A single blog off our current theme – Dewponds.
On the recent walk in the south-west Yorkshire Wolds came across this man-made dewpond (see above and yesterday’s photo), although now much overgrown.
The purpose of a dewpond was to provide a water supply for grazing animals by harnessing natural processes. This dewpond was formed by excavating a shallow depression at the bottom of the dry valley and then lining it with smoothed cement and a more sturdy rim. At dawn the cool night air would linger in the valley bottom and condense on the cold cement surface, any rainfall, day or night, would add to the supply. The surviving hawthorns around part of the rim may not be coincidental as shading from the midday sun would reduce loss by evaporation. Currently the open grassy Swin Dale is not grazed but surely sheep, and maybe cattle, would have grazed here in the past.
I have a copy of an article written about the year 2000 from the Journal of Landscape History (although I was not then a member) entitled ‘From dolines to dewponds: a study of water supplies on the Yorkshire Wolds’. Incidentally a doline was a depression in the surface above porous rock formed not so much by the collapse of underground caves as by the dissolving of parts of the solid bedrock. Man-made dewponds, like dolines, could be lined with puddled clay to form the impervious lining.
Other water-supplying features covered by the article included natural ponds in dry valley locations, these resulting from the bottom of the dry valley being at the level of the water table in the porous bedrock. Of course, the article also dealt with hand-pumps where the bore had been dug into the bedrock, and wells. Apparently the average well-depth in the Yorkshire Wolds was about 60 feet. I always find it astonishing that wells were dug to such a depth with hand-tools.
(next time back to disused rail-lines).