VEGETATION OF STILL WATER 



it potato or corn, now has the weeds 

 that belong to cultivated areas, The 

 introduction of roads, usually mended 

 with chalk, accounts for another set of 

 plants not natural to the Fen region. 

 Apart from the plants due to the in- 

 fluence of man, the Fen district offers a 

 great variety of vegetation, for it is 

 possible to trace at least three distinct 

 deposits in this region. There is the 

 gravel brought down by the rivers ; the 

 peat formed by the flooding of the dis- 

 trict and accumulation of vegetable 

 matter, now reaching a thickness of 

 twenty feet in parts ; the silt deposited 

 by the sea, as it burst in behind the 

 Alluvium, is laid down in considerable 

 quantity over the level ground on which 

 a river spreads when in flood, for the 

 water in spreading out on the plain 

 loses velocity and consequently power 

 of transport, and the mud, soil, etc., 

 held in suspension falls on the plain. 

 This must have happened over and 

 over again in the Fen country, and 

 accounts for the presence of gravel and 

 peat in this region ; the villages usually 

 stand on gravel beds, which are no- 

 where higher than 56 feet, and slope 

 down in some parts under the peat and 

 silt. The peat has ceased to grow, pro- 

 bably because the climate is getting 

 drier ; it occupies a larger area of fen- 

 land than the gravel, and is charac- 

 terised by an almost even surface and 

 the absence of hedges. Ditches lined 

 with the Common Reed a true Grass 

 Phragmites communis, take their 



FIG. 13. Common Reed 

 (Phragmites communis}. 



