41 6 Salisbury . — The Soils of Blakeney Point: A Study of Soil 
averages show a perfect gradation from XX to VIII, with a subsequent 
decrease in acidity (rise of p. H.) in the oldest laterals. 
It is evident that the inundation of these latter, infrequent though it be, is 
sufficient to restrain the development of a high acidity, and hence by favour- 
ing the oxidation of the organic material precludes the accumulation of 
a high proportion of humus. 
The crest of the lateral banks, therefore, presents us with a definite 
edaphic sequence of the same general type as that shown by sand dunes or 
by woodlands, but whereas in these cases the increasing acidity would appear 
to be more or less continuous till the curve flattens out, here a topo- 
graphical change intervenes to cause retrogression. 
Vegetation {cf. Appendix , Table XIV). 
The high elbows of VII and VIII exhibiting as they do the maxi- 
mum of both height and age, we not unnaturally find here the greatest 
departure from the maritime condition. The less specialized habitat, con- 
sequent upon the increased proportions of organic material and finer soil 
particles, and the still greater freedom from tidal inundation, associated as 
these are with increased stability and the operation of the time factor, 
brings with it an augmented flora. It is interesting in this connexion 
to note that, as shown in the accompanying lists (Appendix, Table XIV) 
for laterals of varying age, the maximum number of species, viz. fifty-one, 
is recorded for Bank VIII, whilst the smallest number, viz. six, is present 
on the newly-formed lateral. That the time factor alone is not responsible 
is shown, however, by the diminution in number on the oldest laterals 
as shown below. 
Number of Species present on Crest of Laterals of Increasing Age. 
Y oungest < > Oldest 
XX. XVII. XII. VIII. VII. VI. IV. III. I. 
No. of species 6 6 34 51 36 25 21 24 16 
On the youngest phases several species are present whose occurrence 
may be attributed to their proximity to dunes. This especially applies to 
Bank XII, where alone we find Phleum arenarium and Stellaria boreana 
occupying a shingle crest. Other species which are characteristic of the 
earlier phases and absent from the oldest are Senecio jacobaea, Rumex 
crispus v. trigranulatus , Glaucium luteum , and Arenaria peploides. 
Silene maritima , although common on the oldest banks, is yet not so 
abundant as on those of medium age, nor are the individuals so vigorous. 
Amongst the species confined to the c high elbow J are Galium verum , 
Trifolium procumbens , and Vicia angusti folia. These, together with Air a 
praecox ) Festuca ovina, Plantago Coronopus , Trifolium arvense , T. striatum , 
