Here we reconstruct the last advance to maximum limits and retreat of the Irish Sea Glacier (ISG), the only land-terminating ice lobe of the western British Irish Ice Sheet. A series of reverse bedrock slopes rendered proglacial lakes endemic, forming time-transgressive moraine- and bedrock-dammed basins that evolved with ice marginal retreat. Combining, for the first time on glacial sediments, optically stimulated luminescence (OSL) bleaching profiles for cobbles with single grain and small aliquot OSL measurements on sands, has produced a coherent chronology from these heterogeneously bleached samples. This chronology constrains what is globally an early build-up of ice during late Marine Isotope Stage 3 and Greenland Stadial (GS) 5, with ice margins reaching south Lancashire by 30 ± 1.2 ka, followed by a 120-km advance at 28.3 ± 1.4 ka reaching its 26.5 ± 1.1 ka maximum extent during GS-3. Early retreat during GS-3 reflects piracy of ice sources shared with the Irish-Sea Ice Stream (ISIS), starving the ISG. With ISG retreat, an opportunistic readvance of Welsh ice during GS-2 rode over the ISG moraines occupying the space vacated, with ice margins oscillating within a substantial glacial over-deepening. Our geomorphological chronosequence shows a glacial system forced by climate but mediated by piracy of ice sources shared with the ISIS, changing flow regimes and fronting environments.

中文翻译：

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末次冰期期间终止于陆地的爱尔兰海冰川的演变

在这里，我们重建了爱尔兰海冰川 (ISG) 的最后一次前进到最大极限和后退，这是英国爱尔兰西部冰盖唯一的陆地终止冰瓣。一系列反向基岩斜坡使前冰湖成为地方性湖泊，形成时间越过的冰碛和基岩坝盆地，随着冰边缘退缩而演变。首次将冰川沉积物的光学受激发光 (OSL) 漂白曲线与沙子上的单粒和小等分 OSL 测量值相结合，从这些不均匀漂白的样品中产生了连贯的年表。这一年表限制了在海洋同位素第 3 阶段晚期和格陵兰体育场 (GS) 5 期间全球早期冰的形成，冰边缘到达兰开夏郡南部 30 ± 1.2 ka，随后在 28.3 ± 1 处前进 120 公里. 4 ka 在 GS-3 期间达到其 26.5 ± 1.1 ka 的最大范围。GS-3 期间的提前撤退反映了与爱尔兰海冰流 (ISIS) 共享的冰源的盗版行为，使 ISG 挨饿。随着 ISG 的撤退，GS-2 期间威尔士冰的机会主义重新出现在 ISG 冰碛上，占据了空出的空间，冰边缘在大量冰川过度加深内摆动。我们的地貌年代序列显示了一个由气候强迫但由与 ISIS 共享的冰源盗版、不断变化的流动状态和前沿环境介导的冰川系统。冰缘在大量冰川过度加深中摆动。我们的地貌年代序列显示了一个由气候强迫但由与 ISIS 共享的冰源盗版、不断变化的流动状态和前沿环境介导的冰川系统。冰缘在大量冰川过度加深中摆动。我们的地貌年代序列显示了一个由气候强迫但由与 ISIS 共享的冰源盗版、不断变化的流动状态和前沿环境介导的冰川系统。