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The River Ure at Slapestone Wath (Walk 28)

Named the Yoredale Series, because of its appearance in the valley of the River Ure – Wensleydale – this banded rock forms the basis of the northern portion of the national park, and extends further south as higher peaks and ridges. The upper levels of the layering culminate in a hard, impervious sandstone known as millstone grit, reflecting one of its uses, and the remnants of this form the southern hill tops and the high ground of the northern fells.

Although originally laid down in neat, horizontal bands, these rocks were subsequently folded by a massive earth movement that created the Pennines. Fractures separated the section underlying the Yorkshire Dales, known as the Askrigg Block, from the rest of the mountain chain, and it was pushed up from the south and the west, putting the Carboniferous strata of the block far above the younger rocks that lie to the south. The block tilts gently backwards, and whereas weathering has exposed the older limestones in the southwest of the area, the more recent Yoredale rocks remain on top to the northeast.