Jackson, Ian. Cumbria Rocks — 60 extraordinary rocky places that tell the story of the Cumbrian landscape. Newcastle upon Tyne : Northern Heritage, 2022.
The richly illustrated and accessible book series of Cumbria, Northumberland and Durham Rocks are available to purchase from Northern Heritage.
Theme: Earthquakes and folded rocks
25 Brothers Water bounding fault. You can park at Cow Bridge and walk south or look down on Brothers Water from Kirkstone Pass
Gaze north down Kirkstone Pass. The valley and its steep, ruler-straight sides are striking, especially the west shore of Brothers Water.
Why is this valley, and many others in the Lake District, so linear? The explanation is geological. Events many millions of years apart have produced the landscape we see today. Several episodes of Earth movements caused faulting which has broken these 450-million-year-old rocks into a jigsaw of fragmented pieces. The fault lines became zones of weakness and rivers that flowed long before the Ice Age, eroded their courses along them. In the last 2.6 million years successive glaciers followed those river valleys and carved deeper and broader ‘U’ shaped troughs. When the glaciers melted, they disgorged vast amounts of sediment which produced the flat valley bottoms; something that the rivers and streams continue to do today. Brothers Water and the valley’s straight lines are because of large faults on either side and because of the action of rivers and glaciers that followed them. In a final act debris flowing down Hayeswater Gill through Hartsop created a barrier of sand and gravel across the valley floor. The story of how this landscape evolved is based on many decades of geological research. But like all geological explanations, it is an interpretation of data available today: data about the shape of the land, about rock types, and our knowledge of how processes within the Earth and on its surface work. As we gather new data our understanding and explanations may change, that is the way science progresses.
The name Brothers Water has a tragic origin. It used to be called Broad Water, but two brothers were said to have drowned in the late 18th century when they fell through the lake’s frozen surface. They were possibly not the first brothers to do that. You could see goosander, cormorant, common sandpiper and coot on the lake and there is a typical northern meadow on the eastern shore with globeflower, wood crane’s-bill and great burnet.