Geology
There are three distinct geological areas in Upper and Mid Swaledale. the upper reaches of the river flow over Carboniferous, Permian and Triassic rock, all of which are atop a layer of Lower Paleozoic beds. These rocks are rich in minerals and metalliferous sulfide ores such as Galena, Sphalerite, Chalcopyrite and Bravoite. There are also deposits of Fluorite, Barite, Witherite, Calcite, Dolomite and Barytocalcite.
Along the valley sides can be seen the typical Dales geology of Yoredale beds, alternating strata of Limestone and Gritstone. Small seams of coal, particularly around Tan Hill, have been found and worked. During the last Ice Age, the glacier that dominated the valley was responsible for broadening it and altering the course of the river around Keld and Round Howe. It was also responsible for cutting the Kisden Gorge. Retreat moraines lower in the river valley can be seen around Gunnerside and Grinton Bridge.
Read more about this topic: River Swale