39 2 Salisbury . — The Soils of Blakeney Point : A Study of Soil 
The writer gladly takes this opportunity of expressing his indebtedness 
to Professor F. W. Oliver for having asked him to undertake a soil survey 
of this area. Thanks are also due to Dr. P. Haas for the preparation of 
standard buffer solutions, to Dr. Brady for electro metrical checks, to 
Lieut. G. N. Oliver for the preparation of Text-fig. I, and to the following 
for assistance in the collection of soil samples and in the hydrogen-ion 
determinations : Miss V. Anderson, Miss S. Hurwitz, Miss E. Tyler, and 
Mr. L. Cole. 
Except where otherwise stated the samples were taken to a uniform 
depth of 4 in., and io grm. of the undried soil were stirred up with 50 c.c. 
of water neutral to brown-thymol blue. In practice it was found that 
equilibrium was attained in half an hour, after which the extract was 
filtered and, after discarding the first filtrate, the hydrogen-ion concentration 
was determined colorimetrically by the aid of standardized buffer solutions 
and the usual indicators. 
No detectable difference in the results was obtained by using twice 
as much soil, by lengthening the period of extraction, or by adding the 
indicator to centrifugalized samples. One may therefore assume that the 
varying water-content of the samples did not introduce any error into 
the results, nor are these vitiated by filtration. 
The carbonate content was determined by means of a Collins 
calcimeter, applying the usual corrections, and the results are expressed 
as calcium carbonate in 100 grm. of soil dried at ioo° C. 
The general topography of the area and its vegetation have already 
been dealt with elsewhere (cf. Oliver and Salisbury, Trans. Norfolk and 
Norwich Nat. Soc., vol. ix, 1913), but for convenience we shall here summarize 
the chief features, at the same time 'indicating the distribution of the soil 
•samples taken. 
The salient features of the area are shown on the map (Text-fig. 1), 
where the sequence of numbers and letters shows the dunes and lateral 
shingle beaches of successive age. 
A. The Dune System. 
The earliest phase in dune development at Blakeney Point is usually 
marked by the collection of sand around a young plant of Psamma 
arenaria . As the dune thus initiated accretes sand the marram grass 
becomes covered and is thereby stimulated to renewed growth — in this way 
constituting a skeletal system which enlarges pari passu with the growing 
sand-hills and permeates the entire structure of the adult dune. 
Of this skeletal system the ultimate ramifications bear the green leaves 
at the surface, whilst the older parts, formed when the dune was young, 
exhibit progressive decay till in the actual heart of a large dune only 
disintegrated fragments may remain. 
