Definition: rock hills shaped by the passage of ice to give a smooth up-ice side and a rough, plucked and cliffed surface on the down-ice side. The upstream surface is often marked with striations.

A small roche moutonnée north of Brinkies Brae developed in jointed basement rocks. Ice movement L-R.

Ice-moulded bedforms like roches moutonnées are best developed in strong, jointed rocks. It is no surprise therefore that these features appear to be rare on the Devonian sandstone terrains that dominate Orkney. A few examples do occur on the basement rocks around Stromness and Yesnaby and here the whaleback forms are partly inherited from the sub-Devonian surface. Other roches moutonnées may lie concealed beneath drapes of till, especially on East Mainland.

  • During the periods of maximum cold in the Quaternary, major ice sheets covered Scotland. An ice stream hundreds of metres thick curved out from the Moray Firth to cross the plain of Caithness and flow over Orkney towards ice limits close to the edge of continental shelf.

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  • In the gently-dipping sandstone terrain of Orkney, it is often difficult to pick out classic landforms of glacial erosion. Low-lying areas often show a pronounced SW-NE grain to the topography, parallel to the main direction of ice sheet flow. ...

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  • Glacial deposition is largely confined to low-lying areas on Orkney, where thicknesses of till may exceed 10 m. The glacial deposits drape the landscape, smoothing its outlines. Ice-marginal features are largely unrecognised outside Hoy ...

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  • Westray is the furthest northwest of the Orkney islands. The total area is 47 square kilometres, not huge but the irregular shape gives it a long coastline of almost 80 kilometres, a good place to look for glacial striations. The bedrock of the whole of the island is made up of the cyclical Rousay Flagstone Formation. ...

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