On the morning of 25th September the rain gauge in my front garden contained 54mm. of rain; the following morning I recorded a further 25mm. This meant that in 48 hours more than three inches of rainfall had hit my already well-mossed lawn – roughly the same volume as in the whole month of September last year. I went down to the Old Bridge to look at the river. The debris and crushed vegetation indicated that it had already fallen several inches but the roaring spate was still impressive – huge volumes of brown peaty water tearing under the bridge, patterns of creamy-foamed waves indicating the way the piers distorted the flow. It made me reflect on the power of water to scour and sculpt not only the riverbed but the whole landscape in which I was standing.
Indeed, Wharfedale was formed by water. Imagine a shallow ancient sea depositing the remains of sub-marine creatures, followed by a huge river delta that left behind coarse sands and muds, and all this becoming compressed into the limestones and gritstones underlying our valley today. It was later gouged and sculpted by ice, then engraved by rushing streams into our familiar landscape. We have easy access to two very different kinds of scenery: the lower dale with its gritstone ridges, crags and acid heather-moorland, the upper dale with its glorious limestone scenery. Since limestone dissolves in the slightly acid water of running streams we have not only the rare habitat of limestone pavement, its grykes sheltering communities of special plants, but also a whole dangerous and magical world below ground – a world of potholes, caverns, underground rivers and lakes.
Staring down into the turbid flood waters, I can see how the sandbanks and shingle upstream have been rearranged yet again by the power of the water. How can anything survive in such an unstable environment? Truth is that instability is one of its defining features and creatures have evolved to thrive here. Some may take evasive action: a party of mallards have quitted the rollercoaster river and potter happily on a temporary pool in the adjacent meadow, dippers and kingfishers have no doubt withdrawn up side-streams to forage, and the creatures of the riverbed grimly hang on. Boulders may be shifted, trees undermined and plants redistributed – but it’s all part of the life of a Dales river.