High Force is a well known waterfall in North East England which has been attracting visitors since the c18th including the painter J. M. Turner and the novelist Sir Walter Scott. You’ll find it in all its majesty on the River Tees within the Moor House – Upper Teesdale National Nature Reserve, itself within the North Pennines AONB (and European Geopark), in Upper Teesdale, County Durham (UK). It can be viewed extensively from the Teesdale Way which passes nearby, or there is a private footpath on the other side of the river from the High Force Hotel for which a modest toll is charged by the Raby Estate.
Location NY 880283
By no means the longest waterfall in England (that honour goes to Cautley Spout in Cumbria’s Howgill fells), when in full spate High Force delivers a greater volume of water than any other waterfall in England. With a continuous roar, the river drops vertically into a pool 21 m (70 ft) below, past two very distinctive bands of rock, the first of which is the lower part of the Whin Sill igneous intrusion or, more accurately, the Great Whin Sill and the darker Tyne Bottom Limestone, with a thinner, intervening layer of metamorphosed sandstone (baked by the intense heat of the sill when it was intruded ~300 million years ago).
At High Force the river runs in two distinct channels: the main one is the left-hand channel (looking upstream) but after extended periods of heavy rain – like Storm Ciara in 2020 – the water spills over into the right-hand channel at which point the falls are in full spate. Over time, the turbulence at the bottom of the falls erodes the softer Carboniferous limestone, undermining the igneous rock of the Whin Sill, eventually causing it to collapse, and so the face of the falls moves upriver.
Before Cow Green Reservoir was constructed c1970 the river was fed by a natural lake where the reservoir is now, known as The Weel. When the water level rose it would spill over the Whin Sill at Cauldron Snout sending devastating volumes of water over High Force in a torrent that gained a grim reputation as the ‘Tees Roll’ and was responsible for much damage and death down the dale.
British Geological Survey (BGS). “Geology & Landscape of Upper Teesdale – an Excursion.” Earthwise (British Geological Survey), http://earthwise.bgs.ac.uk/index.php/Geology_and_landscape_of_Upper_Teesdale_-_an_excursion. Accessed 06 10 2020.
Geology North. The Whin Sill. Geology North. https://www.geologynorth.uk/the-whin-sill/. Accessed 05 10 2020.
Sopwith, Thomas. An Account of the Mining Districts of Alston Moor, Teesdale and Weardale. W. Davison, 1833. Google Books. Accessed 06 10 2020.
Teesdale Mercury. “Storm Force: Dale battered by flooding as roads close.” Teesdale Mercury, 18 02 2020, https://www.teesdalemercury.co.uk/news/storm-force-dale-battered-by-flooding-as-roads-close. Accessed 06 10 2020.