ALLUVIUM. 7 1 



Wandle below Hackbridge, south of Mitcham. Alluvial meadows 

 border the Thames between Kew and Richmond, notably in 

 front of Syon House. 



There is a spread of Alluvium between Barnes and Hammer- 

 smith Bridge, a tract into which the Beverley Brook runs ; and 

 there is Alluvium at Westminster, Pimlico, in parts of Lambeth, 

 Southwark and Bermondsey, at Rotherhithe and the Isle of 

 Dogs, now a region of docks. Thence north of the Thames are 

 the extensive marshes of Plaistow, with Canning Town and 

 Beckton, and numerous docks, the Barking Level, and the 

 Rainham, Aveley and West Thurrock Marshes. 



Along the Lea Valley there are broad tracts of marsh land 

 from Enfield to Hackney and Blackwall ; and along the Roding 

 Valley there is a continuous strip of Alluvium. 



On the south side are the marshes of Greenwich, Plumstead, 

 Erith and Dartford; the Cray and the Darent unite below 

 Crayford and Dartford, and the last-named town is largely built 

 on the Alluvium. 



With regard to the levels of the Alluvium, we find along the 

 Colne valley from near Watford to the Moor above Staines, a 

 distance of about 20 miles, that there is a fall from 180 to 50 ft., 

 or more than 6 ft. per mile. In the valleys of the Lea and Roding, 

 the fall, within the district, is respectively 3 and 7 ft. per mile. 

 In the Darent Valley from Shoreham Castle to the mouth of thb 

 river, a distance of about 10 miles, there is a fall from 167 to 5 ft., 

 or about 16 ft. per mile. In these cases the fall is not uniform. 

 Along the main river from above Staines to Walton-upon-Thames 

 the descent is from 50 to 30 ft. above O.D. in about 7 miles, or 

 3 ft. per mile. At Barnes, 11 miles further (in a direct line), the 

 Alluvium is about 14 ft. above O.D. ; while from Rotherhithe 

 to the eastern part of our district near West Thurrock, much of 

 the Alluvium is but 4 or 5 ft. above O.D. 



Prior to the embanking of the Thames there was much 

 swampy ground at Chiswick, Chelsea and Fulham, also in the 

 lower grounds at Wandsworth, Battersea, Lambeth, Southwark, 

 Bermondsey, Rotherhithe, Deptford and Greenwich. 



Small islands of a gravelly or muddy nature, known as aits 

 or eyots, 1 occur along the Thames at various spots between 

 Egham and Staines, between Shepperton and Wey bridge, at 

 Sunbury, between West Molesey and Hampton Court, at 

 Surbiton (Raven's ait), Teddington, Petersham, Twickenham 

 (Eel Pie Island), Isleworth, Brentford (Corporation Island), and 

 Chiswick. Formerly there were islets at Putney, Chelsea (Chesil 

 or Shingle Island), 2 Battersea (St. Peter's Island), Westminster 

 (Isle of Thorns or Thorney, where the Abbey now stands), and 

 Bermondsey. Chertsey is situated on an island of gravel in the 

 Alluvium. The Isle of Dogs was a more or less isolated bank 

 of mud, subject in old times to inundation at high tide. Frog 



1 Indicated by the Anglo-Saxon suffix ey or ea in the names of places. 



2 Chelsea may be derived from cealc hythe == chalk quay. 



