Editing High Force (section)

==Geology==
[[File:High Force from the Pennine Way - geograph.org.uk - 1726862.jpg|thumb|upright=1.4|A view including the now rarely seen second fall on the right]]
[[File:High Force after a storm - geograph.org.uk - 111699.jpg|thumb|upright=1.4|Storm conditions in 1968]]
High Force was formed where the River Tees crosses the [[Whin Sill]] – a hard layer of [[igneous rock]] (also seen at [[Hadrian's Wall]] and other locations). The [[waterfall]] itself consists of three different types of rock. The upper band is made up of [[whinstone]], or [[dolerite]], a hard igneous rock which the waterfall takes a lot of time to erode. The lower section is made up of [[Carboniferous Limestone]], a softer rock which is more easily worn away by the waterfall. Between these two layers is a thinner layer of Carboniferous sandstone, which was baked hard when the Whin Sill was molten 295 million years ago. The wearing away of rock means that the waterfall is slowly moving upstream, leaving a narrow, deep [[Canyon|gorge]] in front of it. The length of the gorge is currently about {{convert|700|m}}. The [[bed load]] (rocks that the river is carrying) is mainly composed of large boulders, which are rolled along the river bed. Upstream of the waterfall, the river is narrow; downstream, it widens and meanders.