Ice-surface reconstruction for a portion of the southwestern sector of the Irish Ice Sheet during the Killard Point Stadial. Dark-gray areas labeled Ox Mountains and Benbulbin remained above the ice surface as nunataks. The light-gray area is distribution of Rogen moraine (McCabe et al., 1998).