Box Hill Community
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The current of the river being much obstructed by the interposition of those hills, called Box-Hill ... it forces the waters as it were to find their way through as well as they can; and in order to do this, beginning, I say, where the river comes close to the foot of the precipice of Box-Hill, called the Stomacher, the waters sink insensibly away, and in some places are to be seen (and I have seen them) little channels which go out on the sides of the river, where the water in a stream not so big as would fill a pipe of a quarter of an inch diameter, trills away out of the river, and sinks insensibly into the ground. In this manner it goes away, lessening the stream for above a mile, near two, and these they call the Swallows.
Today we know more about swallow holes, which occur only in limestone rocks, of which chalk is a form. As Defoe explains, they are holes or cracks in the river bed or river banks through which river water passes into underground channels, so diminishing the flow of the river. The average flow of the Mole above Burford Bridge is 63 million gallons a day, while at Leatherhead, down-stream, it is 55 million gallons: eight million gallons have therefore disappeared some- where along the way, the major part of which must go down the swallows. This leakage from the river goes on all year round, but in the summer the surface stream occasionally disappears completely. The bed of the Mole is then dry, except for a few residual pools, from Ham Bank near Norbury Park to a point near Leatherhead, where water emerges again into the river bed from a series of springs.
There are many subsidence holes, some old and some more recent, at the foot of Box Hill and elsewhere in the valley. In 1940 a medium-sized oak tree dropped without warning into a chasm behind a house in Mickleham. Apart from such odd happenings, the river valley holds other secrets. The elusive kingfisher may be seen at the foot of The Whites where the river is fordable by means of stepping stones. The same area harbours grey and pied wagtails, as well as moorhen, mallard and the gaudy semi-wild mandarin duck. Wild mink have been reported and, even more bizarrely, a small colony of the rose-winged parakeet has become established near the river. Box Hill from Denbies Hill. The River Mole winds between the trees at the base of the escarpment The River'Mole is something of an enigma. According to one school of thought, its name derives from its habit of burrowing underground, like its animal namesake. Others argue that in the Middle Ages the Mole was known as the Ernlyn Stream and its present name stems from Molesey where the river joins the Thames.Daniel Defoe, who lived in the neighbourhood for a time in the early eighteenth century, recorded his detailed observations of the River Mole in A Tour through the Whole Island of Great Britain.