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SK6145 : Waterfall on the Lambley Dumble SK6145 : Top Dumble waterfall (1) SK6145 : Top Dumble waterfall (2) SK6145 : Top Dumble waterfall (3) SK6145 : Top Dumble waterfall (4)
This waterfall has a fall of around 1.5 metres, but is a textbook example of a cill waterfall with a sharply defined tail gorge.
The rock strata, basically a softish mudstone also seen to advantage here
SK6145 : Top Dumble stream (1),
have been laid down in thin layers, almost horizontal at this point. The harder layers wear more slowly and provide a cill over which the water falls. Softer layers underneath erode from water and frost action to a point at which the cill is undercut and eventually breaks away. The result is a narrow gorge of fairly consistent width forming the tail of the waterfall.
This form of erosion explains how the dumbles have formed locally as narrow steep-sided ravines at the bottom of otherwise rounded-bottom valleys. Even the cill of the waterfall here is some 4-5 metres below the surrounding field level, giving a depth at the foot of the fall of around 6 metres.