Читать книгу Walking in the Yorkshire Dales: North and East. Howgills, Mallerstang, Swaledale, Wensleydale, Coverdale and Nidderdale онлайн

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The lines of fracture are dramatically evident in the three main Craven Faults, which cut across the southern part of the national park. Giggleswick Scar – the line of towering cliffs overlooking the B6480 west of Settle – is part of the South Craven Fault, which continues its line southeast towards Skipton. The Mid-Craven Fault is marked by a long line of cliffs of which Malham Cove and Gordale Scar are a part, while the North Craven Fault runs parallel to it at the southern lip of Malham Tarn.

In a few places, the limestone of the block has been worn away to expose rocks from an even earlier era, the Ordovician, which, unlike the even Carboniferous formations, are extravagantly crumpled, and consist of slates, grits and mudstones. These can be seen in the quarries of Ribblesdale and around Ingleton, and are also exposed as an impervious basement layer in the southern valleys, perhaps most vividly in Thornton Force and along the Ingleton Falls.

The character of the Howgills clearly sets them apart from the rest of the Dales, and with the Middleton Fells, they are separated from the Askrigg Block by another fracture line – the Dent Fault. This runs in a rough north–south line east of Sedbergh, but here the displacement has been in the opposite direction, elevating the older rocks that lie to the west. Geologically these hills are part of the Lake District, and are composed of much-folded metamorphosed slates and grits from the Silurian period, about 100 million years older than the Carboniferous rocks making up the Askrigg Block. Their grassy flanks sweep steeply upwards from deep ravines to broad, rounded tops, whose long interconnecting ridges, once attained, offer immensely satisfying walking.