THE BIRDS OF NORTH KENT. 43 



clearing the mud out of them at intervals, and heaping it up on 

 their banks. That is the history of many of the tortuous ditches 

 which wind their way between the meadows. Then, in order to 

 assist or complete the system of surface-water drainage, straight 

 ditches have been cut connecting the natural ones already exist- 

 ing. So that the waters of the marsh -land fall roughly into 

 three divisions. There are the wide fleets, once the main creeks 

 of the salt-marsh, now getting gradually narrower and shallower 

 with the encroachment of their own vegetable growth. Then 

 there are the narrow winding ditches, formerly the smaller run- 

 nels of the salting in which the silting process of nature has 

 been prevented by the intervention of man. And, finally, there 

 are the straight ditches, which are quite evidently, in their 

 entirety, the work of men's hands. Some of the land has been 

 enclosed within fairly recent years. It is called " new land " by 

 the residents, who nevertheless cannot recollect the actual 

 enclosure of it. But, according to the documentary evidence 

 of ordnance maps, there are evidently several large tracts which 

 have been enclosed between the survey upon which the present 

 maps are based and the survey upon which the older maps were 

 based. But both these surveys were spread over such a long time 

 that I have found it impossible to get exact dates. 



There is an interesting fact to note in connection with the 

 silting up of creeks. It appears that those creeks which are still 

 open to the tide, but in which there is no through scour, will shrink 

 more quickly in width than those which have now been shut 

 up from the sea for many years. The channel gets narrower 

 although it remains deep. On the other hand, the fleets inside 

 the wall get shallower, but remain their ancient width. The 

 evidence on which I base this statement is that in the year 1840 

 a winding portion of Dartford Creek was shut out of the tide-way 

 by the cutting of a new straight channel. But this winding 

 portion, although it missed the scouring of the direct current, 

 has never been entirely shut off from the tide. Presumably its 

 channel was as wide at the time of making the new cut as the 

 rest of the creek — say, some eighty to a hundred feet. At the 

 present day the winding portion of the old creek is scarcely 

 twelve feet wide. All the fleets in the marsh are much wider 

 than the creeks outside the wall, of which they were once a part. 



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