11 



NINTH WINTER MEFTING.— MARCH 7th. 1905. 



'*THE INTERMITTENT STREAMS OF EAST KENT."— By Mk. G. 



BUCKINGHAM. 



At the meeting held on March 7th, an interest- 

 ing paper on " Tbe Intermittent Streams of East 

 Kent "was read by Mr. C. Buckingham, of Canter- 

 bury, in the course of which he observed ; 



Perhaps the nailboume, or intermitteot stream, 

 most familiar to residents of Canterbury is tbe 

 stream which has its course through tbe Elham 

 Valley, and I think this stream will be most 

 generally remembered flowing through that por- 

 tion of the valley in the neighbourhood of Bridge, 

 Bekesbourne, and Patrixbourne, for these villagns 

 are so well known and perhaps many have already 

 given this stream the credit of adding much 

 charm to tbe district. I will imagine for the time 

 being that we are taking one of those well earned 

 half-holiday trips into toe country and leaving 

 the humdrum of city life for a time behind us 

 . . . Having passed the village of Bridge and 

 turned to the right into Bourne Park, probably 

 some have, as I have myself, walked down to the 

 edge of the lake and watched the wild ducks and 

 moorhens enjoying their freedom, or may have 

 crept down to tbe edge of the water to catch a 

 glimpse of tbe speckled trout lying in the stream. 

 Now I feel many may have enjoyed such an 

 excursion and may have looked forward to tbe 

 pleasure aguin, and, then choosing a suitable day, 

 have set out to visit the same old spots which have 

 impressed them in some earlier visit ; then what 

 a disappointment to And this interesting st.*eam 

 completely dry, such as has been my experience. 

 Instead of tbe familiar cries of the wild birds at 

 the lake's edge, I have been impressed at finding 

 it dry and all life which such a stream brings — 

 the luxuriant growth of plants by tbe water's 

 edge, the life in the water, and water birds — have 

 disappeared. It was on such an occasion as this, 

 when walking about 'U the dry bed of the lake 

 with a friend, amung tbe flora, which had already 

 changed from the aquatic to the terrestrial, that 

 my thoughts turned to this extraordinary river, 

 and naturally the eff-ct suggests to the mind, 

 What is the cause. Whv should a river appear 

 abruptly at intervals a'mist regularly, then run 

 for a certain period and as suddenly stop y 



In seeking infurmation of these nailbuurnes of 

 those who lived along tbe course, in all my 

 enquiries I found the most intelligent idea was 

 that the flow was caused by water accumulating 

 in a cavity under the hilts, and many seemed to 

 think that, after taking several years to fill, this 

 cavity rapidly emptied itself by syphon acti"n 

 and flowed along tbe course to the sea. I locked 

 up the works of several geologists, and found them 

 very hazy indeed on the subject. I found sevnral 

 wiiters, too, supposed tb^-se intermittent streams 

 in the chalk to b-^ caused by the existence of a 

 reservoir, with but one outlet, which, by some 

 .accident in tbe stratification, curves upwards a 

 few yards before turning down again. They 



thought water would percolate through the chalk 

 into the reservoir, and, when full, empty itself by 

 syphon action. Some writers give us the idea 

 that they are caused by the dip of the strata, the 

 dip being north, with the impervious gault below 

 which crops up at the foot of the Noith Downs. 

 It is fiupposed that the nailbouroe? issue from the 

 chalk escarpment when saturation level is above 

 the impervious line. This may account for a few 

 intermittent springs in other valleys, but only 

 indirectly can it influence the nailbournes ; 

 besides there are several springs issuint; from the 

 escarpment which feed the Stx)ur and East Stour, 

 which are practically permanent. 



Obviously the way to account for the strange 

 doings of these intermittent streams was to study 

 the nature of the strata of the district and to 

 watch their behaviour during one of their flowing 

 periods. The wet season of 1903 gave me the 

 opportunity of seeing for myself the way these 

 streams rose, flowing along the old courses, the 

 occupying of roads, the flooding of fields, and 

 finally getting more and more feeble till they 

 ceased, and again became dry courses. 



After giving a considerable portion of my leisure 

 for eighteen months, with the aid of cycle and 

 camera, and the willing help and company of 

 several friends, I came to tbe conclusion that the 

 nailbournes of our district are caused simply by 

 the gradual rise and fall in tbe line of saturation 

 bt'oeath the chalk hills. While the bottoms of the 

 valleys (which may be regarded as flood courses of 

 subterranean streams) are above the line of 

 saturation, in ordinary seasons, the water, after 

 P'-rcul tting through tbe hills, makes its way under- 

 ground through the chalk, there generally being 

 a usual spring head in a lower part of the valley 

 on the usual line of saturation, but, after L-ng con- 

 tinued rains, the level of satnra'ion rises and 

 warer isT^ues to the surface at some higher point 

 oi generally several higher points up the valley. 



It will be as well here to consider the underlying 

 strata of our district, and to do this it will be as 

 well to climb one of the hills, say St. Thomas' Hill, 

 and occupy a spot which will give n^ a good view 

 ot the valley which the Stour has cut. We may 

 perhaps see, on the sides of the distant bills, 

 places where the surface soil has been removed, 

 and we at once notice chalk. The entire stratum 

 of which our bills and valleys are cut is chalk 

 (there is in some cases a tertiary deposit on the 

 top of the hills, particularly north of Canterbury, 

 but this does not affect the nailbournes^). While 

 standing on the top of this bill, we may perhaps 

 nt)tice that behind us the surface is fairK flur.; we are 

 standing on a plateau, and in jfurnnytng m any 

 direcion we go down into valleys aud up again on 

 to the plateau These valleys, according to their 

 depth and the nature of the alluvial deposit in the 

 valley bottomSj are sometimes dry, sometimes with 



