A boulder of millstone grit on Ilkley moor with a perfect circular hole probably formed by a large inclusion weathered out of the bedrock, West Yorkshire, England, United Kingdom, Europe

stone rock boulder geology millstone grit weathering erosion sedimentary ilkley ilkley moor yorkshire moor moorland triangle inclusion day outdoors landscape landscapes nature natural world physical geography surface processes rock formation rock formations eroded stones rocks boulders moors west yorkshire england great britain united kingdom europe photography color image travel destination horizontal