SH6760 : A glacier passed this way A glacier, or weathering and scour from other sources of displacement energy, or residual systems in the rock formation, or a slide scratch from solifluction and boulder, rock wedge slide damage to surface, or looking at Tryfan and the streams I wonder how much of this is mining, quarry damage from rocks slid down the slope by the excavators, leaving a trail of disturbance. It seems the stream may have been diverted by cut rock sections by the Ogwen Nant Ffrancon miners and slate quarry, the marsh has been reduced for grazing ? but water diverted away from Llugwy east to the west. The whole area has been subject to devastation as North Wales is really just a mining wreck, Mid Wales has a lot of mines but some of the land is still grazing and ex arable as well as new forest, which also has obscured the original rocks and cuttings, Scotland is the same in many regions, now trees obscure once clear tourism views. The coast sediments marsh are really products of industrial exploitation. So maybe ice, maybe boulder slide natural or industrial. How do we know, we may never know these days which is why I concentrated on Hydrology on present day soils and rock weathered, at least we can measure and observe that feature. Mike