Knowledge of the glacial chronologies for the Last Glacial Maximum (LGM) helps in understanding the interactions between climate, topography and glacier development. In this sense, the investigation of the Lake Orta moraine amphitheatre (Alpine foreland, northern Italy) allowed spatial and temporal reconstruction of the Orta Glacier. The end‐moraine system was investigated by means of geomorphological field surveys, analysis of 13 rock samples for cosmogenic ¹⁰Be and ³⁶Cl concentrations, and remote sensing analysis. The dating results indicate that the age of the outer moraine belt is concordant with the LGM culmination at 26.5–23 ka, as found in other amphitheatres in the Alps. This new age estimate of the outermost moraines shows that the maximum extent of the Orta Glacier during the LGM was significantly bigger than recently suggested. A younger stabilization phase of the glacier front at about 19 ka indicates that the onset of the withdrawal of glaciers from the lower Alpine valleys started later. Provenance analysis of the boulders shows that the greatest contribution of ice to the Orta Glacier came from the Anzasca Valley rather than the major Ossola Valley. This reflects the closeness (about 45 km) to the foreland of the high‐elevated accumulation area of the Monte Rosa massif (4634 m a.s.l.), whose eastern glacier seems to have reached the lower valley faster than the trunk Toce Glacier. This fact underlines the key role played by high‐elevation accumulation areas that are located close to the foreland in controlling the path and geometry of major glaciers in the Alps.

中文翻译：

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最后一次冰川最大时期奥尔塔冰川（欧洲阿尔卑斯山）的时间和流型

末次冰川最大值（LGM）的冰川年代学知识有助于理解气候，地形和冰川发展之间的相互作用。从这个意义上讲，对奥尔塔冰m湖露天剧场（意大利北部的阿尔卑斯山前陆地区）的调查允许对奥尔塔冰川进行时空重建。通过地貌学实地调查研究了冰mor末系统，分析了宇宙成因的¹⁰ Be和³⁶的13个岩石样品Cl浓度，以及遥感分析。测年的结果表明，冰outer外带的年龄与在26.5-23 ka的LGM高潮相吻合，正如在阿尔卑斯山的其他圆形剧场中所发现的那样。对最外层冰rain的这一新的年龄估计表明，在LGM期间Orta冰川的最大范围明显大于最近的建议。大约19 ka的冰川锋线处于较年轻的稳定期，表明从较低的高山山谷撤出冰川的开始较晚。对巨石的出处分析表明，冰对Orta冰川的最大贡献来自安萨斯卡河谷，而不是主要的奥索拉河谷。这反映了蒙特罗莎地块（4634 m asl）到高海拔堆积区前陆的距离（约45 km），其东部冰川到达谷底的速度似乎比树干托斯冰川快。这一事实突显了靠近前陆的高海拔堆积区在控制阿尔卑斯山主要冰川的路径和几何形状方面所起的关键作用。