THE FAUNA AND FLORA OF FLORDON COMMON. 175 
absence of introduced sand or clay, but is compatible with 
the theory that this white earth was formed in a pool occupied 
by Chara, the fruits being very abundant, and the debris 
of which would contribute much lime and little silica, the ash 
yielding 54’8 and 0'3 per cent, respectively (Kerner). The 
brown deposits D and E, with a larger proportion of ash, 
may have been built up by a sedge type of vegetation, whose 
stems yield an ash containing 50 to 70 per cent, of silica. 
In both cases the bulk of lime is not contributed by the 
decaying vegetable matter, but is precipitated from the 
calcareous water by aquatic vegetation, a process that is 
always in operation in sunlight. Some portion of the ash 
is of non-organic origin, but microscopic examination shows 
that a considerable portion of insoluble matter consists of 
plant skeletons. The high ash value of E is due to grit, 
which visibly contributes to the 310 millegrams by weight 
obtained, a fragment of brick-like substance and 10 quartz 
grains picked out with forceps weighing 20 millegrams. 
Of changes on the common we have very little evidence. 
Mrs. Potter has lived all her life at the cottage adjoining the 
common on the north, and her father came to live there in 
1813, so that the family traditions cover almost a century. 
She says that the common is very much drier now than 
when she was a girl. Much of the marshy portion was then 
impassable, and in many places a rake could be put into the 
water without the bottom being touched. The low portion 
of the common was formerly intersected with drains, now 
grown up, though distinguishable at certain seasons of the 
year. Of changes (if any) in the flora we have no record. 
On August 17th, 1885, Mr. H. D. Geldart and Mr. H. G. 
Glasspoole visited the common, and all the twenty plants 
they noted* were (with the exception of Sftarganium neglectum ) 
found there by us in 1909. f 
Economically the common appears to be of no great 
value. Horses, cattle, geese, hens, ducks and turkeys feed 
* Trans. Norfolk and Norwich Nat. Soc. vol. iv. p. 258. 
t In the " Diatomacese of Norfolk ” (Ibid. ii. 336, iii. 754), Mr. F. G. 
Kitton records many from Flordon. 
VOI.. ix. 
N 
