ABSTRACT Medial moraines deposited by former glaciers and ice sheets are rare in Scotland. The most prominent example is the Sgriob na Caillich moraine, which consists of two to four parallel belts of angular quartzite boulders that extend northwestwards for over 3.5 km from the SW flank of Beinn an Oir on the Isle of Jura. The boulder belts extend to within 300 m of the present coastline, where they are truncated by a low bluff and raised marine terrace. The source of the moraine coincides with bedrock gullies and cliffs that represent the scars of former rock-slope failure(s), indicating that the moraine debris was sourced by one or more rockfalls or rockslides onto the ice surface after Beinn an Oir had emerged from the thinning ice cover as a nunatak. Exposure dating of boulders on the moraine indicate that it formed at 16.6 ± 0.8 ka, consistent with the timing of ice-sheet retreat in this sector. The alignment of the moraine indicates ice-margin retreat to the SE; as regional ice-sheet retreat across the adjacent offshore shelf was to the NE, this anomaly implies that a residual icefield became stranded on Jura during ice-sheet retreat.

中文翻译：

---

苏格兰地貌示例 45：Sgriob na Caillich：侏罗岛上的山体滑坡内侧碛

摘要 由前冰川和冰盖沉积的内侧冰碛在苏格兰很少见。最突出的例子是 Sgriob na Caillich 冰碛，它由 2 到 4 条平行的角状石英岩巨石带组成，从侏罗岛上的拜恩奥厄尔西南侧向西北延伸超过 3.5 公里。巨石带延伸到目前海岸线的 300 m 以内，在那里被低矮的悬崖和凸起的海洋阶地截断。冰碛的来源与基岩沟壑和悬崖重合，这些沟壑和悬崖代表了以前岩石斜坡破坏的疤痕，表明冰碛碎片是由一个或多个落石或岩石滑坡产生的变薄的冰盖就像一个 nunatak。冰碛上巨石的曝光年代表明它形成于 16.6 ± 0.8 ka，与该部门冰盖退缩的时间一致。冰碛的排列表明冰缘向东南退缩；由于区域性冰盖越过相邻的近海陆架后退到东北部，这种异常意味着在冰盖后退期间残留的冰原搁浅在侏罗山上。