After the opening of the North Atlantic, more Earth movements affected northern England. Periods of uplift and erosion in the warm and humid conditions of the Palaeogene and Neogene led to the removal of huge amounts of rock. By the end of the Neogene, about 2.6 million years ago, climate had cooled dramatically. We were about to enter the Quaternary Period, which we are still in today, and whose glaciations have helped shape today’s landscape.
The landscape as we recognise it started to take shape long before the Quaternary. However, the area would have looked very different back then, with different drainage patterns on rocks now eroded away. The Lune Valley did not yet exist and streams flowed north off the Howgills towards the Eden Valley. At one time the northern Howgills were probably drained by a single river, which flowed north and carved Potts Valley. As the upper Lune Valley developed, drainage to Potts Valley was cut off. During the Quaternary, glacial meltwater poured through the valley, eroding it further. Today’s Potts Beck is a ‘misfit’ stream, flowing through a valley originally cut by a larger river and later enlarged by meltwater.