Draiiiaye of PVhittlesea Mere. 
151 
comprcssod to admit ol a second diessinj^ of clay being raised 
directly from beneath.* 
It is to a tract of fen situated beyond the reach of the former 
Hoods, and, therefore, more remote from the Mere than the lands 
last mentioned, that the clay is now being applied by railway. 
Antecedent to this work, some attempts at cultivation seem to 
have been made ; but the task must have been most unsatisfac- 
tory to a man of enterprise, when he saw his utmost efforts 
repeatedly met by the very inadequate return which the unclayed 
peat would make even in a favourable season. Such efforts, 
however, have not been thrown away, as, under any circum- 
stances, a good deal must be done to the rough surface of the fen, 
full of inecjualitics to the extent of from 1 to 2 feet, and covered 
with a felt of sedgy grasses and roots, before the surface is level 
enough to receive the clay, or the mass of roots is broken up into 
anything which deserves the name of soil for admixture with it. 
* The following grounds may be assigned for the belief that the clay will ulti- 
mately be raised directly from below the fen. 
Around the Mere, when the water was drawn off, there was a bed of peat as much 
as 22 feet in thickness above the blue clay. As Mr. Wells has shown, this surface 
has subsided at the rate of about 9 inches in a year, or G feet in all since that 
date ; or in other words, this bed of peat has been already compressed to that extent. 
The surface over the bed of the Mere has in the same period sunk 3 feet 
6 inches. This subsidence does not admit of so easy an explanation, for on the 
site of the Mere there are now only about 5 feet of soil above the blue clay, of 
which the 3 upper feet consist of silt combined with some peat (as shown in 
Analysis No. 3), and the 2 lower feet of compressed peat. 
It may seem a startling assertion that this subsidence on the Mere bed must be 
attributed chiefly to the underlying peat having been compressed from a thickness 
of over 5 feet to that of 2 feet ; but any other explanation of the phenomena would 
probably be attended with even greater difficulties than this. At the period when 
the formation of the peat began (probably in consequence of some sudden elevation 
•of the district), the surface of the area over which it extended must, from the 
nature of the case, have been nearly level, — just below or just above the range 
of the water-level. When water began to stand in pools, the nucleus of the Mere 
would be formed in a depressed rather than an elevated portion of this area. 
It can then hardly be supposed that the clay surface under the Mere is, or ever was, 
higher than in the surrounding fen. And yet at this spot it is now within .5 feet of 
the surface, although elsewhere it is sunk below 1 6 feet of peat. It would be interest- 
ing to know how much the top of the 22 feet post driven through the peat (which 
now stands 6 feet out of ground) is above the present level of the Mere bed. But 
apart from this and other such inquiries, we may state our case briefly as follows : — 
If the surface of the blue clay be level and incompressible : 
If the silt would not shrink greatly when dried (say more than 6 inches in the 
51 feet) : 
. Of the subsidence of the Mere bed (amounting in all to 3 feet 6 inches), 3 feet 
must be due to the reduction of the peat from a thickness of 5 feet to 2 feet; 
and thus we should obtain a maximum estimate of the amount of compressibility 
of peat in 9 years, when it has previously been thoroughly saturated with water, 
and subsequently exposed to the full influence of a powerful draining apparatus. 
The thickness of 22 feet of peat seems to be a maximum thickness over a consider- 
able area : at the rate above indicated, these 22 feet would be reduced to 9 feet in 
nine years as the maximum depth of the clay if the soil were thoroughly exposed 
to drying influences as the Mere bed has been; whilst on other spots the clay 
would be proportionately nearer to the surface. 
